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By NASA
The study of X-ray emission from astronomical objects reveals secrets about the Universe at the largest and smallest spatial scales. Celestial X-rays are produced by black holes consuming nearby stars, emitted by the million-degree gas that traces the structure between galaxies, and can be used to predict whether stars may be able to host planets hospitable to life. X-ray observations have shown that most of the visible matter in the universe exists as hot gas between galaxies and have conclusively demonstrated that the presence of “dark matter” is needed to explain galaxy cluster dynamics, that dark matter dominates the mass of galaxy clusters, and that it governs the expansion of the cosmos.
X-ray observations also enable us to probe mysteries of the Universe on the smallest scales. X-ray observations of compact objects such as white dwarfs, neutron stars, and black holes allow us to use the Universe as a physics laboratory to study conditions that are orders of magnitude more extreme in terms of density, pressure, temperature, and magnetic field strength than anything that can be produced on Earth. In this astrophysical laboratory, researchers expect to reveal new physics at the subatomic scale by conducting investigations such as probing the neutron star equation of state and testing quantum electrodynamics with observations of neutron star atmospheres. At NASA’s Marshall Space Flight Center, a team of scientists and engineers is building, testing, and flying innovative optics that bring the Universe’s X-ray mysteries into sharper focus.
A composite X-ray/Optical/Infrared image of the Crab Pulsar. The X-ray image from the Chandra X-ray Observatory (blue and white), reveals exquisite details in the central ring structures and gas flowing out of the polar jets. Optical light from the Hubble Space Telescope (purple) shows foreground and background stars as pinpoints of light. Infrared light from the Spitzer Space Telescope (pink) traces cooler gas in the nebula. Finally, magnetic field direction derived from X-ray polarization observed by the Imaging X-ray Polarimetry Explorer is shown as orange lines. Magnetic field lines: NASA/Bucciantini et al; X-ray: NASA/CXC/SAO; Optical: NASA/STScI; Infrared: NASA-JPL-Caltech Unlike optical telescopes that create images by reflecting or refracting light at near-90-degree angles (normal incidence), focusing X-ray optics must be designed to reflect light at very small angles (grazing incidence). At normal incidence, X-rays are either absorbed by the surface of a mirror or penetrate it entirely. However, at grazing angles of incidence, X-rays reflect very efficiently due to an effect called total external reflection. In grazing incidence, X-rays reflect off the surface of a mirror like rocks skipping on the surface of a pond.
A classic design for astronomical grazing incidence optics is the Wolter-I prescription, which consists of two reflecting surfaces, a parabola and hyperbola (see figure below). This optical prescription is revolved around the optical axis to produce a full-shell mirror (i.e., the mirror spans the full circumference) that resembles a gently tapered cone. To increase the light collecting area, multiple mirror shells with incrementally larger diameters and a common focus are fabricated and nested concentrically to comprise a mirror module assembly (MMA).
Focusing optics are critical to studying the X-ray universe because, in contrast to other optical systems like collimators or coded masks, they produce high signal-to-noise images with low background noise. Two key metrics that characterize the performance of X-ray optics are angular resolution, which is the ability of an optical system to discriminate between closely spaced objects, and effective area, which is the light collecting area of the telescope, typically quoted in units of cm2. Angular resolution is typically measured as the half-power diameter (HPD) of a focused spot in units of arcseconds. The HPD encircles half of the incident photons in a focused spot and measures the sharpness of the final image; a smaller number is better.
Schematic of a full-shell Wolter-I X-ray optic mirror module assembly with five concentrically nested mirror shells. Parallel rays of light enter from the left, reflect twice off the reflective inside surface of the shell (first off the parabolic segment and then off the hyperbolic segment), and converge at the focal plane. NASA MSFC NASA Marshall Space Flight Center (MSFC) has been building and flying lightweight, full-shell, focusing X-ray optics for over three decades, always meeting or exceeding angular resolution and effective area requirements. MSFC utilizes an electroformed nickel replication (ENR) technique to make these thin full-shell X-ray optics from nickel alloy.
X-ray optics development at MSFC began in the early 1990s with the fabrication of optics to support NASA’s Advanced X-ray Astrophysics Facility (AXAF-S) and then continued via the Constellation-X technology development programs. In 2001, MSFC launched a balloon payload that included two modules each with three mirrors, which produced the first focused hard X-ray (>10 keV) images of an astrophysical source by imaging Cygnus X-1, GRS 1915, and the Crab Nebula. This initial effort resulted in several follow-up missions over the next 12 years, and became known as the High Energy Replicated Optics (HERO) balloon program.
In 2012, the first of four sounding rocket flights of the Focusing Optics X-ray Solar Imager (FOXSI) flew with MSFC optics onboard, producing the first focused images of the Sun at energies greater than 5 keV. In 2019 the Astronomical Roentgen Telescope X-ray Concentrator (ART-XC) instrument on the Spectr-Roentgen-Gamma Mission launched with seven MSFC-fabricated X-ray MMAs, each containing 28 mirror shells. ART-XC is currently mapping the sky in the 4-30 keV hard X-ray energy range, studying exotic objects like neutron stars in our own galaxy as well as active galactic nuclei, which are spread across the visible universe. In 2021, the Imaging X-ray Polarimetry Explorer (IXPE), flew and is now performing extraordinary science with an MSFC-led team using three, 24-shell MMAs that were fabricated and calibrated in-house.
Most recently, in 2024, the fourth FOXSI sounding rocket campaign launched with a high-resolution MSFC MMA. The optics achieved 9.5 arcsecond HPD angular resolution during pre-flight test with an expected 7 arcsecond HPD in gravity-free flight, making this the highest angular resolution flight observation made with a nickel-replicated X-ray optic. Currently MSFC is fabricating an MMA for the Rocket Experiment Demonstration of a Soft X-ray (REDSoX) polarimeter, a sounding rocket mission that will fly a novel soft X-ray polarimeter instrument to observe active galactic nuclei. The REDSoX MMA optic will be 444 mm in diameter, which will make it the largest MMA ever produced by MSFC and the second largest replicated nickel X-ray optic in the world.
Scientists Wayne Baumgartner (left, crouched) and Nick Thomas (left, standing) calibrate an IXPE MMA in the MSFC 100 m Beamline. Scientist Stephen Bongiorno (right) applies epoxy to an IXPE shell during MMA assembly. NASA MSFC The ultimate performance of an X-ray optic is determined by errors in the shape, position, and roughness of the optical surface. To push the performance of X-ray optics toward even higher angular resolution and achieve more ambitious science goals, MSFC is currently engaged in a fundamental research and development effort to improve all aspects of full-shell optics fabrication.
Given that these optics are made with the Electroformed Nickel Replication technique, the fabrication process begins with creation of a replication master, called the mandrel, which is a negative of the desired optical surface. First, the mandrel is figured and polished to specification, then a thin layer of nickel alloy is electroformed onto the mandrel surface. Next, the nickel alloy layer is removed to produce a replicated optical shell, and finally the thin shell is attached to a stiff holding structure for use.
Each step in this process imparts some degree of error into the final replicated shell. Research and development efforts at MSFC are currently concentrating on reducing distortion induced during the electroforming metal deposition and release steps. Electroforming-induced distortion is caused by material stress built into the electroformed material as it deposits onto the mandrel. Decreasing release-induced distortion is a matter of reducing adhesion strength between the shell and mandrel, increasing strength of the shell material to prevent yielding, and reducing point defects in the release layer.
Additionally, verifying the performance of these advanced optics requires world-class test facilities. The basic premise of testing an optic designed for X-ray astrophysics is to place a small, bright X-ray source far away from the optic. If the angular size of the source, as viewed from the optic, is smaller than the angular resolution of the optic, the source is effectively simulating X-ray starlight. Due to the absorption of X-rays by air, the entire test facility light path must be placed inside a vacuum chamber.
At MSFC, a group of scientists and engineers operate the Marshall 100-meter X-ray beamline, a world-class end-to-end test facility for flight and laboratory X-ray optics, instruments, and telescopes. As per the name, it consists of a 100-meter-long vacuum tube with an 8-meter-long, 3-meter-diameter instrument chamber and a variety of X-ray sources ranging from 0.25 – 114 keV. Across the street sits the X-Ray and Cryogenic Facility (XRCF), a 527-meter-long beamline with an 18-meter-long, 6-meter-diameter instrument chamber. These facilities are available for the scientific community to use and highlight the comprehensive optics development and test capability that Marshall is known for.
Within the X-ray astrophysics community there exist a variety of angular resolution and effective area needs for focusing optics. Given its storied history in X-ray optics, MSFC is uniquely poised to fulfill requirements for large or small, medium- or high-angular-resolution X-ray optics. To help guide technology development, the astrophysics community convenes once per decade to produce a decadal survey. The need for high-angular-resolution and high-throughput X-ray optics is strongly endorsed by the National Academies of Sciences, Engineering, and Medicine report, Pathways to Discovery in Astronomy and Astrophysics for the 2020s.In pursuit of this goal, MSFC is continuing to advance the state of the art in full-shell optics. This work will enable the extraordinary mysteries of the X-ray universe to be revealed.
Project Leads
Dr. Jessica Gaskin and Dr. Stephen Bongiorno, NASA Marshall Space Flight Center (MSFC)
Sponsoring Organizations
The NASA Astrophysics Division supports this work primarily through the Internal Scientist Funding Model Direct Work Package and competed solicitations. This work is also supported by the Heliophysics Division through competed solicitations, as well as by directed work from other government entities.
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Last Updated Oct 15, 2024 Related Terms
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By NASA
29 Min Read The Next Full Moon is a Supermoon, and the Hunter’s Moon
A supermoon rises behind the U.S. Capitol, on March 9, 2020, in Washington. Credits:
NASA/Joel Kowsky The Next Full Moon is a Supermoon; the Hunter’s Moon; the Travel Moon, the Dying Grass Moon, or the Sanguine or Blood Moon; the start of Sukkoth; Sharad Purnima, Kumara Purnima, Kojagari Purnima, Navanna Purnima Kojagrat Purnima, or Kaumudi Purnima; the end of Vassa and Pavarana; the Thadingyut Festival Moon; the end of the Phaung Daw U Pagoda Festival; and Vap Poya.
The next full Moon will be Thursday morning, Oct. 17, 2024, at 7:26 a.m. EDT. This will be late Wednesday night for the International Date Line West time zone and early Friday morning from New Zealand Time eastwards to the International Date Line. The Moon will appear full for about three days around this time, from Tuesday evening through Friday morning.
This will be the third of four consecutive supermoons (and the brightest by a tiny margin).
As the full Moon after the Harvest Moon, this will be the Hunter’s Moon. The earliest written use of the term “Hunter’s Moon” identified in the Oxford English Dictionary is from 1710. According to the Farmer’s Almanac, with the leaves falling and the deer fattened, it is time to hunt. Since the harvesters have reaped the fields, hunters can easily see the animals that have come out to glean (and the foxes that have come out to prey upon them).
The Maine Farmer’s Almanac first published Native American names for the full Moons in the 1930s. Over time these names have become widely known and used.
According to this almanac, as the full Moon in October the Algonquin tribes in what is now the northeastern United States called this the Travel Moon, the Dying Grass Moon, or the Sanguine or Blood Moon. Some sources indicate that the Dying Grass, Sanguine, and Blood Moon names are related to the turning of the leaves and dying back of plants with the start of fall. Others indicate that the names Sanguine and Blood Moon are associated with hunting to prepare for winter. I have read that the name “Travel Moon” comes from observing the migration of birds and other animals preparing for the winter. I don’t know, but this name may also refer to the season when the more northern tribes would move down from the mountains for the winter. For example, both the Iroquois and Algonquin would hunt in the Adirondack Mountains during the summertime but leave in fall to avoid the harsh mountain winters.
As the full Moon in the Hebrew month of Tishrei, this full Moon falls near the start of Sukkoth, a 7-day holiday starting on the 15th day of the month. Sukkoth is also known as the Feast of Tabernacles or the Feast of the Ingathering. Sukkoth honors both the sheltering of the People of Israel during the 40 years in the wilderness in the Book of Leviticus as well as an ancient harvest festival in the Book of Exodus. Sukkot is named for the sukkah (booths or huts) traditionally built for the occasion that represent the temporary huts in which Israelites lived after escaping from Egypt. Families symbolically invite ancestors to share meals in the sukkah and spend as much time as possible there throughout the week. This year Sukkoth starts at sunset on October 16 and ends at sunset on October 23. See https://en.wikipedia.org/wiki/Sukkot for more information.
For Hindus, this is Sharad Purnima, also known as Kumara Purnima, Kojagari Purnima, Navanna Purnima Kojagrat Purnima, or Kaumudi Purnima. This is a harvest festival celebrated in a variety of ways. See https://en.wikipedia.org/wiki/Sharad_Purnima for more information.
For Buddhists, this Moon marks the end of Vassa, the three-month period of fasting for monks tied to the monsoons (Vassa is sometimes given the English names “Rains Retreat” or “Buddhist Lent”). There are numerous festivals and holy days associated with this Moon at the end of Vassa. Many Buddhists observe the holy day Pavarana on this day.
In Myanmar, this full Moon corresponds with the three-day Thadingyut Festival of Lights, also known as the Lighting Festival of Myanmar.
Also in Myanmar, this full Moon is near the end of the Phaung Daw U Pagoda Festival. This festival began on the first Waxing Moon day of the month of Thadingyut and will end a few days past this full Moon.
In Sri Lanka, this is Vap Poya, which is followed (usually within the lunar month) by the Kathina festival, during which people give gifts to the monks, particularly new robes (so this lunar month is sometimes called the Month of Robes).
In many traditional Moon-based calendars the full Moons fall on or near the middle of each month. This full Moon is near the middle of the ninth month of the Chinese year of the Dragon and Rabi’ al-Thani, also called Rabiʽ al-Akhir, the fourth month of the Islamic year.
As usual, the wearing of suitably celebratory celestial attire is encouraged in honor of the full Moon. Enjoy this harvest season, remember your ancestors, and consider camping out with your family. Here’s wishing you safe travels!
Summary of Key Celestial Events
Here are more celestial events between now and the full Moon after next (with specific times and angles based on the location of NASA Headquarters in Washington, D.C.):
As Autumn continues the daily periods of sunlight continue shortening. On Thursday, Oct. 17, (the day of the full Moon), morning twilight will begin at 6:22 a.m. EDT, sunrise will be at 7:20 a.m., solar noon will be at 12:53 p.m. when the Sun will reach its maximum altitude of 41.5 degrees, sunset will be at 6:26 p.m., and evening twilight will end at 7:24 p.m.. By Friday, Nov. 15, (the day of the full Moon after next), we will have switched from Daylight Saving to Standard Time. Morning twilight will begin at 5:51 a.m. EST, sunrise will be at 6:51 AM, solar noon will be at 11:53 a.m. when the Sun will reach its maximum altitude of 32.4 degrees, sunset will be at 4:54 p.m., and evening twilight will end at 5:55 p.m.
This should be a good season for Saturn viewing, especially through a backyard telescope. Saturn was at its closest and brightest the night of September 7. It will be shifting west each evening, making it higher in the sky and friendlier for evening viewing (particularly for children with earlier bedtimes). Through a telescope you should be able to see Saturn’s bright moon Titan and its rings. The rings are appearing thinner and will be edge-on to the Earth by early 2025. We won’t get the “classic” view of Saturn with its rings again until 2026.
Comets
Two comets might be visible during this lunar cycle. For both of these comets I recommend paying attention to the news and checking out local astronomy websites, as we should have better forecasts of how these comets are behaving as we get closer to the opportunities for prime viewing. Particularly for the newly discovered Comet C/2024 S1 (ATLAS), others (with newer information and better modeling tools) should be able to provide better guidance on when and where to look.
Comet C/2023 A3 (Tsuchinshan-ATLAS) has already survived its close pass by the Sun and will be its closest to the Earth on October 12 (five days before the full Moon). After its closest approach it will be in the evening sky as twilight ends. If it continues on its current brightness curve it should be visible with binoculars and (under good conditions) with the unaided eye for at least a few evenings after the 12th, dimming as it moves away from the Sun and the Earth. On October 12, as evening twilight ends (at 7:31 p.m. EDT) the comet will be 4 degrees above the western horizon to the right of Venus (at an estimated visual magnitude of 2.9). As twilight ends on October 13 it will be 10 degrees above the western horizon (magnitude 3), 12 degrees on October 14 (magnitude 3.2), 16 degrees on October 15 (magnitude 3.3), etc. Current brightness curves predict it will dim to magnitude 6.2 by the end of October (nearing the edge of visibility with the unaided eye under dark and clear conditions).
Comet C/2024 S1 (ATLAS) was discovered recently. It’s gotten a lot of attention because if it doesn’t break up as it approaches the Sun, it may become bright enough to see during the daytime. However, I want to avoid raising unrealistic expectations. From the information I’ve been able to find so far, I expect that at night this comet will only be visible with binoculars or a telescope, as its path will not bring it very close to the Earth. For the Washington, D.C. area (and similar latitudes) this comet will be above the horizon before morning twilight begins from now to October 21 as the comet falls towards the Sun. If it doesn’t break into pieces too small to see around closest approach, it should also be visible (with binoculars or a telescope) from November 2 to December 19 as the comet speeds away from the Sun.
However, it is a sungrazing comet and will be passing just a few solar radii from the surface of the Sun. This is so close that the sunlight will be more than 14,000 times brighter than at Earth. Sunlight this intense may cause it to break up and evaporate. But if it remains intact, based on the estimates I have while writing this, the comet will be bright enough to see during the daylight for about an hour or two around closest approach.
One brightness model estimates this comet will be brighter than magnitude -5 from 7:12 a.m. to 8:06 a.m. EDT. Based on this timing, Africa, Europe, and South America are best situated to see this daylight comet. From the East Coast of North America the comet at its brightest will be to the lower left of the Sun just after sunrise, which means we will be viewing it through more air, increasing the chance of interference from scattered sunlight and clouds.
To look for this comet during the short period when it is very close to the Sun, find out for your location which side of the Sun the comet will be on, then find something to block the Sun (e.g., a house or building, etc., the farther away the better) so you can look for the comet without staring at the Sun. Be careful and plan ahead, as it may be difficult to find a location that has both a clear view to the right part of the east-southeastern horizon and a large overhanging object to block the Sun while allowing you to see to the lower left of the Sun. I strongly recommend AGAINST using binoculars or a telescope because accidentally using high powered lenses to focus intense sunlight into your eyes is a blindingly bad idea.
If you are interested, here is some more background on Comet C/2024 S1 (ATLAS). Otherwise, skip this paragraph. This comet was discovered on Sept. 27, 2024, by one of the Asteroid Terrestrial-impact Last Alert System (ATLAS) telescopes in Hawaii. This comet’s orbit suggests it is part of a family of comets called Kreutz sungrazers that pass very close to the Sun. These comets are thought to be fragments of a large sungrazing comet, the Great Comet of 1106, that broke up as it swung around the Sun 918 years ago. This 1106 comet might itself be a fragment of an even larger sungrazing comet, possibly the Great Comet of 371 BC (also known as Aristotle’s Comet). This comet was so bright it cast shadows at night like the full Moon. Several other members of this comet family have been great comets, including the Great Comet of 1843 and the Great Comet of 1882. The most recent great comet from this family was Comet Ikeya–Seki in 1965. Since its launch in 1995, the Solar and Heliospheric Observatory (SOHO) satellite has observed more than 4000 smaller Kreutz sungrazers, some only a few meters across, with none of these smaller comets surviving their close pass by the Sun.
Meteor Showers
Five meteor showers are predicted to peak during this lunar cycle. Three meteor showers peak between October 18 and 24 when the light of the waning Moon will interfere, the most significant being the Orionids peaking on October 21. While the Orionids tend to be brighter than average and to peak at about 20 meteors per hour (under ideal conditions), the light of the waning gibbous Moon will make these harder to see this year, especially from our light-polluted urban areas. Two minor meteor showers will peak in early November. These showers are the Southern Taurids (peaking at 7 meteors per hour on November 5) and the Northern Taurids (peaking at 5 meteors per hour on November 12). These showers overlap to produce their highest combined rate around November 5, but this rate is low enough that seeing these meteors from urban locations will be difficult.
Evening Sky Highlights
On the evening of Thursday, Oct. 17, 2024 (the evening of the full Moon), as twilight ends (at 7:24 p.m. EDT), the rising Moon will be 9 degrees above the eastern horizon. Saturn will be 27 degrees above the southeastern horizon. Bright Venus will be 6 degrees above the west-southwestern horizon. Comet C/2023 A3 (Tsuchinshan-ATLAS) will be to the upper right of Venus at 22 degrees above the western horizon (at a visual magnitude of 3.7 if it continues to follow its current brightness curve). The bright star closest to overhead will be Deneb at 80 degrees above the northeastern horizon. Deneb (visual magnitude 1.3) is the 19th brightest star in our night sky and is the brightest star in the constellation Cygnus the swan. Deneb is one of the three bright stars of the “Summer Triangle” (along with Vega and Altair). Deneb is about 20 times more massive than our Sun but has used up its hydrogen, becoming a blue-white supergiant about 200 times the diameter of the Sun. If Deneb were where our Sun is, it would extend to about the orbit of the Earth. Deneb is about 2,600 light years from us.
As this lunar cycle progresses, Saturn and the background of stars will appear to shift westward each evening (as the Earth moves around the Sun). Bright Venus will shift to the left along the southwestern horizon in the opposite direction as the stars, passing above the bright star Antares (they will appear 3 degrees apart at their closest on October 25). October 21 will be the first evening the planet Mercury will be above the west-southwestern horizon 30 minutes after sunset (an estimate of when it will first be visible in the glow of dusk). The waxing Moon will pass by Antares on November 3, Venus on November 4, and Saturn on November 10. November 11 will be when Mercury will first appear above the horizon as twilight ends.
By the evening of Friday, November 15 (the evening of the full Moon after next), as twilight ends at 5:55 p.m. EST, the rising Moon will be 14 degrees above the east-northeastern horizon with the Pleiades star cluster 5 degrees to the lower left. The brightest planet in the sky will be Venus at 12 degrees above the southwestern horizon. Next in brightness will be Mercury at less than a degree above the west-southwestern horizon. Saturn will be 38 degrees above the south-southeastern horizon. Comet C/2023 A3 (Tsuchinshan-ATLAS) will be 39 degrees above the west-southwestern horizon, with its current brightness curve predicting it will have faded to magnitude 8, too faint to see with the unaided eye. The bright star closest to overhead will still be Deneb at 79 degrees above the northwestern horizon.
Morning Sky Highlights
On the morning of Thursday, October 17, 2024 (the morning of the full Moon), as twilight begins at 6:22 a.m. EDT, the setting Moon will be 11 degrees above the western horizon. The brightest planet in the sky will be Jupiter at 63 degrees above the west-southwestern horizon. Mars will be at 72 degrees above the south-southeastern horizon. Comet C/2024 S1 (ATLAS) will be 6 degrees above the east-southeastern horizon but will likely be too dim to be seen without a telescope (current projection, magnitude 12.7). The bright star appearing closest to overhead will be Pollux, the 17th brightest star in our night sky and the brighter of the twin stars in the constellation Gemini, at 75 degrees above the southeastern horizon. Pollux is an orange tinted star about 34 lightyears from Earth. It is not quite twice the mass of our Sun but about 9 times the diameter and 33 times the brightness.
As this lunar cycle progresses, Jupiter, Mars, and the background of stars will appear to shift westward each evening. Comet C/2024 S1 (ATLAS), visible with binoculars or a telescope, will brighten but shift lower as it races towards the Sun, with October 21 the last morning it will be above the horizon as morning twilight begins (estimated magnitude of 11.2). The waning Moon will pass by the Pleiades star cluster on October 19, Jupiter on October 21, Mars and Pollux on October 23, Regulus on October 26, and Spica on October 31. Comet C/2024 S1 (ATLAS) will pass its closest to the Sun on the morning of October 28 (when, if the sky is very clear, it might be bright enough to see in the daylight for an hour or so around 7:39 a.m.). If this comet survives its close pass by the Sun, it may reemerge in the morning sky. November 2 will be the first morning it will be above the horizon as morning twilight begins (with an estimated magnitude of 10.5, visible with binoculars or a telescope).
By the morning of Friday, November 15 (the morning of the full Moon after next), as twilight begins (at 5:51 a.m. EST), the setting full Moon will be 7 degrees above the west-northwestern horizon. The brightest planet in the sky will be Jupiter at 35 degrees above the western horizon. Mars will be at 68 degrees above the southwestern horizon. Comet C/2024 S1 (ATLAS) will be 13 degrees above the southeastern horizon (estimated magnitude 14.2). The bright star appearing closest to overhead will still be Pollux at 69 degrees above the west-southwestern horizon (higher than Mars by about a half degree).
Detailed Daily Guide
.Here for your reference is a day-by-day listing of celestial events between now and the full Moon on October 17, 2024. The times and angles are based on the location of NASA Headquarters in Washington, D.C, and some of these details may differ for where you are (I use parentheses to indicate times specific to the D.C. area). If your latitude is significantly different than 39 degrees north (and especially for my Southern Hemisphere readers), I recommend using an astronomy app or a star-watching guide from a local observatory, news outlet, or astronomy club.
Saturday morning, October 12: At 11:10 a.m. EDT, Comet C/2023 A3 (Tsuchinshan-ATLAS) will be at its closest to Earth. Although it will be on the horizon as evening twilight ends the evening before (Friday), it may be hard to see. Our first chance to see it above the horizon as evening twilight ends (at 7:31 PM) will likely be Saturday evening, when the comet will be 4 degrees above the western horizon, similar in altitude and to the right of Venus.
As of September 28 this comet is still following a brightness curve that predicts it to be quite bright near closest approach and remain visible to unaided human eyes (under clear dark sky conditions) through the end of October. How bright the comet will be and how quickly it actually dims will depend upon the gas and dust it is giving off, which can vary quickly and unpredictably, but it should be an impressive show in the evenings after October 12.
The comet will likely dim as it moves away from the Earth, but also appear higher in the sky and set later each evening, giving us more time and darker skies to look for it. As evening twilight ends on October 13 it will be 10 degrees above the western horizon, 12 degrees on October 14, 16 degrees on October 15, etc. Current brightness curves predict it will still be around magnitude 6 by the end of October (still visible to the unaided eye under good conditions).
Monday evening, October 14: The planet Saturn will appear near the waxing gibbous Moon. As evening twilight ends (at 7:28 p.m. EDT) Saturn will be 4 degrees to the upper right. The Moon will reach its highest for the night about 3.5 hours later (at 10:53 p.m.) with Saturn 5 degrees to the lower right. The pair will continue to separate, with Saturn setting first 5 hours after that (at 4:09 a.m.). For parts of Southern Asia and Africa the Moon will block Saturn from view.
Wednesday evening, October 16: At 8:57 p.m. EDT (CSG 8:47), the Moon will be at perigee, its closest to the Earth for this orbit.
As mentioned above, the full Moon will be Thursday morning, Oct. 17, at 7:26 a.m. EDT. This will be late Wednesday night for the International Date Line West time zone and early Friday morning from New Zealand Time eastwards to the International Date Line. This will be the third of four consecutive supermoons (and the brightest by a tiny margin). The Moon will appear full for about 3 days around this time, from Tuesday evening through Friday morning.
Saturday night into Sunday morning, October 19 to 20: The Pleiades star cluster will appear near the waning gibbous Moon. At moonrise (7:42 p.m. EDT) on the east-northeastern horizon the Pleiades will be 3 degrees to the upper right. By the time the Moon reaches its highest for the night at 3:28 a.m., the Pleiades will be 7 degrees to the lower right.
Sunday night into Monday morning, October 20 to 21: The planet Jupiter will appear near the waning gibbous Moon. As Jupiter rises on the east-northeastern horizon at 9:08 p.m. EDT, it will be 6 degrees to the lower right of the Moon. As the Moon reaches its highest in the sky at 4:29 a.m., Jupiter will be 6 degrees below the Moon, and it will be to the lower left by the time morning twilight begins at 6:26 a.m.
As mentioned above, the Orionid meteor shower will peak the early morning of Monday, October 21. Conditions are not good as moonlight will interfere with seeing these meteors, but if you happen to be out keep an eye on the sky, as you might see a meteor or two.
For the Washington DC area and similar latitudes, Monday morning, October 21: This will be the last morning Comet C/2024 S1 (ATLAS), visible with binoculars or a telescope (estimated magnitude 11.2), will be above the horizon as morning twilight begins (at 6:27 AM EDT) as it rushes towards its close passage by the Sun a week later.
Monday evening, October 21: This will be the first evening the planet Mercury will be above the west-southwestern horizon 30 minutes after sunset (an estimate of when it will start being visible in the glow of dusk).
Tuesday night into Wednesday morning, October 22 to 23: The waning gibbous Moon, the bright star Pollux, and the planet Mars will form a triangle in the night sky. As Pollux rises on the northeastern horizon at 11 p.m. EDT, it will be 8 degrees to the lower left of the Moon. Mars will rise below the Moon 30 minutes later at 11:30 p.m. As the Moon reaches its highest for the night and morning twilight begins at 6:28 a.m., Pollux will be 4 degrees to the upper left and Mars will be 7 degrees to the lower left of the Moon.
Thursday morning, October 24: The waning Moon will appear half-full as it reaches its last quarter at 4:03 a.m. EDT.
If you find you are having trouble waking up in late October and early November, the dark mornings may be the reason (or at least a plausible excuse). Since 2007 when Congress moved the start of Daylight Saving Time from the end of October to the beginning of November, the latest sunrises of the year have been in late October and early November. In 2024, for the Washington, D.C. area and similar latitudes, the time of sunrise (in EDT) from Thursday, October 24 to Saturday, November 2 will be later than the latest sunrise of winter at 7:27 a.m. EST on January 5.
In the evening sky during this lunar cycle the bright planet Venus will be shifting to the upper left along the southwestern horizon in the opposite direction as the background of stars.
Friday, October 25: This will be when Venus and the bright star Antares will pass at their closest, with Antares 3 degrees to the lower left of Venus.
Saturday morning, October 26: The bright star Regulus will appear below the waning crescent Moon. As Regulus rises on the east-northeastern horizon at 2:15 a.m. EDT, it will be 5 degrees below the Moon. Morning twilight will begin more than 4 hours later at 6:31 a.m. with Regulus 4 degrees to the lower right of the Moon.
Monday morning, October 28: At about 7:39 a.m. EDT, Comet C/2024 S1 (ATLAS) will pass its closest to the Sun. If the sky is very clear, it might be bright enough to see in the daylight for an hour or so around closest approach. For the Washington, D.C. area, closest approach will only be 7 minutes after sunrise, so our only chance of seeing this is if the sky on the east-southeastern horizon is unusually clear. The comet will be to the lower left of the Sun, and since the tail points away from the Sun, it may be hidden by the horizon until the comet rises higher in the sky. Europe, Africa, and South America are better positioned to look for this comet near the Sun. Be careful and plan ahead, as it may be difficult to find a location that has both a clear view to the right part of the east-southeastern horizon and a large overhanging object to block the Sun while allowing you to see to the lower left of the Sun.
Pay attention to the news as the predictions may change, but the brightness predictions I have as of writing this are that this comet will be brighter than magnitude -5 until 8:06 a.m. (when the Sun will be 5.6 degrees above the horizon). Magnitude -4 is generally considered the brightness limit for visibility of an object during the day, and the comet is predicted to be above this magnitude until 8:39 AM, but because it will be close to the Sun it is hard to say what the actual visibility limit will be, as the glare near the Sun depends on atmospheric conditions and can be quite bright.
Tuesday, October 29: At 6:51 p.m. EDT, the Moon will be at apogee, its farthest from the Earth for this orbit.
Thursday morning, October 31: You might be able to see the thin, waxing crescent Moon low on the east-southeastern horizon 3.5 degrees to the lower left of the bright star Spica. You will need to look for them in the glow of dawn, as the Moon will rise at 6:43 a.m. EDT 7 minutes after twilight begins at 6:36 a.m.
Thursday, October 31, is Halloween: We currently divide the year into four seasons based upon the solstices and equinoxes, with winter beginning on the winter solstice in December. This approximates winter as the quarter of the year with the coldest temperatures. Much of pre-Christian northern Europe celebrated “cross-quarter days” halfway between the solstices and equinoxes, and divided the seasons on these days. Using this older definition, winter was the quarter of the year with the shortest daily periods of daylight, with autumn ending and winter beginning on Samhain, traditionally celebrated on October 31st or November 1st (the middle of our fall). Our Halloween customs are thought to have come from these earlier celebrations of fall’s end and winter’s start.
Friday morning, November 1, at 8:47 AM EDT: This will be the new Moon, when the Moon passes between the Earth and the Sun and will not be visible from the Earth. This new Moon is considered the darkest night of the Hindu lunisolar calendar. Diwali or Divali, also known as Dipawali or Deepavali, is an important five or six day festival of lights centered on this new Moon, celebrated by Hindus and other faiths including Jains, Sikhs, and Newar Buddhists. The name comes from the row (avali) of clay lamps (deepa) celebrants light to symbolize the inner light that protects from spiritual darkness. Lakshmi Puja or Kali Puja, venerating the goddess of prosperity, Lakshmi, is the central day of the festival (November 1 this year). It is a public holiday in many countries with large Hindu, Sikh, and/or Jain populations, including Fiji, Guyana, India, Malaysia, Mauritius, Myanmar, Nepal, Pakistan, Singapore, Sri Lanka, Suriname, and Trinidad and Tobago.
The day of or the day after the New Moon: This marks the start of the new month for most lunisolar calendars. The tenth month of the Chinese year of the Dragon starts on Friday, November 1. Sundown on Friday, November 1, marks the start of Marcheshvan in the Hebrew calendar, a name often shortened to Cheshvan or Heshvan.
If Comet C/2024 S1 (ATLAS) survives its close pass by the Sun, Saturday, November 2, will be the first morning it will be above the horizon as morning twilight begins at 6:38 a.m. EDT, appearing with an estimated magnitude of 10.5 (only visible with binoculars or a telescope).
Because of Daylight Saving Time, Saturday morning, November 2, will be the latest sunrise of the year. Morning twilight will begin at 6:38 a.m. EDT, sunrise will be at 7:37 a.m., solar noon will be at 12:51 p.m. when the Sun will reach its maximum altitude of 35.1 degrees, sunset will be at 6:06 p.m., and evening twilight will end at 7:05 p.m.
In the Islamic calendar the months traditionally start with the first sighting of the waxing crescent Moon. Many Muslim communities now follow the Umm al-Qura Calendar of Saudi Arabia, which uses astronomical calculations to start months in a more predictable way. Using this calendar, sundown on Saturday, November 2, will probably mark the beginning of Jumādā al-ʾŪlā.
Early on Sunday morning, November 3: We “Fall Back” from 1:59 a.m. EDT to 1 a.m. EST. While most of us will be gaining an hour of sleep, if you want to do something for 2 hours but are only supposed to do it for one, consider doing it for the “clock hour” from 1 a.m. EDT to 2 a.m. EST. Be careful though, as about twice as many accidents tend to happen during this “clock hour” compared to other mornings of the year! Regardless, on Sunday morning you will need to reset any clocks that didn’t reset themselves! On Sunday, twilight will begin at 5:39 a.m. EST, sunrise will be at 6:38 a.m., solar noon will be at 11:51 a.m. when the Sun will reach its maximum altitude of 35.8 degrees, sunset will be at 5:05 p.m., and evening twilight will end at 6:04 p.m.
It may be difficult to see, but on Sunday evening, November 3, the bright star Antares will appear 2 degrees above the thin, waxing crescent Moon. You will need to look for the Moon in the glow of dusk as it will set on the southwestern horizon just 1 minute after evening twilight ends (at 6:04 p.m. EST).
Monday evening, November 4: The bright planet Venus will appear 4 degrees to the upper right of the thin, waxing crescent Moon. The Moon will be 6 degrees above the southwestern horizon as evening twilight ends at 6:03 p.m. EST, and will set first 46 minutes later at 6:49 p.m.
Tuesday morning, November 5: Two minor meteor showers, the Southern Taurids (peaking at 7 meteors per hour on November 5) and the Northern Taurids (peaking at 5 meteors per hour on November 12), overlap to produce their highest combined rate. Although the light of the waxing crescent Moon will not interfere, even this combined rate will be low enough to make seeing these meteors from urban areas difficult due to light pollution. Still, if you are out after midnight and the sky is clear, you might see a meteor or two.
Early Saturday morning, November 9: The Moon will appear half-full as it reaches its first quarter at 12:56 a.m. EST.
In the evenings during much of this lunar cycle, the planet Mercury will be shifting to the upper left along the southwestern horizon, moving in the opposite direction from the background of stars. On Saturday and Sunday evenings, November 9 and 10, Mercury and the bright star Antares will pass their closest, less than 2 degrees apart, with Antares to the lower left of Mercury. You will need to look low on the southwestern horizon while dusk is in the sky, as they both will have set by the time evening twilight ends.
Saturday evening into early Sunday morning, November 9 to 10: The planet Saturn will appear near the waxing gibbous Moon. As evening twilight ends at 5:58 p.m. EST, Saturn will be 2 degrees to the upper left. The Moon will reach its highest point for the night about 1 hour 45 minutes later at 7:43 p.m., with Saturn 1 degree to the upper left. For the Washington, D.C. area, Saturn will be at its closest, about 0.1 degree to the upper right of the Moon, at about 9:55 p.m. (times and angles will differ for different locations). For the southern tip if Florida and parts of the Caribbean, Central America, and Northwestern South America, the Moon will block Saturn from view. The Moon will continue passing by Saturn, with Saturn setting first on the western horizon a little less than 3.5 hours later at 1:19 a.m.
Monday evening, November 11: This will be the first evening that the planet Mercury will be above the west-southwestern horizon as evening twilight ends at 5:57 p.m. EST.
Thursday morning, November 14: At 6:18 EST, the Moon will be at perigee, its closest to the Earth for this orbit.
The full Moon after next will be Friday afternoon, November 15, 2024 at 4:29 PM EST. This will be early Saturday morning from Kamchatka and Fiji Time eastwards to the International Date Line. This will be the last of four consecutive supermoons. The Pleiades star cluster will appear near the full Moon. The Moon will appear full for about three days around this time, from a few hours before sunrise Thursday morning into a few hours before sunrise Sunday morning.
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By Space Force
U.S. Space Force senior leaders discussed the Personnel Management Act during a panel at the Air and Space Force’s Air, Space and Cyber Conference at National Harbor, Maryland, Sept. 18.
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By NASA
Skywatching Skywatching Home Eclipses What’s Up Explore the Night Sky Night Sky Network More Tips and Guides FAQ 23 Min Read The Next Full Moon is a Partial Lunar Eclipse; a Supermoon; the Corn Moon; and the Harvest Moon
The Next Full Moon is a Partial Lunar Eclipse; a SuperMoon; the Corn Moon; the Harvest Moon; the Fruit or Barley Moon; the end of Ganesh Chaturthi and the start of Pitru Paksha; Madhu Purnima; the Mid-Autumn, Mooncake, or Reunion Festival Moon; Chuseok; and Imomeigetsu or the Potato Harvest Moon.
The full Moon will be Tuesday night, September 17, 2024, at 10:35 PM EDT. This will be on Wednesday from Newfoundland and Greenland Time eastward across Eurasia, Africa, and Australia to the International Date Line. Most commercial calendars will show this full Moon on Wednesday based on Greenwich or Universal Time. The Moon will appear full for about three days, from Monday evening through Thursday morning.
This will be a partial lunar eclipse. The Moon will start entering the Earth’s partial shadow at 8:41 PM EDT. The slight dimming of the Moon will be difficult to notice until the top edge of the Moon starts entering the full shadow at 10:13 PM. The peak of the eclipse will be at 10:44 PM with only the top 8 percent of the Moon in full shadow. The Moon will finish exiting the full shadow at 11:16 PM and the partial shadow on Wednesday morning at 12:47 AM.
The phases of the Moon for September 2024. NASA/JPL-Caltech This will be a supermoon. The term “supermoon” was coined by astrologer Richard Nolle in 1979 as either a new or full Moon that occurs when the Moon is within 90% of its closest to Earth. Since we can’t see new Moons, what has the public’s attention are full supermoons, the biggest and brightest Moons of the year. Although different publications use different thresholds for deciding which full Moons qualify, most agree this will be the second of four consecutive supermoons (effectively tied with the full Moon in October for the closest of the year).
The Maine Farmer’s Almanac first published “Indian” names for the full Moons in the 1930s and these names have become widely known and used. According to this almanac, as the full Moon in September the Algonquin tribes in what is now the northeastern USA called this the Corn Moon, as this was the time for gathering their main staple crops of corn, pumpkins, squash, beans, and wild rice.
As the full Moon closest to the autumnal equinox, this is the Harvest Moon. The first known written use of this name in the English language (per the Oxford English Dictionary) was in 1706. During the fall harvest season farmers sometimes need to work late into the night by moonlight. On average moonrise is about 50 minutes later each night. Around the Harvest Moon this time is shorter, about 25 minutes for the latitude of Washington, DC, and only 10 to 20 minutes farther north in Canada and Europe.
Other European names for this full Moon are the Fruit Moon, as a number of fruits ripen as the end of summer approaches, and the Barley Moon, from the harvesting and threshing of barley.
For Hindus, this full Moon marks the end of Ganesh Chaturthi and the start of Pitru Paksha. Ganesh Chaturthi (also called Vinayaka Chaturthi or Vinayaka Chavithi) is a 10 or 11 day festival honoring the god Ganesha that ends with this full Moon. Ganesha is easily recognized by his elephant head and is worshiped as the god of beginnings, wisdom, arts and sciences, and as the remover of obstacles. Throughout the festival celebrants offer food, sweets, and prayers to clay statues of Ganesha at home and on public stages. Traditions include chanting of Vedic hymns and Hindu texts, prayers, and fasting. On the last day (near the full Moon), people carry the statues to a nearby river or ocean and immerse them. As the clay dissolves, Ganesha is believed to return to his parents, the god Shiva and goddess Parvati, on Mount Kailash.
Pitru Paksha (fortnight of the ancestors) is a 15 days long festival that ends with the new Moon. During this time, Hindus honor their ancestors (pitrs) with rituals, food offerings, and scripture reading. Pitru Paksha is also known by a number of other names.
For some Buddhists in Bangladesh and Thailand this full Moon is Madhu Purnima, the Honey Full Moon Festival or the Honey-offering Festival. The legend is that when the Buddha was trying to bring peace between two factions in a forest, an elephant and a monkey fed him, with the elephant offering fruit and the monkey offering a honeycomb.
In China, Vietnam, and some other Asian countries, this full Moon corresponds with the Mid-Autumn Festival, a traditional harvest festival. In China, other names for this festival include the Moon Festival, the Mooncake Festival, and the Reunion Festival (with wives visiting their parents then returning to celebrate with their husbands and his parents). Part of the festival includes offerings to the Moon Goddess Chang’e (the name the China National Space Agency gives their lunar missions).
In Korea, this full Moon corresponds with the harvest festival Chuseok, during which Koreans return to their traditional hometowns to pay respect to the spirits of their ancestors.
This full Moon corresponds with the first of two Japanese Tsukimi or “Moon-Viewing” festivals, also called Imomeigetsu (which translates as “potato harvest Moon”) because of the tradition of offering sweet potatoes to the Moon. These festivities have become so popular that they are often extended for several days after the full Moon.
In many traditional Moon-based calendars the full Moons fall on or near the middle of each month. This full Moon is near the middle of the eighth month of the Chinese year of the Dragon and Rabi’ al-Awwal in the Islamic calendar, the month in which many Muslims celebrate Mawlid, the birth of the Prophet Muhammad. This full Moon is near the middle of Elul in the Hebrew calendar. Elul is a time of preparation for the High Holy Days of Rosh Hashanah and Yom Kippur. Customs include granting and asking others for forgiveness as well as beginning or ending all letters with the wish that the recipient will have a good year.
As usual, the wearing of suitably celebratory celestial attire is encouraged in honor of the full Moon. Go out and observe the Moon, enjoy this harvest season (including corn, fruit, and sweet potatoes, and honey), remember your ancestors, stay in touch with your parents, and forgive and ask forgiveness. Here’s wishing you a good year!
Comet C/2023 A3 (Tsuchinshan-ATLAS)
Pay attention to the news about Comet C/2023 A3 (Tsuchinshan-ATLAS)! There are a number of “ifs” so we don’t like to raise expectations. Similar visitors from the Oort Cloud have broken apart and fizzled out as they passed close to the Sun. If this comet survives its passage by the Sun (closest approach on September 27, 2024) and if the amount of gas and dust it gives off does not decrease significantly, this might be one of the best comets in a long time. If it strongly scatters sunlight towards the Earth it might even be visible in the glow of dusk just after its closest approach to Earth on October 12.
From the Washington, DC area and similar latitudes, this comet will be above the horizon before morning twilight begins from September 22 through October 4, with the current brightness curve predicting a steady increase in brightness from about visual magnitude 4 to near 3 (the smaller the number, the brighter the object). As it brightens it may be visible under dark sky conditions and even more impressive through binoculars or a telescope, although towards the start and end of this period it may be too low on the horizon to see when the sky is completely dark.
Between about October 4 and October 11 the Sun’s glare will mask visibility from the Northern Hemisphere. Check your local news or web sites for viewing information for your latitude. For example, Sky and Telescope reports that Southern Hemisphere skywatchers should fare better.
Comet C/2023 A3 (Tsuchinshan-ATLAS) will be at its closest to Earth on October 12 at 11:10 AM EDT. Around closest approach the comet’s brightness is predicted to peak at about visual magnitude 3 (similar to many stars). Forward scattering might increase the brightness significantly, possibly as high as -1 (brighter than every star except Sirius). How bright the comet actually appears will depend upon how much gas and dust it is giving off, which can change quickly. Also, brightness comparisons between comets and stars can be misleading as the light of the comet is spread out making it less distinct than a star with the same brightness.
The best time to look should be the evenings on and shortly after October 12 with the comet above the western horizon after sunset. The evening of October 12 the comet will be 4 degrees above the western horizon as evening twilight ends, similar in altitude and to the right of Venus. The comet is expected to dim as it moves away from the Earth, but will appear higher in a darker sky and set later each evening, which could make it easier to see. As evening twilight ends on October 13 it will be 10 degrees above the western horizon, 12 degrees on October 14, 16 degrees on October 15, etc. The brightness will decrease to about magnitude 6 by the end of October.
Meteor Showers
During this lunar cycle four minor meteors showers are predicted to peak at 5 or fewer visible meteors per hour (under ideal viewing conditions), making them basically not visible from our light-polluted urban areas.
Evening Sky Highlights
On the evening of Tuesday, September 17 (the evening of the full Moon), as twilight ends (at 8:10 PM EDT), the rising Moon will be 11 degrees above the east-southeastern horizon with Saturn to the upper right at 14 degrees above the horizon. Later in the evening the partial shadow of the Earth will cover a small upper part of the Moon. Bright Venus will be 2 degrees above the west-southwestern horizon with the star Spica on the horizon to the lower left. The bright star closest to overhead will be Vega, the brightest star in the constellation Lyra the lyre, at 87 degrees above the western horizon. Vega is part of the Summer Triangle along with Deneb and Altair. It is the 5th brightest star in our night sky, about 25 light-years from Earth, has twice the mass of our Sun, and shines 40 times brighter than our Sun.
As this lunar cycle progresses, Saturn and the background of stars will appear to shift westward each evening (as the Earth moves around the Sun). Bright Venus will shift to the left along the west-southwestern horizon, appearing slightly higher each evening. The waxing Moon will pass by Venus on October 5, Antares on October 7, and Saturn on October 14. Comet C/2023 A3 (Tsuchinshan-ATLAS) will be at its closest to Earth on October 12 at 11:10 AM. Assuming it survives its pass by the Sun on September 27 and depending upon how much gas and dust it gives off, it could be a good show in the evenings on and after October 12. See the comet summary above and keep an eye on the news for updates on this comet.
By the evening of Thursday, October 17 (the evening of the full Moon after next), as twilight ends (at 7:24 PM EDT), the rising Moon will be 9 degrees above the eastern horizon. Saturn will be 27 degrees above the southeastern horizon. Bright Venus will be 6 degrees above the west-southwestern horizon. Comet C/2023 A3 (Tsuchinshan-ATLAS) will be 22 degrees above the western horizon. The bright star closest to overhead will be Deneb at 80 degrees above the northeastern horizon. Deneb is the 19th brightest star in our night sky and is the brightest star in the constellation Cygnus the swan. Deneb is one of the three bright stars of the “Summer Triangle” (along with Vega and Altair). Deneb is about 20 times more massive than our Sun but has used up its hydrogen, becoming a blue-white supergiant about 200 times the diameter of the Sun. If Deneb were where our Sun is, it would extend to about the orbit of the Earth. Deneb is about 2,600 light years from us.
Morning Sky Highlights
On the morning of Wednesday, September 18 (the morning of the night of the full Moon), as twilight begins (at 5:55 AM EDT), the setting full Moon will be 15 degrees above the west-southwestern horizon. The brightest planet in the sky will be Jupiter at 71 degrees above the south-south eastern horizon. Near Jupiter will be Mars at 61 degrees above the east-southeastern horizon. Saturn will be below the Moon at 1 degree above the western horizon. The bright star appearing closest to overhead will be Capella, the brightest star in the constellation Auriga the charioteer, at 80 degrees above the northeastern horizon. Although we see Capella as a single star (the 6th brightest in our night sky), it is actually four stars (two pairs of stars orbiting each other). Capella is about 43 lightyears from us.
As this lunar cycle progresses, Jupiter, Mars, Saturn, and the background of stars will appear to shift westward each evening. After September 19 Saturn set before morning twilight begins. The waning Moon will pass by the Pleiades star cluster on September 22, Mars on September 25, Pollux on September 26, and Regulus on September 29. Comet C/2023 A3 (Tsuchinshan-ATLAS) will be above the horizon before morning twilight begins from September 22 through October 4. Comets are notoriously difficult to predict, but if the amount of gas and dust it gives off remains constant it should increase in brightness each morning. See the comet summary above and keep an eye on the news for updates on this comet.
By the morning of Thursday, October 17 (the morning of the full Moon after next), as twilight begins (at 6:22 AM EDT), the setting full Moon will be 11 degrees above the western horizon. The brightest planet in the sky will be Jupiter at 63 degrees above the west-southwestern horizon. Mars will be at 72 degrees above the south-southeastern horizon. The bright star appearing closest to overhead will be Pollux, the 17th brightest star in our night sky and the brighter of the twin stars in the constellation Gemini, at 75 degrees above the southeastern horizon. Pollux is an orange tinted star about 34 lightyears from Earth. It is not quite twice the mass of our Sun but about 9 times the diameter and 33 times the brightness.
Detailed Daily Guide
Here for your reference is a day-by-day listing of celestial events between now and the full Moon on October 17, 2024. The times and angles are based on the location of NASA Headquarters in Washington, DC, and some of these details may differ for where you are (I use parentheses to indicate times specific to the DC area). If your latitude is significantly different than 39 degrees north (and especially for my Southern Hemisphere readers), I recommend using an astronomy app or a star-watching guide from a local observatory, news outlet, or astronomy club.
Saturday night, September 14, is International Observe the Moon Night! See https://moon.nasa.gov/observe-the-moon-night/about/overview/ for more information.
Our 24 hour clock is based on the average length of the solar day. Solar noon on Sunday, September 15 to solar noon on Monday, September 16, will be the shortest solar day of the year, 23 hours, 59 minutes, and 38.6 seconds long.
Monday night into Tuesday morning, September 16 to 17, Saturn will appear near the full Moon. As evening twilight ends (at 8:12 PM EDT) Saturn will be 6 degrees to the left of the Moon. When the Moon reaches its highest for the night (at 12:17 AM) Saturn will be 4 degrees to the upper left. By the time morning twilight begins (at 5:54 AM) the Moon will be 1 degree above the west-southwestern horizon with Saturn 1 degree above the Moon. For parts of western North America and across the Pacific Ocean towards Australia the Moon will pass in front of Saturn. See http://lunar-occultations.com/iota/planets/0917saturn.htm for a map and information on the areas that will see this occultation.
Tuesday morning, September 17, will be the last morning that Mercury will be above the horizon as morning twilight begins (at 5:54 AM EDT).
As mentioned above, the full Moon will be Tuesday night, September 17, at 10:35 PM EDT. This will be on Wednesday from Newfoundland and Greenland Time eastward across Eurasia, Africa, and Australia to the International Date Line. Most commercial calendars are based on Greenwich or Universal Time and will show this full Moon on Wednesday. The Moon will appear full for about three days from Monday evening through Thursday morning.
This will be a partial lunar eclipse. The Moon will start entering the partial shadow of the Earth at 8:41 PM EDT. The slight dimming of the Moon will be difficult to notice until the top edge of the Moon starts entering the full shadow at 10:13 PM. The peak of the eclipse will be at 10:44 PM with just the top 8.4% of the Moon in full shadow. The Moon will finish exiting the full shadow at 11:16 PM and the partial shadow on Wednesday morning at 12:47 AM.
This will be the second of four consecutive supermoons, appearing larger than last month’s supermoon and effectively tied with the full Moon in October for the closest full Moon of the year.
Tuesday and Wednesday evenings, September 17 and 18, the star Spica will appear a little over 2 degrees from the bright planet Venus. On Tuesday evening as evening twilight ends (at 8:10 PM EDT) Spica will be to the lower left of Venus and on the verge of setting on the west-southwestern horizon. Wednesday evening Spica will be a few hundredths of a degree closer and will appear below Venus, but will set about 2 minutes before evening twilight ends.
Wednesday morning September 18, at 9:29 AM EDT, the Moon will be at perigee, its closest to the Earth for this orbit.
Thursday morning, September 19, will be the last morning the planet Saturn will be above the western horizon as morning twilight begins.
If you are interested in spotting the planet Neptune through a telescope, Friday evening, September 20, will be when it will be at its closest and brightest for the year. Neptune will reach its highest in the sky early Saturday morning (at 1:02 AM EDT).
Saturday night into Sunday morning, September 21 to 22, the Pleiades star cluster will appear near the waning gibbous Moon. The Pleiades will be 5 degrees to the lower left as they rise on the east-northeastern horizon (at 9:23 PM EDT), 1.5 degrees to the upper left by the time the Moon reaches its highest for the night (at 4:44 AM), and less than 1 degree to the upper left as morning twilight begins (at 5:59 AM). The Moon will actually pass through the Pleiades (at about 8 AM) when daylight will mask these stars from view.
Sunday morning, September 22, will be the first morning Comet C/2023 A3 (Tsuchinshan-ATLAS) will be above the horizon before morning twilight begins, with the current brightness curve predicting it at visual magnitude 4. Unless it breaks apart, this comet is likely to brighten each morning until October 4 (after which it will no longer be above the horizon before twilight begins).
Sunday morning, September 22, at 8:44 AM EDT, will be the autumnal equinox, the astronomical end of summer and start of fall.
Monday night into Tuesday morning, September 23 to 24, the bright planet Jupiter will appear to the lower right of the waning half-full Moon. Jupiter will be 6 degrees to the lower right as it rises on the east-northeastern horizon (at 10:54 PM EDT). Jupiter will shift slightly clockwise as it moves away from the Moon.
Thursday afternoon, September 24, the waning Moon will appear half-full as it reaches its last quarter at 2:50 PM EDT (when we can’t see it).
Wednesday morning, September 25, the planet Mars will appear below the waning crescent Moon. Mars will be 6 degrees below the Moon as it rises on the east-northeastern horizon (at 12:16 AM EDT). Mars will be 5 degrees to the lower right as morning twilight begins (at 6:01 AM).
Thursday morning, September 26, the star Pollux (the brighter of the twin stars in the constellation Gemini the twins) will appear near the waning crescent Moon. Pollux will be 3 degrees to the lower left as it rises on the northeastern horizon (at 12:47 AM EDT) and will be 2 degrees to the upper left by the time morning twilight begins (at 6:02 AM).
Friday afternoon, September 27, at around 2 PM EDT, Comet C/2023 A3 (Tsuchinshan-ATLAS) will be at its closest to the Sun. This comet has an inbound orbital period of millions of years and may gain enough energy from this flyby of the Sun to leave the solar system forever.
Sunday morning, September 29, the star Regulus will appear near the waning crescent Moon. As Regulus rises on the east-northeastern horizon (at 4:01 AM EDT) it will be 2.5 degrees to the lower right of the Moon. Morning twilight will begin 2 hours later (at 6:05 AM) with Regulus 3 degrees to the right.
Monday afternoon, September 30, the planet Mercury will be passing on the far side of the Sun as seen from the Earth, called superior conjunction. Because Mercury orbits inside of the orbit of Earth, it will be shifting from the morning sky to the evening sky and will begin emerging from the glow of twilight on the west-southwestern horizon towards the end of October (depending upon viewing conditions).
Wednesday, October 2, at 2:46 PM EDT, will be the new Moon, when the Moon passes between the Earth and the Sun and is usually not visible. For much of the Pacific Ocean as well as the southern part of South America, part of Antarctica, and a thin slice of the southwestern Atlantic, the Moon will block some of the Sun in a partial eclipse. For a narrow strip from the Pacific south of the Hawaiian Islands across the Pacific, part of Chile and Argentina, and into the southwestern Atlantic Ocean, the Moon will actually pass in front of the Sun, blocking most of it from view in an annular solar eclipse. Because the Moon will be at apogee (its farthest from the Earth) just 70 minutes later (at 3:56 PM) it will not block the entire Sun from view and this will not be a total solar eclipse.
The day of or the day after the New Moon marks the start of the new month for most lunisolar calendars. Sundown on Wednesday, October 2, will be the start of Rosh Hashanah (the Head of the Year), the two-day Jewish New Year celebration that will end at sundown on Friday, October 4. Rosh Hashanah is the first of a series of holidays in Tishrei, the first month of the Hebrew calendar. The tenth day of Tishrei is Yom Kippur, the Day of Atonement. The 10 days from Rosh Hashanah to Yom Kippur, called the Days of Awe, are a time to reflect on the mistakes of the past year and make resolutions for the new year. The fifteenth day of Tishrei (close to the full Moon after next) is the start of the 7-day Sukkot holiday.
The ninth month of the Chinese year of the Dragon starts on Thursday, October 3.
In the Islamic calendar the months traditionally start with the first sighting of the waxing crescent Moon. Many Muslim communities now follow the Umm al-Qura Calendar of Saudi Arabia, which uses astronomical calculations to start months in a more predictable way. Using this calendar, sundown on Thursday evening, October 3, will probably mark the beginning of Rabiʽ al-Thani, also known as Rabi’ al-Akhirah.
Friday, October 4, will be the last morning Comet C/2023 A3 (Tsuchinshan-ATLAS) will be above the horizon before morning twilight begins, with the current brightness curve predicting a visual magnitude near 3, similar in brightness to many visible stars. It may be visible to the naked eye under dark sky conditions and even more impressive through binoculars or a telescope.
Saturday evening, October 5, you may be able to see the thin waxing crescent Moon 4.5 degrees to the lower left of the bright planet Venus. As evening twilight ends (at 7:41 PM EDT) the Moon will be a degree above the west-southwestern horizon. The Moon will set first 14 minutes later (at 7:55 PM).
Monday evening, October 7, the bright star Antares will appear 2 degrees to the right of the waxing crescent Moon. As evening twilight ends (at 7:38 PM EDT) the Moon will be 11 degrees above the southwestern horizon. Antares will set first about 20 minutes later (at 9 PM).
Thursday afternoon, October 10, the Moon will appear half-full as it reaches its first quarter at 2:55 PM EDT.
Saturday morning, October 12, at 11:10 AM, Comet C/2023 A3 (Tsuchinshan-ATLAS) will be at its closest to Earth. If it survives its pass by the Sun this will likely be when it will be near its brightest. Although it will be on the horizon as evening twilight ends on Friday, our first chance to see it above the horizon as it emerges from the glow of dusk likely will be Saturday evening, when the comet will be 4 degrees above the western horizon as evening twilight ends (at 7:31 PM EDT), similar in altitude and to the right of Venus. Over the next few nights the comet will likely dim as it moves away from the Earth, but also appear higher in the sky and set later each evening, giving us more time and darker skies to look for this comet. As evening twilight ends on October 13 it will be 10 degrees above the western horizon, 12 degrees on October 14, 16 degrees on October 15, etc. Current brightness curves predict it will dim quickly and will be below magnitude 6 by the end of October. How bright the comet will be and how quickly it actually dims will depend upon the gas and dust it is giving off, which can vary quickly and unpredictably, but it could be a good show in the evenings after October 12.
Monday evening, October 14, the planet Saturn will appear near the waxing gibbous Moon. As evening twilight ends (at 7:28 PM EDT) Saturn will be 4 degrees to the upper right. The Moon will reach its highest for the night about 3.5 hours later (at 10:53 PM) with Saturn 5 degrees to the lower right. The pair will continue to separate, with Saturn setting first 5 hours after that (at 4:09 AM). For parts of Southern Asia and Africa the Moon will block Saturn from view, see http://lunar-occultations.com/iota/planets/1014saturn.htm for a map and information on the areas that will acually see this occultation.
Wednesday evening, October 16, at 8:57 PM EDT, the Moon will be at perigee, its closest to the Earth for this orbit.
The full Moon after next will be Thursday morning, October 17, 2024, at 7:26 AM EDT. This will be late Wednesday night in the International Date Line West time zone and early Friday morning from New Zealand Time eastwards to the International Date Line. This will be the third of four consecutive supermoons (and the brightest by a tiny margin). The Moon will appear full for about 3 days around this time, from Tuesday evening through Friday morning.
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Skywatching Skywatching Home Eclipses What’s Up Explore the Night Sky Night Sky Network More Tips and Guides FAQ 20 Min Read The Next Full Moon is a Supermoon Blue Moon
The full moon sets over Homestead National Historic Park in Nebraska. Credits:
National Park Service/Homestead The Next Full Moon is a Supermoon, a Blue Moon; the Sturgeon Moon; the Red, Corn, Green Corn, Barley, Herb, Grain, or Dog Moon; Raksha Bandhan or Rakhi Purnima; and Tu B’Av.
The full Moon will be Monday afternoon, August 19, 2024, at 2:26 PM EDT. This will be Tuesday morning from Nepal Standard Time eastward across the rest of Asia and Australia to the International Date Line. The Moon will appear full for three days, from Sunday morning through early Wednesday morning.
This will be a supermoon. The term “supermoon” was coined by astrologer Richard Nolle in 1979 as either a new or full Moon that occurs when the Moon is within 90% of its closest approach to Earth. Since we don’t really see new Moons, what has caught the public’s attention are full supermoons as they are the biggest and brightest full Moons of the year. This will be the first of four consecutive supermoons this year (with the full Moons in September and October virtually tied for the closest of the year).
Although it will not look blue, as the third full Moon in a season with four full Moons, this will be a Blue Moon. The first recorded use of “Blue Moon” in English dates from 1528. Speculations on the origin of the term include an old English phrase that means “betrayer Moon” (because it led to mistakes in setting the dates for Lent and Easter). Or it may be a comparison to rare events such as when dust in the atmosphere makes the Moon actually appear blue. Since the 1940’s the term “Blue Moon” has also been used for the second full Moon in a month that has two full Moons.
Although it will not look blue, as the third full Moon in a season with four full Moons, this will be a Blue Moon. The first recorded use of “Blue Moon” in English dates from 1528.
Gordon Johnston
Retired NASA Program Executive
The Maine Farmer’s Almanac began publishing “Indian” names for full Moons in the 1930s and these names have become widely known and used. According to this almanac, as the full Moon in August the Algonquin tribes in what is now the northeastern USA called this the Sturgeon Moon after the large fish that were more easily caught this time of year in the Great Lakes and other major bodies of water. Other names reported for this Moon include the Red Moon, the Corn or Green Corn Moon, the Barley Moon, the Herb Moon, the Grain Moon, and the Dog Moon.
A quick note for my Southern Hemisphere readers (as I’ve heard from some recently). Many lunar names and traditions are based on the Northern Hemisphere seasons (I’m interested in learning more about southern traditions). I’ve noticed some publications shifting names like the Sturgeon Moon by 6 months (e.g., using the northern February names for August). Also, for the detailed descriptions below, instead of looking south towards the Moon and planets you will be looking north, so what I describe will be upside down. Finally, the seasons are reversed, so morning and evening twilight times, etc., will be very different.
This full Moon corresponds with the Hindu festival Raksha Bandhan, also called Rakhi Purnima, celebrating the bond between brothers and sisters. One of the traditions is for sisters of all ages to tie a rakhi (a cotton bracelet) around their brother’s wrist, receiving a gift from the brother in return as a sign of the continuing bond between them. The term “Raksha Bandhan” translates as “the bond of protection, obligation, or care.”
In many traditional Moon-based calendars the full Moons fall on or near the middle of each month. This full Moon is near the middle of the seventh month of the Chinese year of the Dragon, Safar in the Islamic calendar, and Av in the Hebrew calendar. Av corresponds with Tu B’Av, a holiday in modern Israel similar to Valentine’s Day.
For Science Fiction fans, a note on the author Theodore Sturgeon (1918-1985) in honor of the Sturgeon Moon. Theodore Sturgeon wrote mostly science fiction but some horror and mystery stories. For Star Trek fans, his scripts introduced important concepts although only “Shore Leave” and “Amok Time” were produced. He introduced “pon far,” the Vulcan hand symbol, “live long and prosper,” and the “Prime Directive” (in a script that was not produced but that influenced later scripts).
As usual, the wearing of suitably celebratory celestial attire is encouraged in honor of the full Moon. In addition, enjoy the super blue Moon, keep in touch with your siblings, and consider reading some Theodore Sturgeon.
As for other celestial events between now and the full Moon after next (with specific times and angles based on the location of NASA Headquarters in Washington, DC):
As Northern Hemisphere summer nears its end the daily periods of sunlight continue shortening, changing at their fastest around the equinox on September 22. On Monday, August 19, (the day of the full Moon), morning twilight will begin at 5:24 AM, sunrise will be at 6:26 AM, solar noon at 1:11 PM when the Sun will reach its maximum altitude of 63.6 degrees, sunset will be at 7:57 PM, and evening twilight will end at 8:58 PM. By Tuesday, September 17, (the day of the full Moon after next), morning twilight will begin at 5:54 AM, sunrise will be at 6:52 AM, solar noon at 1:02 PM when the Sun will reach its maximum altitude of 53 degrees, sunset will be at 7:12 PM, and evening twilight will end at 8:10 PM.
This should be the start of a good season for Saturn viewing, especially through a backyard telescope. Saturn will be at its closest and brightest the night of September 7. It will be shifting west each evening, making it higher in the sky and friendlier for evening viewing (particularly for children with earlier bedtimes). Through a telescope you should be able to see Saturn’s bright moon Titan and its rings. The rings are appearing thinner and will be edge-on to the Earth by early 2025. We won’t get the “classic” view of Saturn with its rings until 2026.
Meteor Showers
Two minor meteor showers are predicted to peak during this lunar cycle, both visible from the Northern Hemisphere. These are minor compared to the Perseids (which peak at 100 meteors per hour the morning of August 12). The Aurigids will peak at 10 meteors per hour the morning of August 31 and the September Epsilon Perseids at 5 meteors per hour the morning of September 9. These will be difficult to see from our light-polluted urban areas (although the Aurigids tend to be brighter meteors). If you are in a dark area with clear skies during the early mornings around these peaks, watch out for a few meteors.
The best conditions for viewing these meteors would be if the sky is clear with no clouds or high hazes, you go to a place far from any light sources or urban light pollution, and you have a clear view of a wide expanse of the sky. Give your eyes time to adapt to the dark. Your color vision near the center of your field of view will adapt in about 10 minutes. Your more sensitive black and white vision will improve for an hour or more (improving most in the first 35 to 45 minutes). Since some meteors are faint, you will tend to see more meteors from the “corner of your eye.” Even a short exposure to light (from passing car headlights, etc.) will start the adaptation over again (so no turning on a light or your cell phone to check what time it is).
Evening Sky Highlights
On the evening of Monday, August 19 (the evening of the full Moon), as twilight ends (at 8:58 PM), the rising Moon will be 7 degrees above the east-southeastern horizon. The only visible planet will be Saturn at 1.5 degrees above the eastern horizon. Bright Venus will set 4 minutes before twilight ends. Before it sets it will be bright enough to see in the glow of dusk on the western horizon. The bright star closest to overhead will be Vega, the brightest star in the constellation Lyra the lyre, at 80 degrees above the eastern horizon. Vega is part of the Summer Triangle along with Deneb and Altair. It is the 5th brightest star in our night sky, about 25 light-years from Earth, has twice the mass of our Sun, and shines 40 times brighter than our Sun.
As this lunar cycle progresses, Saturn and the background of stars will appear to shift westward each evening (as the Earth moves around the Sun). The full Moon will pass near Saturn on August 20. Bright Venus will be moving away from the Sun and after August 28 will appear above the horizon when evening twilight ends. The waxing Moon will pass by Venus on September 4 (setting before evening twilight ends), Spica on September 6, Antares on September 9 and 10, and Saturn on September 16.
By the evening of Tuesday, September 17 (the evening of the full Moon after next), as twilight ends (at 8:10 PM), the rising Moon will be 11 degrees above the east-southeastern horizon with Saturn to the upper right at 14 degrees above the horizon. Later in the evening the partial shadow of the Earth will cover a small upper part of the Moon. Bright Venus will be 2 degrees above the west-southwestern horizon with the star Spica on the horizon to the lower left. The bright object appearing closest to overhead will still be Vega at 87 degrees above the western horizon.
Morning Sky Highlights
On the morning of Monday, August 19 (the morning of the full Moon), as twilight begins (at 5:24 AM), the setting Moon will be 5 degrees above the southwestern horizon. The brightest planet in the sky will be Jupiter at 49 degrees above the eastern horizon. Near Jupiter will be Mars at 47 degrees above the horizon. Saturn will be 29 degrees above the southwestern horizon. The bright star appearing closest to overhead will be Capella, the brightest star in the constellation Auriga the charioteer, at 55 degrees above the east-northeastern horizon. Although we see Capella as a single star (the 6th brightest in our night sky), it is actually four stars (two pairs of stars orbiting each other). Capella is about 43 lightyears from us.
As this lunar cycle progresses, Jupiter, Mars, Saturn, and the background of stars will appear to shift westward each evening, with Mars moving more slowly, shifting away from Jupiter. Between August 28 and September 17 Mercury will join these planets, rising on the east-northeastern horizon. Mercury will reach its highest (as twilight begins) on September 6 and pass by the bright star Regulus on September 9. The waning Moon will pass by Saturn on August 21, the Pleiades star cluster on August 26, Jupiter on August 27 (forming a triangle with Mars), Mars on August 28, Pollux on August 30, Mercury on September 1, and the waxing full Moon will pass near Saturn on September 17.
By the morning of Wednesday, September 18 (the morning of the night of the full Moon after next), as twilight begins (at 5:55 AM), the setting full Moon will be 15 degrees above the west-southwestern horizon. The brightest planet in the sky will be Jupiter at 71 degrees above the south-south eastern horizon. Near Jupiter will be Mars at 61 degrees above the east-southeastern horizon. Saturn will be below the Moon at 1 degree above the western horizon. The bright star appearing closest to overhead will still be Capella at 80 degrees above the northeastern horizon.
Detailed Daily Guide
Here for your reference is a day-by-day listing of celestial events between now and the full Moon on September 17, 2024. The times and angles are based on the location of NASA Headquarters in Washington, DC, and some of these details may differ for where you are (I use parentheses to indicate times specific to the DC area). If your latitude is significantly different than 39 degrees north (and especially for my Southern Hemisphere readers), I recommend using an astronomy app or a star-watching guide from a local observatory, news outlet, or astronomy club.
For the Northern Hemisphere, this should be a good year for the annual Perseids (007 PER) meteor shower, which peaked the morning of Monday, August 12. Moonset will be a little before midnight on August 11 and the radiant will rise higher in the north-northern sky until the sky shows the first signs of dawn (before morning twilight begins at 5:16 AM). The peak is broad, and in past years high activity has been reported well after the peak, so keep an eye on the sky from moonset to the first hints of dawn over the next few mornings. See the meteor shower summary near the beginning of this posting for general information on viewing meteors.
Monday morning, August 12, the Moon will reach its first quarter at 11:19 AM EDT (when we can’t see it).
Tuesday night, August 13, the bright star Antares will be near the waxing gibbous Moon. Antares will be 2.5 degrees to the upper left as evening twilight ends (at 9:08 PM EDT). By moonset on the southwestern horizon (Wednesday morning at 12:30 AM) Antares will be 1 degree above the Moon. Viewers in the southern part of South America and the Antarctic Peninsula will see the Moon pass in front of Antares. See http://lunar-occultations.com/iota/bstar/0814zc2349.htm for a map and information on areas that can see this occultation.
Throughout this lunar cycle Mars will drift towards bright Jupiter. They will be at their closest on Wednesday morning, August 14, just a third of a degree apart, which should be a good show! Jupiter will rise early in the morning (at 1:18 AM EDT) on the east-northeastern horizon below Mars. They will be 45 degrees above the eastern horizon as morning twilight begins 4 hours later (at 5:18 AM).
Friday evening, August 16, will be the first evening that Saturn will be above the eastern horizon as evening twilight ends (at 9:03 PM EDT).
Sunday evening, August 18, Mercury will be passing between the Earth and the Sun as seen from the Earth, called inferior conjunction. Mercury will be shifting from the evening sky to the morning sky and will begin emerging from the glow of dawn on the east-northeastern horizon at the end of August.
As mentioned above, the full Moon will be Monday afternoon, August 19, at 2:26 PM EDT. This will be Tuesday morning from Nepal Standard Time eastward across the rest of Asia and Australia to the International Date Line. The Moon will appear full for about three days around this time, from Sunday morning through early Wednesday morning. As the third full Moon in a season with four full Moons, this will be a Blue Moon (by the older, more traditional definition). It will also be a supermoon.
Tuesday night into Wednesday morning, August 20 to 21, Saturn will be very close to the full Moon. As evening twilight ends (at 8:57 PM EDT) they will be 2 degrees above the eastern horizon with Saturn 1 degree to the upper left. They will be at their closest about an hour later. The Moon will reach its highest in the sky Wednesday morning (at 2:32 AM) with Saturn 2 degrees to the right. When morning twilight begins (at 5:26 AM) Saturn will be almost 4 degrees to the lower right of the Moon. See http://lunar-occultations.com/iota/planets/0821saturn.htm for a map and information on the areas that will actually see the Moon pass in front of Saturn.
Wednesday morning, August 21, at 1:02 AM EDT, the Moon will be at perigee, its closest to the Earth for this orbit.
Sunday night into Monday morning, August 25 to 26, the Pleiades star cluster will appear above the waning half-moon. When the Moon rises on the east-northeastern horizon (at 11:12 PM EDT) the Pleiades will be just 1 degree above the Moon. The Pleiades will be 4 degrees to the upper right as morning twilight begins (at 5:31 AM).
Monday morning, August 26, the waning Moon will appear half-full as it reaches its last quarter at 5:26 AM EDT.
Tuesday morning, August 27, bright Jupiter will appear below the waning crescent Moon. As Jupiter rises on the east-northeastern horizon (at 12:34 AM EDT) it will be 6 degrees below the Moon. By the time morning twilight begins (at 5:32 AM) Jupiter will be 5.5 degrees to the lower right of the Moon.
Wednesday morning, August 28, Mars will appear to the right of the waning crescent Moon. As Mars rises on the east-northeastern horizon (at 12:56 AM EDT) it will be 6 degrees to the right. By the time morning twilight begins (at 5:34 AM) Mars will be 8 degrees to the upper right. Wednesday morning will also be the first morning that Mercury will be above the east-northeastern horizon as morning twilight begins.
Thursday evening, August 29, will be the first evening bright Venus will be above the western horizon as evening twilight ends (at 8:42 PM EDT).
Friday morning, August 30, the bright star Pollux will be above the waning crescent Moon. When the Moon rises on the northeastern horizon (at 2:50 AM EDT) Pollux will be 3 degrees from the Moon. It will be 4 degrees from the Moon when morning twilight begins (at 5:36 AM).
Sunday morning, September 1, you may be able to see the thin, waning crescent Moon with Mercury 4.5 degrees to the lower right. Mercury will rise last (at 5:14 AM) and the Moon will be 6 degrees above the east-northeastern horizon as morning twilight begins 24 minutes later (at 5:38 AM).
Monday evening, September 2, at 9:55 PM EDT, will be the new Moon when the Moon passes between the Earth and the Sun.
The day of or the day after the New Moon marks the start of the new month for most lunisolar calendars. The eighth month of the Chinese year of the Dragon starts on Tuesday, September 3. Sundown on Tuesday marks the start of Elul in the Hebrew calendar. Elul is a time of preparation for the High Holy Days of Rosh Hashanah and Yom Kippur. Customs include granting and asking others for forgiveness as well as beginning or ending all letters with the wish that the recipient will have a good year. In the Islamic calendar the months traditionally start with the first sighting of the waxing crescent Moon. Many Muslim communities now follow the Umm al-Qura Calendar of Saudi Arabia, which uses astronomical calculations to start months in a more predictable way. Using this calendar, sundown on Tuesday evening will probably be the beginning of Rabi’ al-Awwal, the month in which many Muslims celebrate Mawlid, the birth of the Prophet Muhammad.
Wednesday evening, September 4, will be when Mercury reaches its greatest angular separation from the Sun as seen from the Earth (called greatest elongation). This is not quite the same as when Mercury will appear at its highest as morning twilight begins.
Friday morning, September 6, will be when Mercury will appear at its highest (2 degrees) above the east-northeastern horizon as morning twilight begins (at 5:43 AM EDT).
Wednesday evening, September 4, you might be able to see the thin, waxing crescent Moon near bright Venus, although you may need binoculars to find the Moon in the glow of dusk. The Moon will be 3 degrees above the western horizon 30 minutes after sunset (at 8:03 PM EDT) with Venus 5 degrees to the upper left. The Moon will set 17 minutes later (at 8:20 PM), 12 minutes before evening twilight ends (at 8:32 PM).
Thursday morning, September 5, at 10:55 AM EDT, the Moon will be at apogee, its farthest from the Earth for this orbit.
Thursday evening, September 5, the thin, waxing crescent Moon will be 7 degrees to the left of bright Venus. The Moon will be 1 degree above the western horizon as evening twilight ends (at 8:30 PM EDT) with Venus setting first 4 minutes later (at 8:34 PM).
Friday evening, September 6, the star Spica will appear 3 degrees to the left of the waxing crescent Moon. As evening twilight ends (at 8:29 PM EDT) the Moon will be 5 degrees above the west-southwestern horizon. Spica will set first 25 minutes later (at 8:54 PM). A small part of Africa will see the Moon pass in front of Spica, see http://lunar-occultations.com/iota/bstar/0906zc1925.htm for a map and information.
Saturday night, September 7, Saturn will reach its closest and brightest for the year, called “opposition” because it will be opposite the Earth from the Sun, effectively a “full” Saturn. Saturn will be 10 degrees above the east-southeastern horizon as evening twilight ends (at 8:27 PM EDT), will reach its highest in the sky Sunday morning at 1:09 AM, and will be 11 degrees above the west-southwestern horizon as morning twilight begins (at 5:45 AM).
Monday morning, September 9, will be when Mercury and the bright star Regulus will be at their closest, just 0.5 degrees apart. They will be 5 degrees above the east-northeastern horizon as morning twilight begins (at 5:46 AM EDT).
Monday evening, September 9, the star Antares will be 7 degrees to the upper left of the waxing crescent Moon. As evening twilight ends (at 8:24 PM EDT) the Moon will be 16 degrees above the southwestern horizon and it will set on the west-southwestern horizon 2 hours later (at 10:26 PM).
By Tuesday evening, September 10, the Moon will have shifted to 6 degrees to the left of Antares and the pair will separate as the evening progresses, with Antares setting first (at 10:45 PM EDT).
Wednesday morning, September 11, the Moon will appear half-full as it reaches its first quarter at 2:06 AM EDT.
Our 24 hour clock is based on the average length of the solar day. Solar noon on Sunday, September 15 to solar noon on Monday, September 16, will be the shortest solar day of the year, 23 hours, 59 minutes, and 38.6 seconds long.
Tuesday morning, September 17, will be the last morning that Mercury will be above the horizon as morning twilight begins (at 5:54 AM EDT).
Monday night into Tuesday morning, September 16 to 17, Saturn will appear near the full Moon. As evening twilight ends (at 8:12 PM EDT) Saturn will be 6 degrees to the left of the Moon. When the Moon reaches its highest for the night (at 12:17 AM) Saturn will be 4 degrees to the upper left. By the time morning twilight begins (at 5:54 AM) the Moon will be 1 degree above the west-southwestern horizon with Saturn 1 degree above the Moon. For parts of western North America and across the Pacific Ocean towards Australia the Moon will pass in front of Saturn. See http://lunar-occultations.com/iota/planets/0917saturn.htm for a map and information on the areas that will see this occultation.
The full Moon after next will be Tuesday night, September 17, at 10:35 PM EDT. This will be on Wednesday from Newfoundland and Greenland Time eastward across Eurasia, Africa, and Australia to the International Date Line. Most commercial calendars are based on Greenwich or Universal Time and will show this full Moon on Wednesday.
This will be a partial lunar eclipse. The Moon will start entering the partial shadow of the Earth at 8:41 PM EDT. The slight dimming of the Moon will be difficult to notice until the top edge of the Moon starts entering the full shadow at 10:13 PM. The peak of the eclipse will be at 10:44 PM with just the top 8.4% of the Moon in full shadow. The Moon will finish exiting the full shadow at 11:16 PM and the partial shadow on Wednesday morning at 12:47 AM.
This will also be the second of four consecutive supermoons. The Moon will appear full for about three days, from Monday evening through Thursday morning.
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