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Week in images: 17 - 21 May 2021
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By NASA
Skywatching Skywatching Home What’s Up What to See Tonight Meteor Showers Eclipses Moon Guide More Tips & Guides Skywatching FAQ Night Sky Network Eta Aquarids & Waiting for a Nova!
The first week of May brings the annual Eta Aquarid meteors, peaking on the 6th. And sometime in the next few months, astronomers predict a “new star” or nova explosion will become visible to the unaided eye.
Skywatching Highlights
All Month – Planet Visibility:
Venus: Appears very bright and low in the east in the hour before sunrise all month. Mars: Easy to find in the west in the first few hours of the night, all month long. Sets around midnight to 1 a.m. local time. Jupiter: Shines brightly in the west following sunset all month. Early in the month it sets about two hours after the Sun, but by late May it’s setting only an hour after sunset. Saturn: Begins the month next to Venus, low in the eastern sky before sunrise. Quickly separates from Saturn and rises higher in the sky each day before dawn. Daily Highlights
May 6 – Eta Aquarid Meteors – The peak of this annual shower is early on the morning of May 6th. The two or three nights before that are also decent opportunities to spy a few shooting stars. On the peak night this year, the Moon sets by around 3 a.m., leaving dark skies until dawn, for ideal viewing conditions. Seeing 10-20 meteors per hour is common for the Northern Hemisphere, while south of the equator, observers tend to see substantially more.
May 3 – Mars & Moon: The first quarter Moon appears right next to the Red Planet on the 3rd. Find them in the west during the first half of the night that evening.
All month – Venus & Saturn: Low in the eastern sky each morning you’ll find bright Venus paired with much fainter Saturn. They start the month close together, but Saturn pulls away and rises higher over the course of the month.
All month – Mars & Jupiter: The planets to look for on May evenings are Mars and Jupiter. They’re visible for a couple of hours after sunset in the western sky.
All month – Corona Borealis: Practice finding this constellation in the eastern part of the sky during the first half of the night, so you have a point of comparison when the T CrB nova appears there, likely in the next few months.
Transcript
What’s Up for May? Four bright planets, morning and night, a chance of meteor showers, and waiting for a nova.
May Planet Viewing
For planet watching this month, you’ll find Mars and Jupiter in the west following sunset. Mars sticks around for several hours after it gets dark out, but Jupiter is setting by 9:30 or 10 p.m., and getting lower in the sky each day. The first quarter Moon appears right next to the Red Planet on the 3rd. Find them in the west during the first half of the night that evening.
Sky chart showing Venus and Saturn with the crescent Moon in the predawn sky on May 23., 2025. NASA/JPL-Caltech In the morning sky, Venus and Saturn are the planets to look for in May. They begin the month appearing close together on the sky, and progressively pull farther apart as the month goes on. For several days in late May, early risers will enjoy a gathering of the Moon with Saturn and Venus in the eastern sky before dawn. Watch as the Moon passes the two planets while becoming an increasingly slimmer crescent. You’ll find the Moon hanging between Venus and Saturn on the 23rd.
Eta Aquarid Meteor Shower
Early May brings the annual Eta Aquarid meteor shower. These are meteors that originate from Comet Halley. Earth passes through the comet’s dust stream each May, and again in October. Eta Aquarids are fast moving, and a lot of them produce persistent dust trains that linger for seconds after the meteor’s initial streak.
This is one of the best annual showers in the Southern Hemisphere, but tends to be more subdued North of the Equator, where we typically see 10-20 meteors per hour. On the peak night this year, the Moon sets by around 3 a.m., leaving dark skies until dawn, for ideal viewing conditions. While the peak is early on the morning of May 6th, the two or three nights before that are also decent opportunities to spy a few shooting stars.
Waiting for a Nova
Sky chart showing constellation Corona Borealis with the location where nova “T CrB” is predicted to appear. The view depicts the constellation with the nova occurring, indicated by an arrow. NASA/JPL-Caltech Astronomers have been waiting expectantly for light from a distant explosion to reach us here on Earth. An event called a nova is anticipated to occur sometime in the coming months. Some 3,000 light years away is a binary star system called T Coronae Borealis, or “T CrB.” It consists of a red giant star with a smaller white dwarf star orbiting closely around it. Now the giant’s outer atmosphere is all puffed up, and the dwarf star is close enough that its gravity continually captures some of the giant’s hydrogen. About every 80 years, the white dwarf has accumulated so much of the other star’s hydrogen, that it ignites a thermonuclear explosion. And that’s the nova.
T Coronae Borealis is located in the constellation Corona Borealis, or the “Northern Crown,” and it’s normally far too faint to see with the unaided eye. But it’s predicted the nova will be as bright as the constellation’s brightest star, which is about as bright as the North Star, Polaris. You’ll find Corona Borealis right in between the two bright stars Arcturus and Vega, and you can use the Big Dipper’s handle to point you to the right part of the sky. Try having a look for it on clear, dark nights before the nova, so you’ll have a comparison when a new star suddenly becomes visible there.
A sky chart indicating how to locate the constellation Corona Borealis between the bright stars Arcturus and Vega. The Big Dipper’s handle points in the direction of Corona Borealis. NASA/JPL-Caltech Now, you may have heard about this months ago, as astronomers started keeping watch for the nova midway through 2024, but it hasn’t happened yet. Predicting exactly when novas or any sort of stellar outburst will happen is tricky, but excitement began growing when astronomers observed the star to dim suddenly, much as it did right before its previous nova in 1946. When the nova finally does occur, it won’t stay bright for long, likely flaring in peak brightness for only a few days. And since it’s not predicted again for another 80 years, you might just want to join the watch for this super rare, naked eye stellar explosion in the sky!
Here are the phases of the Moon for May.
The phases of the Moon for May 2025. NASA/JPL-Caltech You can stay up to date on all of NASA’s missions exploring the solar system and beyond at NASA Science.
I’m Preston Dyches from NASA’s Jet Propulsion Laboratory, and that’s What’s Up for this month.
Keep Exploring Discover More Topics From NASA
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By NASA
4 min read
May’s Night Sky Notes: How Do We Find Exoplanets?
Astronomers have been trying to discover evidence that worlds exist around stars other than our Sun since the 19th century. By the mid-1990s, technology finally caught up with the desire for discovery and led to the first discovery of a planet orbiting another sun-like star, Pegasi 51b. Why did it take so long to discover these distant worlds, and what techniques do astronomers use to find them?
The Transit Method
A planet passing in front of its parent star creates a drop in the star’s apparent brightness, called a transit. Exoplanet Watch participants can look for transits in data from ground-based telescopes, helping scientists refine measurements of the length of a planet’s orbit around its star. Credit: NASA’s Ames Research Center One of the most famous exoplanet detection methods is the transit method, used by Kepler and other observatories. When a planet crosses in front of its host star, the light from the star dips slightly in brightness. Scientists can confirm a planet orbits its host star by repeatedly detecting these incredibly tiny dips in brightness using sensitive instruments. If you can imagine trying to detect the dip in light from a massive searchlight when an ant crosses in front of it, at a distance of tens of miles away, you can begin to see how difficult it can be to spot a planet from light-years away! Another drawback to the transit method is that the distant solar system must be at a favorable angle to our point of view here on Earth – if the distant system’s angle is just slightly askew, there will be no transits. Even in our solar system, a transit is very rare. For example, there were two transits of Venus visible across our Sun from Earth in this century. But the next time Venus transits the Sun as seen from Earth will be in the year 2117 – more than a century from the 2012 transit, even though Venus will have completed nearly 150 orbits around the Sun by then!
The Wobble Method
As a planet orbits a star, the star wobbles. This causes a change in the appearance of the star’s spectrum called Doppler shift. Because the change in wavelength is directly related to relative speed, astronomers can use Doppler shift to calculate exactly how fast an object is moving toward or away from us. Astronomers can also track the Doppler shift of a star over time to estimate the mass of the planet orbiting it. NASA, ESA, CSA, Leah Hustak (STScI) Spotting the Doppler shift of a star’s spectra was used to find Pegasi 51b, the first planet detected around a Sun-like star. This technique is called the radial velocity or “wobble” method. Astronomers split up the visible light emitted by a star into a rainbow. These spectra, and gaps between the normally smooth bands of light, help determine the elements that make up the star. However, if there is a planet orbiting the star, it causes the star to wobble ever so slightly back and forth. This will, in turn, cause the lines within the spectra to shift ever so slightly towards the blue and red ends of the spectrum as the star wobbles slightly away and towards us. This is caused by the blue and red shifts of the star’s light. By carefully measuring the amount of shift in the star’s spectra, astronomers can determine the size of the object pulling on the host star and if the companion is indeed a planet. By tracking the variation in this periodic shift of the spectra, they can also determine the time it takes the planet to orbit its parent star.
Direct Imaging
Finally, exoplanets can be revealed by directly imaging them, such as this image of four planets found orbiting the star HR 8799! Space telescopes use instruments called coronagraphs to block the bright light from the host star and capture the dim light from planets. The Hubble Space Telescope has captured images of giant planets orbiting a few nearby systems, and the James Webb Space Telescope has only improved on these observations by uncovering more details, such as the colors and spectra of exoplanet atmospheres, temperatures, detecting potential exomoons, and even scanning atmospheres for potential biosignatures!
NASA’s James Webb Space Telescope has provided the clearest look in the infrared yet at the iconic multi-planet system HR 8799. The closest planet to the star, HR 8799 e, orbits 1.5 billion miles from its star, which in our solar system would be located between the orbit of Saturn and Neptune. The furthest, HR 8799 b, orbits around 6.3 billion miles from the star, more than twice Neptune’s orbital distance. Colors are applied to filters from Webb’s NIRCam (Near-Infrared Camera), revealing their intrinsic differences. A star symbol marks the location of the host star HR 8799, whose light has been blocked by the coronagraph. In this image, the color blue is assigned to 4.1 micron light, green to 4.3 micron light, and red to the 4.6 micron light. NASA, ESA, CSA, STScI, W. Balmer (JHU), L. Pueyo (STScI), M. Perrin (STScI) You can find more information and activities on NASA’s Exoplanets page, such as the Eyes on Exoplanets browser-based program, The Exoplaneteers, and some of the latest exoplanet news. Lastly, you can find more resources in our News & Resources section, including a clever demo on how astronomers use the wobble method to detect planets!
The future of exoplanet discovery is only just beginning, promising rich rewards in humanity’s understanding of our place in the Universe, where we are from, and if there is life elsewhere in our cosmos.
Originally posted by Dave Prosper: July 2015
Last Updated by Kat Troche: April 2025
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By European Space Agency
Week in images: 21-25 April 2025
Discover our week through the lens
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By NASA
The asteroid Donaldjohanson as seen by the Lucy Long-Range Reconnaissance Imager (L’LORRI). This is one of the most detailed images returned by NASA’s Lucy spacecraft during its flyby. This image was taken at 1:51 p.m. EDT (17:51 UTC), April 20, 2025, near closest approach, from a range of approximately 660 miles (1,100 km). The spacecraft’s closest approach distance was 600 miles (960 km), but the image shown was taken approximately 40 seconds beforehand. The image has been sharpened and processed to enhance contrast.NASA/Goddard/SwRI/Johns Hopkins APL/NOIRLab NASA’s Lucy spacecraft took this image of the main belt asteroid Donaldjohanson during its flyby on April 20, 2025, showing the elongated contact binary (an object formed when two smaller bodies collide). This was Lucy’s second flyby in the spacecraft’s 12-year mission.
Launched on Oct. 16, 2021, Lucy is the first space mission sent to explore a diverse population of small bodies known as the Jupiter Trojan asteroids. These remnants of our early solar system are trapped on stable orbits associated with – but not close to – the giant planet Jupiter. Lucy will explore a record-breaking number of asteroids, flying by three asteroids in the solar system’s main asteroid belt, and by eight Trojan asteroids that share an orbit around the Sun with Jupiter. April 20, 2025 marked Lucy’s second flyby. The spacecraft’s next target is Trojan asteroid Eurybates and its satellite Queta in Aug. 2027.
Lucy is named for a fossilized skeleton of a prehuman ancestor. This flyby marked the first time NASA sent a spacecraft to a planetary body named after a living person. Asteroid Donaldjohanson was unnamed before becoming a target. The name Donaldjohanson was chosen in honor of the paleoanthropologist who discovered the Lucy fossil, Dr. Donald Johanson.
Learn more about Lucy’s flyby of asteroid Donaldjohanson.
Image credit: NASA/Goddard/SwRI/Johns Hopkins APL/NOIRLab
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By NASA
2 min read
First Results from the Eclipse Soundscapes Project: Webinar on May 7
How do the sudden darkness and temperature changes of a solar eclipse impact life on Earth? The Eclipse Soundscapes project invited you to document changes in the environment during the week of the April 8, 2024 total solar eclipse, using your own senses or an audiomoth sound recorder.
Thanks to your participation, the Eclipse Soundscapes team collected 25 terabytes of audio data during the 2023 and 2024 solar eclipses. “It was really empowering for me to participate in a scientific research study with my son beside me so he could see how scientific data can be (collected),” said one Eclipse Soundscapes volunteer.
More than 500 volunteers collected data using AudioMoth recorders during the April 8, 2024 eclipse for the Eclipse Soundscapes project. Credit: Eclipse Soundscapes Since the eclipse, the Eclipse Soundscapes team has been turning the submitted data into a new, carefully validated data set. They have been assessing recording quality, verifying timestamps, and logging other kinds of information that support the submitted data. With the newly validated data, they are now using machine learning to study wildlife behavior and compare regional differences. They do some of this work using spectrographic analysis—spreading out the sound into different frequency ranges like a prism spreads light into a rainbow. The team is also working to make the validated data freely available to the public on the Zenodo website—a free, open-source research data repository developed by CERN (the European Organization for Nuclear Research) that allows researchers to share and preserve their work, regardless of discipline or format.
The team’s first inspection of the data suggests that some species may mimic dusk-like behavior during totality. Want to hear more early results? You can join the team’s live webinar on May 7, 2025, at 2:00 p.m. EST with Dr. Brent Pease. Register now at EclipseSoundscapes.org. You can also explore this interactive map of data analysis sites, with details about each site, including partner organizations.
Register for the May 7 Preliminary Results WEBINAR
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