Astronomy and Stars
Discussions about astronomy and stars. As we look further out what can we find in the universe beyond Earth's atmosphere?
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A giant cosmic necklace glows brightly in this NASA Hubble Space Telescope image. The object, aptly named the Necklace Nebula, is a recently discovered planetary nebula, the glowing remains of an ordinary, Sun-like star. The nebula consists of a bright ring, measuring 12 trillion miles across, dotted with dense, bright knots of gas that resemble diamonds in a necklace. The knots glow brightly due to absorption of ultraviolet light from the central stars. The Necklace Nebula is located 15,000 light-years away in the constellation Sagitta (the Arrow). In this composite image, taken on July 2, 2011, Hubble's Wide Field Camera 3 captured the glow of hydrogen (blue), oxygen …
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These two images, taken about a week apart by NASA's Hubble Space Telescope, show four moons orbiting the distant, icy dwarf planet Pluto. The green circle in both snapshots marks the newly discovered moon, temporarily dubbed P4, found by Hubble in June. P4 is the smallest moon yet found around Pluto, with an estimated diameter of 8 to 21 miles (13 to 34 km). By comparison, Pluto's largest moon Charon is 746 miles (1,200 km) across. Nix and Hydra are 20 to 70 miles (32 to 113 km) wide. The new moon lies between the orbits of Nix and Hydra, two satellites discovered by Hubble in 2005. P4 completes an orbit around Pluto roughly every 31 days. The new moon was first seen i…
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These four images of Neptune were taken by NASA's Hubble Space Telescope during the planet's 16-hour rotation. The snapshots were taken at roughly four-hour intervals, offering a full view of the blue-green planet. Today marks Neptune's first orbit around the Sun since it was discovered nearly 165 years ago. These images were taken to commemorate the event. The Hubble images, taken with the Wide Field Camera 3 on June 25-26, reveal high-altitude clouds in the northern and southern hemispheres. The clouds are composed of methane ice crystals. In the Hubble images, absorption of red light by methane in Neptune's atmosphere gives the planet its distinctive aqua color. The …
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NASA's Hubble Space Telescope crossed another milestone in its 21-year space odyssey of exploration and discovery. On Monday, July 4, the Earth-orbiting observatory logged its one millionth science observation during a search for water in an exoplanet's atmosphere 1,000 light-years away. Although Hubble is best known for its stunning imagery of the cosmos, the millionth exposure is a spectroscopic measurement, where light is divided into its component colors. These color patterns can reveal the chemical composition of cosmic sources. This is an artist's concept of Hubble's millionth exposure, the extrasolar planet HAT-P-7b. It is a gas planet larger than Jupiter orbiting …
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A team of scientists studying the galaxy cluster Abell 2744, nicknamed Pandora's Cluster, have pieced together the cluster's complex and violent history using telescopes in space and on the ground, including the Hubble Space Telescope, the European Southern Observatory's Very Large Telescope, the Japanese Subaru telescope, and NASA's Chandra X-ray Observatory. The giant galaxy cluster appears to be the result of a simultaneous pile-up of at least four separate, smaller galaxy clusters that took place over a span of 350 million years. The galaxies in the cluster make up less than five percent of its mass. The gas (around 20 percent) is so hot that it shines only in X-ray…
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Resembling looming rain clouds on a stormy day, dark lanes of dust crisscross the giant elliptical galaxy Centaurus A. Hubble's panchromatic vision, stretching from ultraviolet through near-infrared wavelengths, reveals the vibrant glow of young, blue star clusters and a glimpse into regions normally obscured by the dust. This image was taken in July 2010 with Hubble's Wide Field Camera 3. View the full article
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Astronomers using NASA's Hubble Space Telescope are witnessing the unprecedented transition of a supernova to a supernova remnant, where light from an exploding star in a neighboring galaxy, the Large Magellanic Cloud, reached Earth in February 1987. Named Supernova 1987A, it was the closest supernova explosion witnessed in almost 400 years. The supernova's close proximity to Earth has allowed astronomers to study it in detail as it evolves. Now, the supernova debris, which has faded over the years, is brightening. This means that a different power source has begun to light the debris. The debris of SN 1987A is beginning to impact the surrounding ring, creating powerful s…
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Peering deep into the star-filled, ancient hub of our Milky Way (left), NASA's Hubble Space Telescope has found a rare class of oddball stars called blue stragglers. This is the first time such objects have been detected within our galaxy's bulge. Blue stragglers are so named because they seem to be lagging behind in their rate of aging compared with nearby older stars. The discovery is a spin-off from a seven-day-long survey conducted in 2006 called the Sagittarius Window Eclipsing Extrasolar Planet Search (SWEEPS). Hubble peered at and obtained variability information for 180,000 stars in the crowded central bulge of our galaxy, 26,000 light-years away. View th…
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Though the universe is filled with billions upon billions of stars, NASA's Hubble Space Telescope has been trained on a single variable star that in 1923 altered the course of modern astronomy. And, at least one famous astronomer of the time lamented that the discovery had shattered his world view. The star goes by the inauspicious name of Hubble variable number one, or V1, and resides two million light-years away in the outer regions of the neighboring Andromeda galaxy, or M31. V1 is a special class of pulsating star called a Cepheid variable that can be used to make reliable measurements of large cosmic distances. The star helped Edwin Hubble show that Andromeda lies be…
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The dwarf galaxy NGC 4214 is ablaze with young stars and gas clouds. Located around 10 million light-years away in the constellation of Canes Venatici (The Hunting Dogs), the galaxy's close proximity, combined with the wide variety of evolutionary stages among the stars, make it an ideal laboratory to research the triggers of star formation and evolution. This color image was taken using the Hubble Space Telescope's Wide Field Camera 3 in December 2009. View the full article
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Late last year, astronomers noticed an asteroid named Scheila had unexpectedly brightened, and it was sporting short-lived plumes. Data from NASA's Swift satellite and Hubble Space Telescope showed these changes likely occurred after Scheila was struck by a much smaller asteroid. This visible-light image of asteroid (596) Scheila was taken with Hubble's Wide Field Camera 3 on Dec. 27, 2010, when the asteroid was approximately 217 million miles away. The asteroid is surrounded by a C-shaped cloud, or coma, of dust particles. The asteroid body, which is approximately 70 miles across, appears star-like because it is overexposed so that the faint dust can be imaged. …
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To celebrate the 21st anniversary of the Hubble Space Telescope's deployment into space, astronomers at the Space Telescope Science Institute in Baltimore, Md., pointed Hubble's eye at an especially photogenic pair of interacting galaxies called Arp 273. The larger of the spiral galaxies, known as UGC 1810, has a disk that is distorted into a rose-like shape by the gravitational tidal pull of the companion galaxy below it, known as UGC 1813. This image is a composite of Hubble Wide Field Camera 3 data taken on December 17, 2010, with three separate filters that allow a broad range of wavelengths covering the ultraviolet, blue, and red portions of the spectrum. Hubble wa…
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Astronomers have uncovered one of the youngest galaxies in the distant universe, with stars that formed 13.5 billion years ago, a mere 200 million years after the Big Bang. The finding addresses questions about when the first galaxies arose, and how the early universe evolved. NASA's Hubble Space Telescope was the first to spot the newfound galaxy. Detailed observations from the W.M. Keck Observatory on Mauna Kea in Hawaii revealed the observed light dates to when the universe was only 950 million years old; the universe formed about 13.7 billion years ago. Infrared data from both Hubble and NASA's Spitzer Space Telescope revealed the galaxy's stars are quite mature, havi…
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NASA's Swift satellite, Hubble Space Telescope, and Chandra X-ray Observatory have teamed up to study one of the most puzzling cosmic blasts ever observed. More than a week later, high-energy radiation continues to brighten and fade from its location. Astronomers say they have never seen such a bright, variable, high-energy, long-lasting burst before. Usually, gamma-ray bursts mark the destruction of a massive star, and flaring emission from these events never lasts more than a few hours. On Monday, March 28, 2011, the Swift satellite's Burst Alert Telescope discovered the source in the constellation Draco when it erupted with the first in a series of powerful blasts. S…
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The Space Telescope Science Institute (STScI) announces today the selection of 17 new candidates for the Hubble Fellowship Program. This is one of the three prestigious postdoctoral fellowship programs funded by NASA. The other programs are the Sagan and the Einstein Fellowships. STScI administers the Hubble Fellowship Program for NASA. View the full article
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Astronomers using NASA's Hubble Space Telescope have ruled out an alternate theory on the nature of dark energy after recalculating the expansion rate of the universe to unprecedented accuracy. The universe appears to be expanding at an ever-increasing rate, and one explanation is that the universe is filled with a dark energy that works in the opposite way of gravity. One alternative to that hypothesis is that an enormous bubble of relatively empty space eight billion light-years across surrounds our galactic neighborhood. If we lived near the center of this void, observations of galaxies being pushed away from each other at accelerating speeds would be an illusion. This…
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Adam Riess, an astronomer at the Space Telescope Science Institute (STScI) and a professor in physics and astronomy at The Johns Hopkins University, today was awarded the 2011 Einstein Medal by the Albert Einstein Society, located in Bern, Switzerland. The Society recognized him for leadership in the High-z Supernova Search Team's 1998 discovery that the expansion rate of the universe is accelerating, a phenomenon widely attributed to a mysterious, unexplained "dark energy" filling the universe. Riess will receive the medal at a ceremony in Bern in May 2011. View the full article
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NASA's Hubble Space Telescope reveals a majestic disk of stars and dust lanes in this view of the spiral galaxy NGC 2841, which lies 46 million light-years away in the constellation of Ursa Major (The Great Bear). This image was taken in 2010 through four different filters on Hubble's Wide Field Camera 3. Wavelengths range from ultraviolet light through visible light to near-infrared light. View the full article
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How far is far? And, when do you know when you get there? This is not a Dr. Seuss riddle, but the ultimate "final frontier" confronting astronomers. We are on the cusp of seeing nearly as far as we ever can into the universe of stars and galaxies. The question can be better phrased: How young is young? And how do you know when you've seen the earliest objects that ever existed? That's because the farther we look into space the further back into time we see. We're accustomed to instantaneous communications on Earth, but starlight carries a roaming fee. It takes billions of years for information to reach us from the remote universe. Now astronomers have pushed the Hubble …
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These images by NASA's Hubble Space Telescope show off two dramatically different face-on views of the spiral galaxy M51, dubbed the Whirlpool Galaxy. The image at left, taken in visible light, highlights the attributes of a typical spiral galaxy, including graceful, curving arms, pink star-forming regions, and brilliant blue strands of star clusters. In the image at right, most of the starlight has been removed, revealing the Whirlpool's skeletal dust structure, as seen in near-infrared light. This new image is the sharpest view of the dense dust in M51. The narrow lanes of dust revealed by Hubble reflect the galaxy's moniker, the Whirlpool Galaxy, as if they were swir…
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Astronomers are finding that the idiom "can't see the forest for the trees" applies to the universe of galaxies as well. In a paper published today in the science journal Nature, an international team of astronomers predicts that foreground galaxies will affect images of extremely far galaxies. The gravitational fields of the foreground galaxies distort space like a funhouse mirror. This means that a significant fraction of far background galaxies will appear on the sky near foreground galaxies. The good news is that the remote galaxies will appear brighter because of a phenomenon called gravitational lensing. This will need to be factored in when astronomers plan to look…
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A ghostly, glowing, green blob of gas has become one of astronomy's great cosmic mystery stories. The space oddity was spied in 2007 by Dutch high-school teacher Hanny van Arkel while participating in the online Galaxy Zoo project. The cosmic blob, called Hanny's Voorwerp (Hanny's Object in Dutch), appears to be a solitary green island floating near a normal-looking spiral galaxy, called IC 2497. Since the discovery, puzzled astronomers have used a slew of telescopes, including X-ray and radio observatories, to help unwrap the mystery. Astronomers found that Hanny's Voorwerp is the only visible part of a 300-light-year-long gaseous streamer stretching around the galaxy. T…
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A survey of more than 200,000 stars in our Milky Way galaxy has unveiled the sometimes petulant behavior of tiny dwarf stars. These stars, which are smaller than the Sun, can unleash powerful eruptions called flares that may release the energy of more than 100 million atomic bombs. Red dwarfs are the most abundant stars in our universe and are presumably hosts to numerous planets. However, their erratic behavior could make life unpleasant, if not impossible, for many alien worlds. The flares the stars unleash would blast any planets orbiting them with ultraviolet light, bursts of X-rays, and a gush of charged particles called a stellar wind. Studying the light from 215,…
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A delicate sphere of gas, photographed by NASA's Hubble Space Telescope, floats serenely in the depths of space. The pristine shell, or bubble, is the result of gas that is being shocked by the expanding blast wave from a supernova. Called SNR 0509-67.5 (or SNR 0509 for short), the bubble is the visible remnant of a powerful stellar explosion in the Large Magellanic Cloud (LMC), a small galaxy about 160,000 light-years from Earth. Ripples in the shell's surface may be caused by either subtle variations in the density of the ambient interstellar gas, or possibly driven from the interior by pieces of the ejecta. The bubble-shaped shroud of gas is 23 light-years across and i…
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Elliptical galaxies were once thought to be aging star cities whose star-making heyday was billions of years ago. But new observations with NASA's Hubble Space Telescope are helping to show that elliptical galaxies still have some youthful vigor left, thanks to encounters with smaller galaxies. Images of the core of NGC 4150, taken in near-ultraviolet light with the sharp-eyed Wide Field Camera 3 (WFC3), reveal streamers of dust and gas and clumps of young, blue stars that are significantly less than a billion years old. Evidence shows that the star birth was sparked by a merger with a dwarf galaxy. The new study helps bolster the emerging view that most elliptical gala…
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