Browse NASA Astronomy Picture of the Day archive by date and media: Archive Discoveries
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Scenes from Two Hemispheres
The stars of a summer night on the left and the winter night sky on the right are the same stars. In fact, both pictures were taken in late December and have similar fields of…
M94: A New Perspective
Beautiful island universe M94 lies a mere 15 million light-years distant in the northern constellation of the hunting dogs, Canes Venatici . A popular target for astronomers, the…
The Spider and The Fly
Bright clusters and nebulae abound in the ancient northern constellation of Auriga . The region includes the open star cluster M38 , emission nebula IC 410 with Tadpoles ,…
The Flame Nebula in Infrared
What lights up the Flame Nebula? Fifteen hundred light years away towards the constellation of Orion lies a nebula which, from its glow and dark dust lanes, appears, on the left,…
The Astronaut Who Captured a Satellite
In 1984, high above the Earth's surface, an astronaut captured a satellite. It was the second satellite captured that mission. Pictured above , astronaut Dale A. Gardner flies…
A Spherule from the Earth's Moon
How did this spherule come to be on the Moon? When a meteorite strikes the Moon , the energy of the impact melts some of the splattering rock , a fraction of which might cool into…
Andromeda Island Universe
The most distant object easily visible to the eye is M31 , the great Andromeda Galaxy some two and a half million light-years away. But without a telescope, even this immense…
The Mystery of the Fading Star
Every 27 years Epsilon Aurigae fades, remaining dim for roughly two years before growing bright again. Since the 19th century, astronomers have studied the mystery star,…
The Tail of the Small Magellanic Cloud
A satellite galaxy of our Milky Way, the Small Magellanic Cloud is wonder of the southern sky, named for 16th century Portuguese circumnavigator Ferdinand Magellan . Some 200,000…
The Spotty Surface of Betelgeuse
Betelgeuse really is a big star. If placed at the center of our Solar System it would extend to the orbit of Jupiter. But like all stars except the Sun, Betelgeuse is so distant…
A Roll Cloud Over Uruguay
What kind of cloud is this? A roll cloud . These rare long clouds may form near advancing cold fronts. In particular, a downdraft from an advancing storm front can cause moist…
Comet Halley's Nucleus: An Orbiting Iceberg
What does a comet nucleus look like? Formed from the primordial stuff of the Solar System, comet nuclei were thought to resemble very dirty icebergs. But ground-based telescopes…
A Force from Empty Space: The Casimir Effect
This tiny ball provides evidence that the universe will expand forever. Measuring slightly over one tenth of a millimeter, the ball moves toward a smooth plate in response to…
Blue Moon Eclipse
The International Year of Astronomy 2009 ended with a Blue Moon and a partial lunar eclipse , as the second Full Moon of December grazed the Earth's shadow on December 31st. The…
Not a Blue Moon
This bright Full Moon was captured on December 2nd, shining above a church overlooking the River Po, in Turin, Italy. It was the first Full Moon in December. Shining on…
Dust and the Helix Nebula
Dust makes this cosmic eye look red. The eerie Spitzer Space Telescope image shows infrared radiation from the well-studied Helix Nebula (NGC 7293) a mere 700 light-years away in…
Spitzer's M101
Big, beautiful spiral galaxy M101 is one of the last entries in Charles Messier's famous catalog, but definitely not one of the least. About 170,000 light-years across, this…
Rigel and the Witch Head Nebula
Double, double toil and trouble; Fire burn, and cauldron bubble -- maybe Macbeth should have consulted the Witch Head Nebula. This suggestively shaped reflection nebula on the…
Barred Spiral Galaxy NGC 6217
Many spiral galaxies have bars across their centers. Even our own Milky Way Galaxy is thought to have a modest central bar . Prominently barred spiral galaxy NGC 6217, pictured…
The Cat's Eye Nebula
Three thousand light-years away, a dying star throws off shells of glowing gas. This image from the Hubble Space Telescope reveals the Cat's Eye Nebula to be one of the most…
M51 Hubble Remix
The 51st entry in Charles Messier's famous catalog is perhaps the original spiral nebula - a large galaxy with a well defined spiral structure also cataloged as NGC 5194. Over…
A Graceful Arc
The graceful arc of the Milky Way begins and ends at two mountain peaks in this solemn night sky panorama. The view was created from a 24 frame mosaic, with exposures tracking…
Gamma Cas and Friends
Gamma Cassiopeiae shines high in northern autumn evening skies. The brightest spiky star in this rich and colorful Milky Way starfield, bluish Gamma Cas marks the central peak in…
December Sunrise, Cape Sounion
The Sun is a moving target . Its annual motion through planet Earth's sky tracks north and south, from solstice to solstice, as the seasons change . On December 21st, the solstice…
Viewing discoveries from 15 January 2010 through 23 December 2009.