Browse NASA Astronomy Picture of the Day archive by date and media: Archive Discoveries
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Polaris and Comet Lovejoy
One of these two bright sky objects is moving. On the right is the famous star Polaris. Although only the 45th brightest star in the sky, Polaris is famous for appearing…
Pulsating Aurora over Iceland
Why do some auroras pulsate? No one is sure. Although this unusual behavior has been known for a long time, the cause remains an active topic of research. Featured here is a…
Supernova 1994D and the Unexpected Universe
Long ago, far away, a star exploded. Supernova 1994D , visible as the bright spot on the lower left, occurred in the outskirts of disk galaxy NGC 4526 . Supernova 1994D was not of…
Messier Craters in Stereo
Many bright nebulae and star clusters in planet Earth's sky are associated with the name of astronomer Charles Messier , from his famous 18th century catalog. His name is also…
Saturn at Opposition
Telescopic observers on Earth have been treated to spectacular views of Saturn lately as the ringed planet reached its 2015 opposition on May 23 at 0200 UT. Of course opposition…
Nearby Spiral Galaxy NGC 4945
Large spiral galaxy NGC 4945 is seen edge-on near the center of this cosmic galaxy portrait . In fact, NGC 4945 is almost the size of our own Milky Way Galaxy . Its own dusty…
Approaching Pluto
Here comes Pluto. NASA's robotic New Horizons spacecraft is now beyond the orbit of Neptune and closing fast on the Solar System's most famous unexplored world. The featured time…
Starburst Galaxy M94
What could cause the center of M94 to be so bright? Spiral galaxy M94 has a ring of newly formed stars surrounding its nucleus, giving it not only an unusual appearance but also a…
The Galaxy Tree
First came the trees. In the town of Salamanca , Spain , the photographer noticed how distinctive a grove of oak trees looked after being pruned . Next came the galaxy. The…
Space Shuttle Rising
What's that rising from the clouds? The space shuttle. Sometimes, if you looked out the window of an airplane at just the right place and time, you could have seen something very…
NGC 7822 in Cepheus
Hot, young stars and cosmic pillars of gas and dust seem to crowd into NGC 7822. At the edge of a giant molecular cloud toward the northern constellation Cepheus, the glowing star…
A Dark and Dusty Sky
In the dusty sky toward the constellation Taurus and the Orion Arm of our Milky Way Galaxy, this broad mosaic follows dark and faint reflection nebulae along the region's fertile…
NGC 6240: Merging Galaxies
NGC 6240 offers a rare, nearby glimpse of a cosmic catastrophe in its final throes. The titanic galaxy-galaxy collision takes place a mere 400 million light-years away in the…
A Cliff Looming on Comet 67P
What's that looming behind this gravel-strewn hill on Comet ChuryumovGerasimenko? A jagged cliff. The unusual double-lobed nucleus of Comet 67P/ChuryumovGerasimenko lends itself…
Globular Star Cluster 47 Tuc
Globular star cluster 47 Tucanae is a jewel box of the southern sky. Also known as NGC 104 , it roams the halo of our Milky Way Galaxy along with over 150 other globular star…
Auroras and Star Trails over Iceland
It was one of the quietest nights of aurora in weeks. Even so, in northern- Iceland during last November, faint auroras lit up the sky every clear night. The featured 360-degree…
NGC 2440: Pearl of a New White Dwarf
Like a pearl , a white dwarf star shines best after being freed from its shell. In this analogy, however, the Sun would be a mollusk and its discarded hull would shine prettiest…
Ares 3 Landing Site: The Martian Revisited
This close-up from the Mars Reconnaissance Orbiter's HiRISE camera shows weathered craters and windblown deposits in southern Acidalia Planitia . A striking shade of blue in…
Jupiter, Ganymede, Great Red Spot
In this sharp snapshot, the Solar System's largest moon Ganymede poses next to Jupiter, the largest planet. Captured on March 10 with a small telescope from our fair planet Earth,…
Dwarf Planet, Bright Spot
Now at Ceres, Dawn's camera recorded this closer view of the dwarf planet's northern hemisphere and one of its mysterious bright spots on May 4. A sunlit portrait of a small, dark…
The Magnificent Horsehead Nebula
Sculpted by stellar winds and radiation, a magnificent interstellar dust cloud by chance has assumed this recognizable shape. Fittingly named the Horsehead Nebula , it is some…
Two Worlds, One Sun
How different does sunset appear from Mars than from Earth? For comparison, two images of our common star were taken at sunset , one from Earth and one from Mars. These images…
The Sky from Mauna Kea
What if you could stand at the top of a volcano and peer out across the universe? If the timing is right, you might see an amazing panorama like the one featured here . In this…
MyCn18: An Hourglass Planetary Nebula
The sands of time are running out for the central star of this hourglass-shaped planetary nebula . With its nuclear fuel exhausted, this brief, spectacular, closing phase of a…
Viewing discoveries from 2 June 2015 through 10 May 2015.