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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The Space Telescope Science Institute (STScI) has selected fifteen young scientists for the 1997 Hubble Postdoctoral Fellowship Program. The awardees were selected from a pool of applications received from highly qualified candidates worldwide. View the full article
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The Hubble telescope is back at work, capturing this view of the butterfly-wing-shaped nebula, NGC 2346. The nebula is about 2,000 light-years away from Earth in the direction of the constellation Monoceros. It represents the spectacular "last gasp" of a double-star system at the nebula's center. The image was taken March 6, 1997 as part of the re-commissioning of Hubble's previously installed scientific instruments following a successful servicing mission. View the full article
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This Hubble telescope snapshot unveils a pair of one-half, light-year-long interstellar "twisters" – eerie funnels and twisted-rope structures [upper left] – in the heart of the Lagoon Nebula (M8) which lies 5,000 light-years from Earth in the direction of the constellation Sagittarius. The hot, central star, O Herschel 36 [upper left], is the primary source of the illuminating light for the brightest region in the nebula, called the Hourglass. The glare from this hot star is eroding the clouds by heating the hydrogen gas in them [seen as a blue "mist" at the right of the image]. This activity drives away violent stellar winds that are tearing into the cool clouds. …
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The Hubble telescope has found a long-sought population of "stellar outcasts" ? stars tossed out of their home galaxies into the dark emptiness of intergalactic space. This is the first time stars have been found more than 300,000 light-years (three Milky Way diameters) from the nearest big galaxy. The isolated stars dwell in the Virgo cluster of galaxies, about 60 million light-years from Earth. The results suggest this population of "lone stars" accounts for 10 percent of the Virgo cluster's mass, or 1 trillion Sun-like stars adrift among the 2,500 galaxies in Virgo. This is an illustration of the view of the nighttime sky from the surface of a hypothetical planet orb…
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Though the brightest supernova in four centuries lit up the southern sky almost exactly 10 years ago on Feb. 23, 1987, astronomers have waited a decade for the ballooning fireball to become large enough ? about one-sixth of a light-year ? to be resolved from Earth's orbit with the Hubble telescope. Hubble's sharp "eyes" have resolved a dumbbell-shaped structure ? one-tenth of a light-year long ? that consists of two blobs of debris expanding apart at nearly 6 million mph from each other. This Hubble picture shows the supernova, designated 1987A, and its neighborhood. The four frames follow the evolution of the supernova debris. View the full article
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Announcing the discovery of three black holes in three normal galaxies, astronomers suggest that nearly all galaxies may harbor super-massive black holes that once powered quasars (extremely luminous objects in the centers of galaxies), but are now quiescent. This conclusion is based on a census of 27 nearby galaxies carried out by the Hubble telescope and ground-based observatories in Hawaii. The three galaxies in these images are believed to contain central, super-massive black holes. The galaxy NGC 4486B [lower left] shows a double nucleus [lower right]. The picture at lower right is a close-up of the central region of NGC 4486B. View the full article
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Analyzing the pictures of some of the most distant galaxies in the universe, astronomers are uncovering intriguing new evidence that the Big Bang was followed by a stellar "baby boom." Hubble's unprecedented measurement of the rate of star birth in remote galaxies, which existed when the cosmos was less than 10 percent its current age, supports the emerging view that the early universe had an active, dynamic youth where stars formed out of dust and gas at a ferocious rate. The graph is based on observations of distant galaxies made by the Hubble telescope and ground-based observatories. Hubble shows a steep rise in star birth that happened shortly after the Big Bang. Th…
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This is the first direct image of a star other than the Sun. Called Alpha Orionis, or Betelgeuse, the star is a red super giant, a Sun-like star nearing the end of its life. The Hubble picture reveals a huge ultraviolet atmosphere with a mysterious hot spot on the stellar behemoth's surface. The enormous bright spot, twice the diameter of the Earth's orbit, is at least 2,000 degrees Kelvin hotter than the star's surface. View the full article
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Analysis of dramatic Hubble telescope images reveals immense comet-shaped knots of gas in the heart of the Cartwheel Galaxy. The galaxy's unusual wagon-wheel shape was created by a nearly head-on collision with a smaller galaxy about 200 million years ago. The discovery of the knots may eventually help answer some compelling questions, such as why the center of the Cartwheel has little star formation and what causes the unusual spoke-shaped pattern between the bright outer ring of young stars and the mysterious, dusty galactic center. The galaxy's center is the bright object in the center of the left-hand picture; the spoke-like structures are wisps of material connecti…
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Dramatic Hubble telescope pictures reveal that quasars live in a remarkable assortment of galaxies, many of which are violently colliding. This complicated picture suggests there may be a variety of mechanisms – some quite subtle – for "turning on" quasars, the universe's most energetic objects. When seen through ground-based telescopes, these compact, enigmatic light sources resemble stars, yet they are billions of light-years away and several hundred billion times brighter than normal stars. The following Hubble snapshots offer examples of quasar home sites. Astronomers believe that a quasar turns on when a massive black hole at the center of a galaxy feeds on gas and…
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Two Hubble telescope images of Mars, taken about a month apart, reveal a state-sized dust storm churning near the edge of the northern polar cap. The polar storm is probably a consequence of large temperature differences between the polar ice and the dark regions to the south, which are heated by the springtime sun. The increased sunlight also causes the dry ice in the polar cap to shrink. Mars is famous for large, planet-wide dust storms. This is the first time that such an event has been caught near the receding northern polar cap. In the top picture, the salmon-colored notch in the white northern polar cap is a 600-mile-long (1,000 kilometer-long) storm – nearly the …
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The Hubble telescope has been used to assemble a time-lapse color movie showing a full 16-hour rotation of the distant planet Neptune. The movie, made from a series of Hubble observations over nine consecutive orbits, allows astronomers to track cloud motion on the planet. The clear pictures reveal the planet's powerful equatorial jet stream, immense storms, and dark spot in the Northern Hemisphere. These snapshots provide views of the weather on opposite hemispheres. The photos disclose features of Neptune's blustery weather. View the full article
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The Hubble telescope's sharp view of the rapid, spectacular dance of luminescent gases high in Jupiter's atmosphere – better known as aurora – is allowing astronomers to map Jupiter's immense magnetic field and better understand how it generates such phenomena. The ultraviolet-light images [bottom frames] show how the auroral emissions change in brightness and shape as Jupiter rotates. The aurorae are the bright, circular features at the top and bottom of the planet. The top panel illustrates the effects of emissions from Io, one of Jupiter's moons. Io ejects an invisible electrical current of charged particles, which flow along the planet's magnetic field lines. …
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Clusters of stars and a fishhook-shaped cloud of luminescent gases glow brilliantly in NGC 2363, a giant star-forming region in the Magellanic galaxy NGC 2366. The brightest object visible in the Hubble telescope image [right] is a member of a rare class of stars called an erupting Luminous Blue Variable [at the tip of the fishhook]. This monstrous star (30 to 60 times as massive as the Sun) is in a very unstable, eruptive phase of its life. The Hubble telescope photo is the only one in which the star can be clearly isolated from the rest of the cluster. A view of this region from a terrestrial telescope is on the left. Only four giant eruptions of these special stars h…
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This image shows Jupiter's volcanic moon Io passing above the turbulent clouds of the giant planet. The conspicuous black spot on Jupiter is Io's shadow. This shadow is about the size of Io (2,262 miles or 3,640 kilometers across) and sweeps across the face of Jupiter at 38,000 mph (17 kilometers per second). The smallest details seen on Io and Jupiter are about 100 miles across. Bright patches visible on Io are regions of sulfur dioxide frost. Io is roughly the size of Earth's moon but 2,000 times farther away. View the full article
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New Hubble telescope images unveil what may be galaxies under construction in the early universe. Hubble's detailed pictures reveal a grouping of 18 gigantic star clusters that appear to be the same distance from Earth, and close enough to each other that they will eventually merge into a few galaxy- sized objects. They are so far away, 11 billion light-years, that they existed during the epoch when it is commonly believed galaxies started to form. These results add weight to a leading theory that galaxies grew by starting out as clumps of stars, which, through a complex series of encounters, consolidated into larger assemblages that we see as fully formed galaxies. …
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The colorful picture on the right is a Hubble telescope snapshot of a vast nebula of dust and gas called NGC 604, which lies in the neighboring spiral galaxy M33. This region, located in the galaxy's spiral arm, is fertile ground for star birth. Though such nebulae are common in galaxies, this one is particularly large, nearly 1,500 light-years across. The image on the left, taken by a ground-based telescope, illustrates the vastness of this nebula. The galaxy resides 2.7 million light-years from Earth in the constellation Triangulum. View the full article
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The Hubble telescope reached a milestone several years sooner than scientists expected when it snapped its 100,000th exposure June 22, 1996. The six-year-old orbiting observatory has averaged 1,389 exposures a month, an amount that would make any photographer envious. This black-and-white picture represents the telescope's 100,000th exposure: a quasar that resides about 9 billion light-years from Earth. The quasar is the bright object in the center of the photo. The fainter object just above it is an elliptical galaxy. Although the two objects appear to be close together, they are actually separated by about 2 billion light-years. View the full article
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The Hubble telescope has been used successfully to measure the diameters of a special class of pulsating star called a Mira variable, which rhythmically change size. The results suggest these gigantic, old stars aren't round but egg-shaped. Knowing more about these enigmatic stars is crucial to understanding how stars evolve, and may preview the fate of our Sun, five billion years from now. Due to their distance, the stars are too small for their disks to be resolved in conventional visible-light pictures, so astronomers used Hubble's Fine Guidance Sensors to measure the widths of two Mira variables, R Leonis and W. Hydrae. View the full article
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Astronomers analyzing the Hubble Deep Field - the faintest view of the universe taken with the Hubble telescope - may have identified what may prove to be the most distant objects observed to date. Scattered among the nearly 2,000 galaxies in the Hubble images, which were taken in December 1995, researchers have found several dozen galaxies they believe exhibit characteristics which make them appear to be more distant than any seen previously. Six of the galaxies appear to be more distant than the farthest quasars, the current distance record holders. The arrow pinpoints one of those six galaxies. View the full article
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A huge, billowing pair of gas and dust clouds is captured in this stunning Hubble telescope picture of the super-massive star Eta Carinae. Even though Eta Carinae is more than 8,000 light-years away, features 10 billion miles across (about the diameter of our solar system) can be distinguished. Eta Carinae suffered a giant outburst about 150 years ago, when it became one of the brightest stars in the southern sky. Though the star released as much visible light as a supernova explosion, it survived the outburst. Somehow, the explosion produced two lobes and a large, thin equatorial disk, all moving outward at about 1.5 million miles per hour. Estimated to be 100 times he…
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Probing the mysterious heart of the Crab Nebula, the tattered remains of an exploding star, astronomers have found this object to be even more dynamic than previously understood. These findings are based on a cosmic "movie" assembled from a series of Hubble telescope observations. The sequence of pictures is giving astronomers a remarkable look at the dynamic relationship between the tiny Crab pulsar - the collapsed core of the exploding star - and the vast nebula of dust and gas that it powers. This picture, which reveals the inner parts of the Crab, represents one frame from the movie. The Crab pulsar is the star on the left [white dot] near the center of the frame. S…
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Using the Hubble telescope, two international teams of astronomers are reporting major progress in converging on an accurate measurement of the universe's rate of expansion - a value that has been debated for over half a century. These new results yield ranges for the age of the universe from 9-12 billion years and 11-14 billion years, respectively. The black and white photograph from a ground-based telescope shows the entire galaxy. The color image from the Hubble telescope shows a region in NGC 1365, a barred spiral galaxy located in a cluster of galaxies called Fornax. A barred spiral galaxy is characterized by a "bar" of stars, dust, and gas across its center. Astro…
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The Space Telescope Science Institute (STScI) and the Astronomical Society of the Pacific (ASP) are pleased to announce the availability of RealSky CD, the digitized Palomar Observatory Sky Survey compressed by a factor of 100x, available on 8 CD-ROMs. View the full article
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This is a rare view of Saturn's rings seen just after the Sun has set below the ring plane. This perspective is unusual because the Earth is slightly above Saturn's rings and the Sun is below them. Normally we see the rings fully illuminated by the Sun. The Hubble telescope photograph reveals three bright ring features [moving from the outer to the inner rings]: the F Ring, the Cassini Division, and the C Ring. The low concentration of material in these rings allows light from the Sun to shine through them. The A and B rings are much denser, which limits the amount of light that penetrates through them. Instead, they are faintly visible because they reflect light from S…
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