Astronomy Picture of the Day Search Results for "perseus"

APOD: 2009 February 14 - IC 1805: The Heart Nebula
Explanation: Sprawling across almost 200 light-years, emission nebula IC 1805 is a mix of glowing interstellar gas and dark dust clouds. Derived from its Valentine's-Day-approved shape, its nickname is the Heart Nebula. About 7,500 light-years away in the Perseus spiral arm of our galaxy, stars were born in IC 1805. In fact, near the cosmic heart's center are the massive hot stars of a newborn star cluster also known as Melotte 15, about 1.5 million years young. A little ironically, the Heart Nebula is located in the constellation Cassiopeia. From Greek mythology, the northern constellation is named for a vain and boastful queen. This deep view of the region around the Heart Nebula, cropped from a larger mosaic, spans about 2.5 degrees on the sky or about 5 times the diameter of the Full Moon.

APOD: 2009 February 12 - Zodiacal Light Vs. Milky Way
Explanation: Two fundamental planes of planet Earth's sky compete for attention in this remarkable wide-angle vista, recorded on January 23rd. Arcing above the horizon and into the night at the left is a beautiful band of Zodiacal Light - sunlight scattered by dust in the solar system's ecliptic plane. Its opponent on the right is composed of the faint stars, dust clouds, and nebulae along the plane of our Milky Way Galaxy. Both celestial bands stand above the domes and towers of the Teide Observatory on the island of Tenerife. Also out to play in the pristine, dark skies over the Canary Islands, are brilliant Venus (lower left), the distant Andromeda Galaxy (near center), and the lovely Pleiades star cluster (top center). Of course, seasoned skygazers might even spot M33, the California Nebula, IC1805, and the double star cluster of Perseus. (Need some help? Just slide your cursor over the picture.)

APOD: 2009 January 30 - NGC 1579: Trifid of the North
Explanation: Colorful NGC 1579 resembles the better known Trifid Nebula, but lies much farther north in planet Earth's sky, in the heroic constellation Perseus. About 2,100 light-years away and 3 light-years across, NGC 1579 is, like the Trifid, a study in contrasting blue and red colors, with dark dust lanes prominent in the nebula's central regions. In both, dust reflects starlight to produce beautiful blue reflection nebulae. But unlike the Trifid, in NGC 1579 the reddish glow is not emission from clouds of glowing hydrogen gas excited by ultraviolet light from a nearby hot star. Instead, the dust in NGC 1579 drastically diminishes, reddens, and scatters the light from an embedded, extremely young, massive star, itself a strong emitter of the characteristic red hydrogen alpha light.

APOD: 2009 January 3 - Double Cluster in Perseus
Explanation: Some 7,000 light-years away, this pair of open or galactic star clusters is an easy binocular target, a lovely starfield in the northern constellation Perseus. Also visible to the unaided eye from dark sky areas, it was cataloged in 130 BC by Greek astronomer Hipparchus. Now known as h and chi Persei, or NGC 869(above right) and NGC 884, the clusters themselves are separated by only a few hundred light-years and contain stars much younger and hotter than the Sun. In addition to being physically close together, the clusters' ages based on their individual stars are similar - evidence that both clusters were likely a product of the same star-forming region.

APOD: 2008 November 21 - M76 Above and Below
Explanation: Also known by the popular name the "Little Dumbbell Nebula", M76 is one of the fainter objects listed in Charles Messier's 18th century Catalog of Nebulae and Star Clusters. Like its better-known namesake M27 (the Dumbbell Nebula), M76 is recognized as a planetary nebula - a gaseous shroud cast off by a dying sunlike star. The nebula itself is thought to be shaped more like a donut, its central box-like appearance due to our nearly edge-on view. Gas expanding more rapidly away from the donut hole produces the more extensive, far flung material in this remarkable image that uses narrow-band filters to highlight the emission from hydrogen (in red) and oxygen atoms (in greenish blue). In particular, complex oxygen emission features are seen above and below the main nebula to a degree not detected in most images of M76. Distance estimates place M76 about 3 to 5 thousand light-years away toward the heroic constellation Perseus, making the nebula over a light-year in diameter.

APOD: 2008 October 24 - Amazing Comet Holmes
Explanation: One year ago, Comet 17P/Holmes amazed sky watchers across planet Earth. A stunningly rapid outburst transformed it from a faint comet quietly orbiting the Sun with a period of about 7 years to a naked-eye comet rivaling the brighter stars in the constellation Perseus. Its largely tail-less shape, as in this wide-angle view recorded on November 11, 2007, became well-known to astronomers trying to unravel the mystery of the comet's surprising outburst . Still, Comet Holmes had a dim ion tail that was seen to separate from the bright coma. In this image, the separated tail creates the illusion of a reflection nebula. It appears as a faint bluish haze right of center against a background of stars in the loosely grouped Alpha Persei Moving Cluster.

APOD: 2008 September 26 - Moon Rays over Byurakan Observatory
Explanation: On September 7th, the first quarter Moon and passing clouds contributed to a dramatic night sky over the Byurakan Astrophysical Observatory. This panoramic view begins at the left looking toward the eastern horizon and the rising stars of the constellation Perseus. Sweeping your gaze to the right (south), you'll find the large observatory dome, housing a 2.6 meter diameter telescope, backlit by lights from nearby Yerevan, capital city of Armenia. Fittingly poised above the observatory dome is the bright, giant star Enif in the high-flying constellation Pegasus. Farther to the right, the brightest celestial beacon just above the clouds is our Solar System's ruling gas giant Jupiter. At the far right, the Moon is nearly hidden by an approaching cloudbank, but the clouds themselves actually cast shadows in the bright moonlight, creating the effect of Moon rays across the evening sky.

APOD: 2008 September 11 - Mountain Top Meteors
Explanation: A mountain top above the clouds and light-polluted cities was a good place to go to watch this August's Perseid meteor shower. In fact, this composite picture from one of the highest points in Romania, the Omu summit (2,507 meters) in the Southern Carpathian Mountains, captures about 20 of the shower's bright streaks against a starry night sky. The cosmic debris stream that creates the shower is composed of dust particles moving along parallel paths, following the orbit of their parent comet Swift-Tuttle. Looking toward the shower's radiant point in the constellation Perseus, perspective causes the parallel meteor streaks to appear to diverge. But looking directly away from the radiant point, as in this view, perspective actually makes the Perseid meteors seem to be converging toward a point below the horizon.

APOD: 2008 August 22 - Active Galaxy NGC 1275
Explanation: Active galaxy NGC 1275 is the central, dominant member of the large and relatively nearby Perseus Cluster of Galaxies. A prodigious source of x-rays and radio emission, NGC 1275 accretes matter as entire galaxies fall into it, ultimately feeding a supermassive black hole at the galaxy's core. This stunning visible light image from the Hubble Space Telescope shows galactic debris and filaments of glowing gas, some up to 20,000 light-years long. The filaments persist in NGC 1275, even though the turmoil of galactic collisions should destroy them. What keeps the filaments together? Recent work indicates that the structures, pushed out from the galaxy's center by the black hole's activity, are held together by magnetic fields. To add x-ray data from the Chandra Observatory and radio data from the Very Large Array to the Hubble image, just slide your cursor over the picture. In the resulting composite, x-rays highlight the shells of hot gas surrounding the center of the galaxy, with radio emission filling giant bubble-shaped cavities. Also known as Perseus A, NGC 1275 spans over 100,000 light years and lies about 230 million light years away.

APOD: 2008 August 14 - Perseid Trail
Explanation: This bright and colorful meteor flashed through Tuesday's early morning skies, part of the annual Perseid Meteor Shower. The lovely image is one of over 350 frames captured on August 12 from the Joshua Tree National Park, in California, USA . Dust from comet Swift-Tuttle is responsible for the Perseids, creating the northern hemisphere's regular summer sky show. The comet dust is vaporized as it enters the atmosphere at upwards of 60 kilometers per second, producing visible trails that begin at altitudes of around 100 kilometers. Of course, the trails point back to a radiant point in the constellation Perseus, giving the meteor shower its name. Recorded after moonset, the starry background features the bright star Vega on the right. Extending below the western horizon is the faint band of the northern Milky Way.

APOD: 2008 June 6 - Two-Armed Spiral Milky Way
Explanation: Gazing out from within the Milky Way, our own galaxy's true structure is difficult to discern. But an ambitious survey effort with the Spitzer Space Telescope now offers convincing evidence that we live in a large galaxy distinguished by two main spiral arms (the Scutum-Centaurus and Perseus arms) emerging from the ends of a large central bar. In fact, from a vantage point that viewed our galaxy face-on, astronomers in distant galaxies would likely see the Milky Way as a two-armed barred spiral similar to this artist's illustration. Previous investigations have identified a smaller central barred structure and four spiral arms. Astronomers still place the Sun about a third of the way in from the Milky Way's outer edge, in a minor arm called the Orion Spur. To locate the Sun and identify the Milky Way's newly mapped features, just place your cursor over the image.

APOD: 2008 May 20 - The Perseus Cluster of Galaxies
Explanation: Here is one of the largest objects that anyone will ever see on the sky. Each of these fuzzy blobs is a galaxy, together making up the Perseus Cluster, one of the closest clusters of galaxies. The cluster is seen through a foreground of faint stars in our own Milky Way Galaxy. Near the cluster center, roughly 250 million light-years away, is the cluster's dominant galaxy NGC 1275, seen above as the large galaxy on the image left. A prodigious source of x-rays and radio emission, NGC 1275 accretes matter as gas and galaxies fall into it. The Perseus Cluster of Galaxies is part of the Pisces-Perseus supercluster spanning over 15 degrees and containing over 1,000 galaxies. At the distance of NGC 1275, this view covers about 7.5 million light-years.

APOD: 2007 December 21 - Horizon to Horizon
Explanation: Scroll right and journey from horizon to horizon as your gaze sweeps through the zenith in the night sky over Beg-Meil, France. Recorded on December 13th, the entertaining panorama (image key) covers 210 degrees in 21 separate exposures, beginning on the beach with bright star Sirius rising in the southeast. Look up (pan right) to encounter the nebula rich constellation of Orion and continue on to find the lovely Pleiades star cluster. Farther along, higher in the sky, is the famous Comet Holmes, still gracing the northern hemisphere's night with its remarkable expanding coma. Finally, just before diving into the urban glow from city lights along the northwestern horizon (far right), check out the double star cluster in Perseus and take in the cosmic streak of a bright Geminid Meteor.

APOD: 2007 December 7 - Double Cluster in Perseus
Explanation: Skygazers recently following Comet Holmes have probably also chanced across this lovely starfield, not far from the comet on the sky in the constellation Perseus. Some 7,000 light-years away, this pair of open or galactic star clusters is an easy binocular target and is visible to the unaided eye from dark sky areas. In fact, it was cataloged in 130 BC by Greek astronomer Hipparchus. Now known as h and chi Persei, or NGC 869(left) and NGC 884, the clusters themselves are separated by only a few hundred light-years and contain stars much younger and hotter than the Sun. In addition to being physically close together, the clusters' ages based on their individual stars are similar - evidence that both clusters were likely a product of the same star-forming region.

APOD: 2007 December 5 - Comet Holmes Over Hungary
Explanation: Comet Holmes refuses to fade. The unusual comet that surprisingly brightened nearly a million-fold in late October continues to remain visible to the unaided eye from dark locations. Night to night, Comet 17P/Holmes is slowly gliding through the constellation Perseus, remaining visible to northern observers during much of the night right from sunset. Pictured above, Comet Holmes was captured from Hungary last week. The remarkable snowball continues to retain a huge coma, but now shows very little of a tail. To the far right is the open cluster of stars NGC 1245. How much longer Comet Holmes will remain visible to the unaided eye is unknown.

APOD: 2007 November 29 - Stardust in Perseus
Explanation: This cosmic expanse of dust, gas, and stars covers some 4 degrees on the sky in the heroic constellation Perseus. Centered in the gorgeous skyscape is the dusty blue reflection nebula NGC 1333, about 1,000 light-years away. At that estimated distance, the field of view is nearly 70 light-years across. Other reflection nebulae are scattered around, along with remarkable dark dust nebulae and the faint reddish glow of hydrogen gas. These dust and gas clouds lie near the edge of a large molecular cloud. Themselves telltale signs of star-forming regions, they tend to hide the newly formed stars and young stellar objects or protostars from prying optical telescopes. Collapsing due to self-gravity, the protostars form around dense cores embedded in the molecular cloud.

APOD: 2007 November 28 - Comet Holmes from the Hubble Space Telescope
Explanation: Why did Comet Holmes brighten? The unexpectedly bright Comet 17P/Holmes continues to grace northern skies as a naked-eye addition to the constellation Perseus. Any northern sky enthusiast with a dark sky, a bright curiosity, and a recent sky map should still be able to locate the comet in a few minutes. What is seen, however, is primarily the sun-light reflecting dust coma. It surrounds an iceberg nucleus too small and too faint to discern. Clues to the nearly million-fold brightness increase are therefore being sought in dramatic images of the enigmatic comet's central regions taken earlier this month by the Hubble Space Telescope. One such Hubble image, shown above, indicates a still unresolved dense central dust cloud near the nucleus, surrounded by a more complex, anisotropic coma. The Hubble images do not show any obvious fragmentation of the nucleus, however, as was seen last year in Comet Schwassman-Wachmann 3. Observers around and above the world will continue to study this unusual addition to the night sky.

APOD: 2007 November 21 - Expansive Comet Holmes
Explanation: The spherical coma of Comet Holmes has swollen to a diameter of over 1.4 million kilometers, making the tenuous, dusty cloud even bigger than the Sun. Scattering sunlight, all that dust and gas came from the comet's remarkably active nucleus, whose diameter before the late October outburst was estimated to be a mere 3.4 kilometers. In this sharp image, recorded on November 14 with the Canada-France-Hawaii Telescope, stars are easily visible right through the outer coma, while the nucleus is buried inside the condensed, bright region. The bright region of the coma seems offset from the center, consistent with the idea that a large fragment drifted away from the nucleus and disintegrated, producing the comet's spectacular outburst. Of course, more recent images of Holmes also show the bright star Mirfak (Alpha Persei) shining through as the comet sweeps slowly through the constellation Perseus.

APOD: 2007 November 17 - Forest and Sky
Explanation: With pine trees in dim silhouette, this skyscape from Breil-sur-Roya in southern France was captured on November 11. In the early evening scene, a satellite seems to streak through the branches, while bright, round, fuzzy Comet Holmes appears to lie just beyond them, near the stars of the constellation Perseus. Mirfak, alpha star of Perseus, is the brightest star above the comet and to the right. Next Monday (November 19), Holmes will be close enough to Mirfak to view the star through the remarkable comet's expanding coma. Recent measurements place the dusty coma's diameter at about 1.4 million kilometers, even larger than the Sun.

APOD: 2007 November 13 - The Inner Coma of Comet Holmes
Explanation: What's happening to Comet Holmes? The rare comet remains visible to the unaided eyes of northern observers as an unusual small puff ball in the constellation of Perseus. A high resolution set of images of the comet's inner coma, taken last week and shown above, reveals significant detail. Close inspection shows numerous faint streamers that are possibly the result of jets emanating from the comet's nucleus. Comet Holmes has remained surprisingly bright over the past week, with luminosity estimates ranging from between visual magnitudes 2 to 3, making it brighter than most stars visible on a dark sky. The above image of Comet Holmes was made with a small automated 0.38-meter telescope hirable over the web for a small fee.

APOD: 2007 November 9 - Skyscape with Comet Holmes
Explanation: This gorgeous skyscape spans some 10 degrees across the heroic constellation Perseus, about the size of a generous binocular field of view. The deep exposure includes bright stars, emission nebulae, star clusters, and, of course, the famous Comet Holmes. To identify the celestial landmarks, just place your cursor over the image. The brightest star in view, Alpha Persei, is itself surrounded by a loose cluster of stars - the Alpha Per Moving Cluster - at a distance of about 600 light-years. But, at a distance of a mere 14 light-minutes bright Comet Holmes still dominates the scene with its fluorescing greenish coma and foreshortened blue tail.

APOD: 2007 November 3 - Golden Comet Holmes
Explanation: Surprising Comet Holmes remains easily visible as a round, fuzzy cloud in the northern constellation Perseus. Skywatchers with telescopes, binoculars, or those that just decide to look up can enjoy the solar system's latest prodigy as it glides about 150 million kilometers from Earth, beyond the orbit of Mars. Still expanding, Holmes now appears to be about 1/3 the size of the Full Moon, and many observers report a yellowish tint to the dusty coma. A golden color does dominate this telescopic view recorded on November 1, showing variations across the coma's bright central region. But where's the comet's tail? Like any good comet, Holmes' tail would tend to point away from the Sun. That direction is nearly along our line-of-sight behind the comet, making its tail very difficult to see.

APOD: 2007 October 26 - Comet Holmes in Outburst
Explanation: Comet 17P/Holmes stunned comet watchers across planet Earth earlier this week. On October 24, it increased in brightness over half a million times in a matter of hours. The outburst transformed it from an obscure and faint comet quietly orbiting the Sun with a period of about 7 years to a naked-eye comet rivaling the brighter stars in the constellation Perseus. Recorded on that date, this view from Tehran, Iran highlights the comet's (enhanced and circled) dramatic new visibility in urban skies. The inset (left) is a telescopic image from a backyard in Buffalo, New York showing the comet's greatly expanded coma, but apparent lack of a tail. Holmes' outburst could be due to a sudden exposure of fresh cometary ice or even the breakup of the comet nucleus. The comet may well remain bright in the coming days.

APOD: 2007 August 16 - Moonless Perseid Sky
Explanation: Last weekend, dark, moonless night skies brought many sightings of Perseid meteors to skygazers all over planet Earth. Early Sunday morning astronomer John Chumack's camera captured this Perseid meteor streak with a flare near the end of its track over Yellow Springs, Ohio. The single, four minute long exposure looks toward the constellation of Taurus and the eastern horizon. The meteor streak points back to the annual meteor shower's radiant in Perseus off the upper left corner of the picture. Of course, the view includes the well-known Pleiades Star cluster (near top center) with a bright yellowish planet Mars below it. Also seen with a yellowish tint but not quite as bright as Mars, the giant star Aldebaran anchors the V-shaped Hyades star cluster left of center, above the trees.

APOD: 2007 August 15 - Mysterious Streaks Over Turkey
Explanation: What are they? Five streaks near the bottom of the above image taken near Ankara, Turkey on Sunday would be identified at first glance as meteors from the Perseids meteor shower peaking just that night. Unexpectedly, however, these streaks do not point back to the Perseids radiant in Perseus. Their origin is therefore somewhat unclear. The above image was captured over the time span of 40 minutes. Other visible celestial icons include the constellation Orion and the Pleiades star cluster. One hypothesis is that the streaks are part of a microburst from a much less active meteor shower known as the Alpha Ursae Majorids. Another possibility is that they are parts of a satellite that broke up as it re-entered the Earth's atmosphere. A discussion of these possibilities can be found here. This year's Perseids meteor shower was a good one, as it was particularly active and corresponded with the dark skies that come with a new moon.

APOD: 2007 August 12 - Raining Perseids
Explanation: Tonight is a good night to see meteors. Comet dust will rain down on planet Earth, streaking through dark skies in the annual Perseid meteor shower. While enjoying the anticipated space weather, astronomer Fred Bruenjes recorded a series of many 30 second long exposures spanning about six hours on the night of 2004 August 11/12 using a wide angle lens. Combining those frames which captured meteor flashes, he produced this dramatic view of the Perseids of summer. Although the comet dust particles are traveling parallel to each other, the resulting shower meteors clearly seem to radiate from a single point on the sky in the eponymous constellation Perseus. The radiant effect is due to perspective, as the parallel tracks appear to converge at a distance. Bruenjes notes that there are 51 Perseid meteors in the composite image, including one seen nearly head-on. This year, the Perseids Meteor Shower is expected to peak after midnight tonight, in the moonless early morning hours of August 12.

APOD: 2007 May 21 - In the Center of Reflection Nebula NGC 1333
Explanation: The dust is so thick in the center of NGC 1333 that you can hardly see the stars forming. Conversely, the very dust clouds that hide the stars also reflects their optical light, giving NGC 1333's predominantly blue glow the general designation of a reflection nebula. A highly detailed image of the nebula, shown above, was taken recently by the Mayall 4-meter telescope on Kitt Peak in Arizona, USA and released to honor astronomer Stephen Strom on his retirement. Visible near the image top are vast blue regions of dust predominantly reflecting the light from bright massive stars. Visible in the thick central dust are not only newly formed stars but red jets and red-glowing gas energized by the light and winds from recently formed young stars. The NGC 1333 nebula contains hundreds of newly formed stars that are less than one million years old. Reflection nebula NGC 1333 lies about 1,000 light years away toward the constellation of Perseus.

APOD: 2007 March 31 - Hale-Bopp: The Great Comet of 1997
Explanation: Ten short years ago, Comet Hale-Bopp rounded the Sun and offered a dazzling spectacle in planet Earth's night. This stunning view, recorded shortly after the comet's perihelion passage on April 1, 1997, features the memorable tails of Hale-Bopp -- a whitish dust tail and blue ion tail. Here, the ion tail extends well over ten degrees across the northern sky, fading near the double star clusters in Perseus, while the head of the comet lies near Almach, a bright star in the constellation Andromeda. Do you remember Hale-Bopp? The photographer's sons do, pictured in the foreground at ages 12 and 15. In all, Hale-Bopp was reported as visible to the naked eye from roughly late May 1996 through September 1997.

APOD: 2006 October 6 - Dusty NGC 1333
Explanation: Dusty NGC 1333 is seen in visible light as a reflection nebula, dominated by bluish hues characteristic of starlight reflected by dust. But at longer infrared wavelengths, the interstellar dust itself glows. Moving your cursor over the picture will match up a visible light view with a false-color infrared image of the region from the Spitzer Space Telescope. The penetrating infrared view unmasks youthful stars that are otherwise obscured by the dusty clouds that formed them. Also revealed are greenish streaks and splotches that seem to litter the region. The structures trace the glow of cosmic jets blasting away from emerging young stellar objects and plowing into the cold cloud material. In all, the chaotic environment likely resembles one in which our own Sun formed over 4.5 billion years ago. NGC 1333 is a mere 1,000 light-years distant in the constellation Perseus.

APOD: 2006 August 17 - Comet Dust over Colorado
Explanation: The rock formation in the foreground of this night view was recorded on August 10, illuminated by light from a waning gibbous Moon. Even though the sky above also scatters the bright moonlight, a brilliant meteor was captured as it flashed across the scene during the 30 second long exposure. Of course, the meteor was part of the annual rain of dust from periodic Comet Swift-Tuttle known as the Perseid Meteor Shower. Leaving trails that point back to a radiant in the constellation Perseus, the ancient dust particles are vaporized as they enter the atmosphere at about 60 kilometers per second, their visible streaks beginning at altitudes of around 100 kilometers. And though it looks like the knuckles of a giant hand, the curious rock formation can be found in Colorado National Monument park, USA, planet Earth.

APOD: 2006 July 20 - Constellation Construction
Explanation: This lovely twilight scene, recorded last April, finds a young crescent Moon low in the west at sunset. Above it, stars shine in the darkening sky but they too are soon to drop below the western horizon. These stars and constellations are prominent in the northern hemisphere winter sky and as the season changes, slowly give way to the stars of summer. Sliding your mouse over the picture will detail the constellations and stars in view, including Orion, Gemini, Auriga, Perseus, and the Hyades and Pleiades star clusters.

APOD: 2006 May 25 - NGC 1579: Trifid of the North
Explanation: Colorful NGC 1579 resembles the better known Trifid Nebula, but lies much farther north in planet Earth's sky, in the heroic constellation Perseus. About 2,100 light-years away and 3 light-years across, NGC 1579 is a captivating study in color. Like the Trifid, NGC 1579 is a dusty star forming region providing contrasting emission and reflection nebulae in the same field - the characteristic red glow of hydrogen gas and the blue of reflected starlight. Also like the Trifid, dark dust lanes are prominent in the nebula's central regions. In fact, obscuring dust is pervasive in NGC 1579, drastically dimming the visible light from the massive, young, hot stars still embedded in the cosmic cloud.

APOD: 2006 April 13 - Star Cluster Dreams
Explanation: Located some 7,000 light-years away toward the constellation Perseus, this pair of open or galactic star clusters really is visible to the unaided eye and was cataloged in 130 BC by Greek astronomer Hipparchus. Now known as h and chi Persei (NGC 869/884), the clusters themselves are separated by a few hundred light-years and contain stars much younger, and hotter than the Sun. But what if this famous double star cluster were closer, say only 700 light-years distant from our fair solar system, crowding our sky with stars? Astrophotographer Jose Suro also imagines a clear, moonless, dark night sky on a warm evening near tranquil waters. The foreground is illuminated by starlight in his composited dreamlike image of the cluster pair. He notes that while the solar system is not in the vicinity of such rich clusters of stars, dark night skies and warm evenings can still be inspiring on planet Earth.

APOD: 2005 December 30 - The Perseus Cluster of Galaxies
Explanation: Here is one of the largest objects that anyone will ever see on the sky. Each of these fuzzy blobs is a galaxy, together making up the Perseus Cluster, one of the closest clusters of galaxies. The cluster is seen through a foreground of faint stars in our own Milky Way Galaxy. Near the cluster center, roughly 250 million light-years away, is the cluster's dominant galaxy NGC 1275, seen here just left of picture center. A prodigious source of x-rays and radio emission, NGC 1275 accretes matter as gas and galaxies fall into it. The Perseus Cluster of Galaxies is part of the Pisces-Perseus supercluster spanning over 15 degrees and containing over 1,000 galaxies. At the distance of NGC 1275, this view covers about 1.5 million light-years.

APOD: 2005 December 8 - X-Rays from the Perseus Cluster Core
Explanation: The Perseus Cluster of thousands of galaxies, 250 million light-years distant, is one of the most massive objects in the Universe and the brightest galaxy cluster in the x-ray sky. At its core lies the giant cannibal galaxy Perseus A (NGC 1275), accreting matter as gas and galaxies fall into it. This deep Chandra Observatory x-ray image spans about 300,000 light-years across the galaxy cluster core. It shows remarkable details of x-ray emission from the monster galaxy and surrounding hot (30-70 million degrees C) cluster gas. The bright central source is the supermassive black hole at the core of Perseus A itself. Low density regions are seen as dark bubbles or voids, believed to be generated by cyclic outbursts of activity from the central black hole. The activity creates pressure waves - sound waves on a cosmic scale- that ripple through the x-ray hot gas. Dramatically, the blue-green wisps just above centre in the false-color view are likely x-ray shadows of the remains of a small galaxy falling into the burgeoning Perseus A.

APOD: 2005 November 24 - Dusty NGC 1333
Explanation: Dusty NGC 1333 is seen as a reflection nebula in visible light images, sporting bluish hues characteristic of starlight reflected by dust. But at longer infrared wavelengths, the interstellar dust itself glows - shown in red in this false-color Spitzer Space Telescope image. The penetrating infrared view also shows youthful stars that would otherwise still be obscured by the dusty clouds which formed them. Notably, greenish streaks and splotches that seem to litter the region trace the glow of cosmic jets blasting away from emerging young stellar objects as the jets plow into the cold cloud material. In all, the chaotic scene likely resembles one in which our own Sun formed over 4.5 billion years ago. NGC 1333 is a mere 1,000 light-years distant in the constellation Perseus.

APOD: 2005 October 11 - NGC 869 and NGC 884: A Double Open Cluster
Explanation: Most star clusters are singularly impressive. Open clusters NGC 869 and NGC 884, however, are doubly impressive. Also known as "h and chi Persei", this unusual double cluster, shown above, is bright enough to be seen from a dark location without even binoculars. Although their discovery surely predates written history, the Greek astronomer Hipparchus notably cataloged the "double cluster". The clusters are over 7,000 light years distant toward the constellation of Perseus, but are separated by only hundreds of light years.

APOD: 2005 August 15 - Perseid Meteors and the Milky Way
Explanation: Where will the next Perseid meteor appear? Sky enthusiasts who trekked outside for the Perseid meteor shower that peaked over the past few days typically had this question on their mind. The above movie, where the time-line has been digitally altered, captures part of that very mystery. Eight meteors from the night of August 12 and the morning of August 13 have been identified in the movie so far, seven of which are Perseids. Can you identify the non-Perseid meteor? Since all Perseid meteors appear to come from the constellation of Perseus, the non-Perseid meteor is the one that streaks in a different direction. Early reports are that this year's Perseids were unfortunately a bit disappointing. The above digital mosaic was taken from Alsace, France, with the photogenic band of our Milky Way Galaxy far in the background.

APOD: 2005 August 12 - A Meteor Shower Fireball Movie
Explanation: Go outside tonight and see a celestial light show -- the later the better. Tonight is the peak of the month-long Perseid Meteor Shower. Although visible every year at this time, the Perseids are expected to appear particularly active this year due to the relative absence of glare from the Moon during the peak. Tonight, a thin moon will set a few hours after the Sun, leaving a moonless and dark sky. All through the night, all over the sky, meteors will appear to shoot out the constellation Perseus and across the sky. The rate of meteors and fireballs is not known for sure, but expected by some to be as high as one meteor flash every minute. Lucky sky gazers might be treated to a bright fireball like the one pictured above. That fireball was captured by a digital recorded over Wise Observatory during the 2001 Leonid Meteor Shower. The meteor shower poses no danger as few, if any, of the sand-sized flaring bits are expected to reach the ground.

APOD: 2005 August 6 - Raining Perseids
Explanation: Comet dust rained down on planet Earth last August, streaking through dark skies in the annual Perseid meteor shower. So, while enjoying the anticipated space weather, astronomer Fred Bruenjes recorded a series of many 30 second long exposures spanning about six hours on the night of August 11/12 using a wide angle lens. Combining those frames which captured meteor flashes, he produced this dramatic view of the Perseids of summer. Although the comet dust particles are traveling parallel to each other, the resulting shower meteors clearly seem to radiate from a single point on the sky in the eponymous constellation Perseus. The radiant effect is due to perspective, as the parallel tracks appear to converge at a distance. Bruenjes notes that there are 51 Perseid meteors in the composite image, including one seen nearly head-on. This year, the Perseids Meteor Shower will peak in the early morning hours on Friday, August 12.

APOD: 2005 July 25 - Unusual Gas Filaments Surround Galaxy NGC 1275
Explanation: How were the unusual gas filaments surrounding galaxy NGC 1275 created? No one is sure. Galaxy NGC 1275 is the central dominant galaxy of the Perseus Cluster of Galaxies, a cluster with many member galaxies visible in the above image. In visible light, NGC 1275 appears to show a spectacular collision between two distinct galaxies. The galaxy and cluster are also bright emitters of X-rays. The unusual gas filaments are shown above in a very specific color of light emitted by hydrogen, here artificially colored pink. Possible origins for the filaments may involve details of the collision between the two galaxies, or alternatively, interactions between a galactic center black hole and the surrounding intracluster gas. NGC 1275, pictured above, spans about 100,000 light years and lies about 230 million light years distant toward the constellation of Perseus.

APOD: 2005 January 5 - Comet Machholz in View
Explanation: Good views of Comet Machholz are in store for northern hemisphere comet watchers in January. Now making its closest approach to planet Earth, the comet will pass near the lovely Pleiades star cluster on January 7th and the double star cluster in Perseus on January 27th as Machholz moves relatively quickly through the evening sky. Currently just visible to the unaided eye from dark locations, the comet should be an easy target in binoculars or a small telescope. In fact, this telephoto time exposure from January 1 shows Comet Machholz sporting two lovely tails in skies over Colorado, USA. Extending to the left, strands of the comet's ion or gas tail are readily affected by the solar breeze and point away from the Sun. Dust, which tends to trail along the comet's orbit, forms the tail jutting down and to the right.

APOD: 2004 October 25 - The Perseus Cluster of Galaxies
Explanation: Here is one of the largest objects that anyone will ever see on the sky. Each of the fuzzy blobs in the above picture is a galaxy, together making up the Perseus Cluster, one of the closest clusters of galaxies. The cluster is seen through the foreground of faint stars in our own Milky Way Galaxy. It takes light roughly 300 million years to get here from this region of the Universe, so we see this cluster as it existed before the age of the dinosaurs. Also known as Abell 426, the center of the Perseus Cluster is a prodigious source of X-ray radiation, and so helps astronomers explore how clusters formed and how gas and dark matter interact. The Perseus Cluster of Galaxies is part of the Pisces-Perseus supercluster of galaxies, which spans over 15 degrees and contains over 1000 galaxies.

APOD: 2004 August 20 - Raining Perseids
Explanation: Comet dust rained down on planet Earth last week, streaking through dark skies in the annual Perseid meteor shower. So, while enjoying the anticipated space weather, astronomer Fred Bruenjes recorded a series of many 30 second long exposures spanning about six hours on the night of August 11/12 using a wide angle lens. Combining those frames which captured meteor flashes, he produced this dramatic view of the Perseids of summer. Although the comet dust particles are traveling parallel to each other, the resulting shower meteors clearly seem to radiate from a single point on the sky in the eponymous constellation Perseus. The radiant effect is due to perspective, as the parallel tracks appear to converge at a distance. Bruenjes notes that there are 51 Perseid meteors in the composite image, including one seen nearly head-on.

APOD: 2004 August 13 - Perseid Fireball Over Japan
Explanation: Enjoying the bright Moon's absence from early morning skies, observers around the world reported lovely displays during this year's Perseid meteor shower. As anticipated, peak rates were about one meteor per minute. Though most Perseids were faint, this bright and colorful fireball meteor flashed through skies over Japan on August 12 at 0317 JST. Ending at the upper right, the meteor's trail points down and to the left, back to the shower's radiant point between the constellations of Perseus and Cassiopeia, seen here just above the tower structure in the foreground. The Pleiades star cluster is also visible well below the meteor's trail. Perseid shower meteors can be traced to particles of dust from the tail of comet Swift-Tuttle. The comet dust impacts the atmosphere at speeds of around 60 kilometers per second. While this annual shower's peak has come and gone, Perseid meteors should still be visible over the next few nights, but at a greatly reduced rate.

APOD: 2004 August 11 - A Perseid Meteor
Explanation: The ongoing Perseid Meteor Shower should be at its strongest tonight and tomorrow night. Although meteors should be visible all night long, the best time to watch will be between 2:00 AM and dawn each night. In dark, moonless, predawn skies you may see dozens of meteors per hour. Sky enthusiasts in Europe and Asia might see an unusual burst of meteors near 2100 hours UT. Grains of cosmic sand and gravel shed from Comet Swift-Tuttle will streak across the sky as they vaporize during entry into Earth's atmosphere. Tracing the meteor trails backwards, experienced skygazers will find they converge on the constellation Perseus, thus this annual meteor shower's name. Pictured above is a Perseid meteor from 2002 over a rock formation in the US Southwest desert. Shadowing and blurring are caused by the long 10-minute exposure. The brightest Perseids can be seen from anywhere on Earth by monitoring the continuously returning images from the Night Sky Live cameras.

APOD: 2003 December 2 - NGC 869 and NGC 884: A Double Open Cluster
Explanation: Most star clusters are singularly impressive. Open clusters NGC 869 and NGC 884, however, are doubly impressive. Also known as "h and chi Persei", this unusual double cluster, shown above, is bright enough to be seen from a dark location without even binoculars. Although their discovery surely predates written history, the Greek astronomer Hipparchus notably cataloged the "double cluster". The clusters are over 7000 light years distant toward the constellation of Perseus, but are separated by only hundreds of light years.

APOD: 2003 September 12 - A Note on the Perseus Cluster
Explanation: A truly enormous collection of thousands of galaxies, the Perseus Cluster - like other large galaxy clusters - is filled with hot, x-ray emitting gas. The x-ray hot gas (not the individual galaxies) appears in the left panel above, a false color image from the Chandra Observatory. The bright central source flanked by two dark cavities is the cluster's supermassive black hole. At right, the panel shows the x-ray image data specially processed to enhance contrasts and reveals a strikingly regular pattern of pressure waves rippling through the hot gas. In other words, sound waves, likely generated by bursts of activity from the black hole, are ringing through the Perseus Galaxy Cluster. Astronomers infer that these previously unknown sound waves are a source of energy which keeps the cluster gas so hot. So what note is the Perseus Cluster playing? Estimates of the distance between the wave peaks and sound speed in the cluster gas suggests the cosmic note is about 57 octaves below B-flat above middle C.

APOD: 2003 August 9 - A Perseid Aurora
Explanation: Just after the Moon set but before the Sun rose in the early morning hours of 2000 August 12, meteors pelted the Earth from the direction of the constellation Perseus, while ions pelted the Earth from the Sun. The meteors were expected as sub-sand grains long left behind by Comet Swift-Tuttle annually create the Perseids Meteor Shower. The aurorae were unexpected, however, as electrons, protons, and heavier ions raced out from a large Coronal Mass Ejection that had occurred just days before on the Sun. In the foreground is Hahn's Peak, an extinct volcano in Colorado, USA. The Perseid meteor shower peaks this year over the next few days, with as much as one bright meteor per minute visible from some locations.

APOD: 2003 May 5 - NGC 1275: A Galactic Collision
Explanation: In NGC 1275, one galaxy is slicing through another. The disk of the dusty spiral galaxy near the image center is cutting through a large elliptical galaxy, visible predominantly on the lower left. Galaxies can change significantly during a collision like this, with gravitational tides distorting each galaxy and gas clouds being compressed and lighting up with new star formation. Galaxy collisions occur in slow motion to the human eye, with a single pass taking as much as 100 million years. NGC 1275 is a member of the Perseus cluster of galaxies that lies about 230 million light years away toward the constellation of Perseus. Each galaxy spans about 50,000 light years across. The above picture is a composite of images taken by the Hubble Space Telescope in 1995 and 2001.

APOD: 2002 August 15 - Meteors and Northern Lights
Explanation: Skygazers report that the annual Perseid meteor shower went pretty much as predicted, producing a meteor every few minutes during the dark early morning hours of August 12 and 13. And as the constellation Perseus rose above the horizon on the night of August 11, astrophotographer Wade Clark was anticipating recording images of the flashing meteor trails from the Mt. Baker Ski Area in northwest Washington, USA. But Clark was also treated to a colorful display of northern lights. As a result, the stars of Perseus are arrayed near the center of his well composed skyscape along with trails of Perseid meteors all viewed through the auroral glow. The alluring scene might look familiar to watchers of bygone Perseids. For many, views of the meteor shower in 2000 also coincided with auroral displays, courtesy of the active Sun.

APOD: 2002 August 11 - A Perseid Meteor
Explanation: The ongoing Perseid Meteor Shower should be at its strongest on August 12 and 13. The best time to watch will be between 2:00 AM and dawn on Monday morning (so plan on setting your alarm tonight!) and then again on Tuesday. In dark, moonless, predawn skies you may see dozens of meteors per hour. Grains of cosmic sand and gravel shed from Comet Swift-Tuttle will streak across the sky as they vaporize during entry into Earth's atmosphere. Tracing the meteor trails backwards, experienced skygazers will find they converge on the constellation Perseus, thus this annual meteor shower's name. Pictured above is a Perseid meteor from 1993. The colors are representative but digitally enhanced. As the meteor streaked across the night sky, different excited atoms emitted different colors of light. The origin of the green tinge visible at the right is currently unknown, however, and might result from oxygen in Earth's atmosphere.

APOD: 2001 August 10 - Perseids of Summer
Explanation: Like falling stardust, cast off bits of comet Swift-Tuttle hurtle through the upper atmosphere about this time each year as planet Earth passes near the comet's orbital path. For the northern hemisphere, this regular celestial display is known as the annual Perseid meteor shower -- so named because the meteor trails all appear traceable to a common "radiant point" in the constellation Perseus. This gorgeous wide-angle photo from the 1997 shower captures a 20-degree-long fireball meteor and another, fainter Perseid meteor trail in a rich area of the northern summer Milky Way. A labeled version is available identifying the shower's radiant point, surrounding deep-sky objects, and constellations. Easy to view (just go outside and look up!), the Perseid meteor shower will peak this weekend with maximum rates anticipated early Sunday morning, August 12, for eastern North America. Despite interfering moonlight, last year's faithful Perseid watchers were rewarded with bright meteors and extensive displays of the northern lights.

APOD: 2001 March 2 - LkHa101: The Hole in the Doughnut
Explanation: You'd need a really big cup of coffee with this doughnut ... because the hole in the middle is about a billion kilometers across. Centered on the Sun, a circle that size would lie between the orbits of Mars and Jupiter. In fact, this doughnut is known to surround a massive newborn star cataloged as LkHa 101 which lies in the constellation Perseus. Imaged in infrared light, the tantalizing torus-shaped cloud of gas and dust is slightly tilted to our view. The cloud's material may well be the ingredients for the formation of a distant solar system. A bright source of ultraviolet light, the hot young star itself is much fainter in the infrared and so not visible in this picture. Still, the star's presence is indicated as its intense stellar wind and radiation has apparently carved out the doughnut's hole. This premier close-up of a stellar system in formation was accomplished by adapting a powerful observational technique called interferometry to planet Earth's largest single mirror telescope, the 10 meter Keck.

APOD: 2000 October 31 - The Perseus Cluster s X Ray Skull
Explanation: This haunting image from the orbiting Chandra Observatory reveals the Perseus Cluster of Galaxies in x-rays, photons with a thousand or more times the energy of visible light. Three hundred twenty million light-years distant, the Perseus Cluster contains thousands of galaxies, but none of them are seen here. Instead of mere galaxies, a fifty million degree cloud of intracluster gas, itself more massive than all the cluster's galaxies combined, dominates the x-ray view. From this angle, voids and bright knots in the x-ray hot gas cloud lend it a very suggestive appearance. Like eyes in a skull, two dark bubbles flank a bright central source of x-ray emission. A third elongated bubble (at about 5 o'clock) forms a toothless mouth. The bright x-ray source is likely a supermassive black hole at the cluster center with the bubbles blown by explosions of energetic particles ejected from the black hole and expanding into the immense gas cloud. Fittingly, the dark spot forming the skull's "nose" is an x-ray shadow ... the shadow of a large galaxy inexorably falling into the cluster center. Over a hundred thousand light-years across, the Perseus Cluster's x-ray skull is a bit larger than skulls you may see tonight. Have a safe and happy Halloween!

APOD: 2000 August 21 - A Perseid Aurora
Explanation: Just after the Moon set but before the Sun rose in the early morning hours of August 12, meteors pelted the Earth from the direction of the constellation Perseus, while ions pelted the Earth from the Sun. The meteors were expected as sub-sand grains long left behind by Comet Swift-Tuttle annually create the Perseids Meteor Shower. The aurorae were unexpected, however, as electrons, protons, and heavier ions raced out from a large Coronal Mass Ejection that had occurred just days before on the Sun. In the foreground is Hahn's Peak, an extinct volcano in Colorado, USA.

APOD: 2000 June 15 - X-Rays From The Perseus Cluster Core
Explanation: The Perseus Cluster of thousands of galaxies, 320 million light-years distant, is one of the most massive objects in the Universe. At its core lies the giant cannibal galaxy Perseus A (NGC 1275), accreting matter as gas and galaxies fall into it. Representing low, medium, and high energy x-rays as red, green, and blue colours respectively, this Chandra X-ray Observatory image shows remarkable details of x-ray emission from this monster galaxy and surrounding hot (30-70 million degrees C) cluster gas. The bright central source is the supermassive black hole at the core of Perseus A itself. Dark circular voids just above and below the galaxy center, each about half the size of our own Milky Way Galaxy, are believed to be magnetic bubbles of energetic particles blown by the accreting black hole. Settling toward Perseus A, the cluster's x-ray hot gas piles up forming bright regions around the bubble rims. Dramatically, the long greenish wisp just above the galaxy's centre is likely the x-ray shadow produced by a small galaxy falling into the burgeoning Perseus A.

APOD: August 15, 1998 - The Perseus Cluster of Galaxies
Explanation: Here is one of the largest objects that anyone will ever see on the sky. Each of the fuzzy blobs in the above picture is a galaxy, together making up the Perseus Cluster, one of the closest clusters of galaxies. We view the cluster through the foreground of faint stars in our own Milky Way Galaxy. It takes light roughly 300 million years to get here from this region of the Universe, so we see this cluster as it existed before the age of the dinosaurs. Also known as Abell 426, the center of the Perseus Cluster is a prodigious source of X-ray radiation, and so helps astronomers explore how clusters formed and how gas and dark matter interact. The Perseus Cluster of Galaxies is part of the Pisces-Perseus supercluster of galaxies, which spans over 15 degrees and contains over 1000 galaxies.

APOD: January 26, 1998 - Interplanetary Spaceship Passes Earth
Explanation: Last Thursday an interplanetary spacecraft flew right past the Earth. The above images show sunlight momentarily reflected from this spacecraft's solar panels. No aliens were involved - the Near Earth Asteroid Rendezvous (NEAR) mission actually originated from Earth. Launched in 1996, NEAR zipped past the asteroid 253 Mathilde last June. This Earth flyby gravitationally deflects NEAR onto a trajectory passing the asteroid 433 Eros next year. Above, NEAR appears to move through the constellation of Perseus, as clouds created a changing diffuse white glow. NEAR was only visible for about 2 minutes from San Jose, California, where these image-intensified video camera observations were taken.

APOD: December 25, 1997 - A Hale Bopp Holiday
Explanation: Seen from the Pik Terskol Observatory in the northern Caucasus mountains, comet Hale-Bopp and the bright stars of the constellation Perseus hang above the snowy, moon-lit landscape. Although it reminds Northern Hemisphere dwellers of an idyllic Winter scene, this picture was actually recorded in the spring - on April 13th of this year. Seasons Greetings and Best Wishes from APOD!

APOD: April 26, 1997 - The Perseus Cluster of Galaxies
Explanation: Here is one of the largest objects that anyone will ever see on the sky. Each of the fuzzy blobs in the above picture is a galaxy, together making up the Perseus Cluster, one of the closest clusters of galaxies. We view the cluster through the foreground of faint stars in our own Milky Way Galaxy. It takes light roughly 300 million years to get here from there, so we only see this cluster as it existed during the age of the dinosaurs. Also known as Abell 426, the center of Perseus cluster is a prodigious source of X-ray radiation, and so helps astronomers study how clusters formed and how gas and dark matter interact. The Perseus Cluster of Galaxies is part of the Pisces-Perseus supercluster of galaxies, which spans over 15 degrees and contains over 1000 galaxies.

APOD: April 16, 1997 - A Star Cluster Through Hale-Bopp's Tail
Explanation: Comet Hale-Bopp continues to look impressive. The photograph above captured the comet on April 7^th passing nearly in front of M34, a star cluster in the constellation of Perseus. Many of the stars in this open cluster can be seen through Comet Hale-Bopp's white dust tail. The bright blue ion tail now shows several streams. Now receding from both the Sun and the Earth, Comet Hale-Bopp should still remain an impressive sight for weeks to come as it slowly fades.

APOD: January 29, 1997 - NGC 869 & NGC 884: A Double Open Cluster
Explanation: Most star clusters are singularly impressive. But open clusters NGC 869 and NGC 884 are doubly impressive. Also known as "h and chi Persei", this rare double cluster, shown above, is bright enough to be seen from a dark location without even binoculars. Although their discovery surely predates written history, the "double cluster" was notably cataloged by the Greek astronomer Hipparcos. The clusters are over 7000 light years distant toward the constellation of Perseus, but are separated by only hundreds of light years.

APOD: August 9, 1996 - The Perseid Meteor Shower
Explanation: From a radiant point in the constellation of Perseus, Comet Swift-Tuttle presents -- The Perseid Meteor Shower -- coming to your night sky this weekend! A bookish E. C. Herrick of New Haven, Connecticut correctly suspected in 1837 that this meteor shower was an annual event. Indeed it is now known to be a regular August shower caused by the yearly passage of the Earth through the orbiting debri left behind by periodic comet Swift-Tuttle. Since the bits of comet debri are moving along parallel orbits, on entering the atmosphere they leave fiery trails which appear to originate from a common radiant point in the sky, in this case in the constellation of Perseus. Dramatically illustrated in this composite video image made using MOVIE, meteors from the 1994 Perseids streak across the sky framed by the three bright stars of the asterism known as the "Summer Triangle". The image shows bright Perseids recorded that year from August 9 through 14. Here the trails appear nearly parallel as the camera was centered on the sky about 90 degrees from the radiant point. This year, European and North American observers should be able to view the shower near its maximum, about 90 meteors per hour, early Monday morning August 12, but the shower should be enjoyable on clear weekend nights (August 10,11) as well. After midnight is generally the best time for viewing. What's the best way to enjoy a meteor shower? Get a warm jacket and a comfortable lawnchair ... go outside and look up.

APOD: April 23, 1996 - Comet Hyakutake on a Starry Night
Explanation: It was a starry night in April (April 9th, 1996, 9:32 pm CDT to be exact) near Lone Jack, Missouri when Comet Hyakutake graced this astronomically rich field. Making an appearance as the brilliant evening star, Venus is overexposed at the far left. Just below Venus and slightly to the right, the Pleiades star cluster (M45) glistens. On the right hand side of the image, the comet itself shows a bright blue tail extending upwards past the nearby star cluster in the constellation Perseus (top right, the Alpha Persei Group). Hyakutake, receding from the Earth and appoaching the Sun, will sink into the western horizon at sunset in late April, disappearing from Northern Hemisphere skies.

APOD: April 5, 1996 - The Perseus Cluster of Galaxies
Explanation: Here is one of the largest objects that anyone will ever see on the sky. Each of the fuzzy blobs in the above picture is a galaxy, together making up the Perseus Cluster, one of the closest clusters of galaxies. We view the cluster through the foreground of faint stars in our own Milky Way galaxy. It takes light roughly 300 million years to get here from there, so we only see this cluster as it existed during the age of the dinosaurs. Also known as Abell 426, the center of Perseus cluster is a prodigious source of X-ray radiation, and so helps us study how clusters formed and how gas and dark matter interact. The Perseus Cluster of Galaxies is part of the Pisces-Perseus supercluster of galaxies, which spans over 15 degrees and contains over 1000 galaxies.