Browse NASA Astronomy Picture of the Day archive by date and media: Archive Discoveries
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Comet Hartley Passes a Double Star Cluster
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 ,…
Water Ice Detected Beneath Moon's Surface
Is there enough water on the moon to sustain future astronauts? The question has important implications if humanity hopes to use the Moon as a future outpost. Last year , to help…
A Bucket-Wheel Excavator on Earth
Please wait while one of the largest mobile machines in the world crosses the road. The machine pictured above is a bucket-wheel excavator used in modern surface mining . Machines…
Orion: Head to Toe
Cradled in cosmic dust and glowing hydrogen, stellar nurseries in Orion the Hunter lie at the edge of a giant molecular cloud some 1,500 light-years away. Spanning nearly 25…
NGC 7822 in Cepheus
Pillars of gas, dust, and young, hot stars seem to fill the gaping maw of NGC 7822. At the edge of a giant molecular cloud toward the northern constellation Cepheus , the glowing…
Methuselah Nebula MWP1
The lovely, symmetric planetary nebula cataloged as MWP1 lies some 4,500 light-years away in the northern constellation Cygnus the Swan. One of the largest planetary nebulae…
Venus Just After Sunset
Is that Venus or an airplane? A common ponderable for sky enthusiasts is deciding if that bright spot near the horizon is the planet Venus. Usually, an airplane will show itself…
Prometheus Rising Through Saturn's F Ring
What is that dark streak below Prometheus? Although it may look like a shadow or a trail blazed by sweeping up material, computer simulations indicate that the dark streak is…
It Came from the Sun
What's that coming over the edge of the Sun? What might appear at first glance to be some sort of Sun monster is actually a solar prominence . The above prominence , captured by…
NGC 346 in the Small Magellanic Cloud
How and why are all these stars forming? Found among the Small Magellanic Cloud's (SMC's) clusters and nebulae NGC 346 is a star forming region about 200 light-years across,…
The Large Cloud of Magellan
The 16th century Portuguese navigator Ferdinand Magellan and his crew had plenty of time to study the southern sky during the first circumnavigation of planet Earth. As a result,…
Vista with NGC 2170
Drifting through the one-horned constellation Monoceros , these dusty streamers and new born stars are part of the active Monoceros R2 star-forming region, embedded in a giant…
Clusters, Hartley, and the Heart
An alluring Comet Hartley 2 cruised through planet Earth's night sky on October 8, passing within about a Full Moon's width of the famous double star cluster in Perseus. The much…
Science Museum Hubble
Will the Hubble Space Telescope (HST) end up in a museum? Probably not, as when it finally goes bust, current plans call for it to be de-orbited into an ocean. But this won't stop…
Saturn: Light, Dark, and Strange
What's creating those dark bands on Saturn? Sometimes it takes a little sleuthing to figure out the how and why of a picture taken by the Saturn-orbiting Cassini spacecraft. Let's…
NGC 2683: Spiral Edge-On
Does spiral galaxy NGC 2683 have a bar across its center? Being so nearly like our own barred Milky Way Galaxy, one might guess it has. Being so nearly edge-on, however, it is…
Moonquakes Surprisingly Common
Why are there so many moonquakes? A recent reanalysis of seismometers left on the moon by the Apollo moon landings has revealed a surprising number of moonquakes occurring within…
Globular Star Cluster NGC 6934
Globular star clusters roam the halo of our Milky Way Galaxy. Gravitationally bound , these spherical groupings of typically several hundred thousand stars are ancient, older than…
Two Planet Opposition
In late September, two planets were opposite the Sun in Earth's sky, Jupiter and Uranus. Consequently closest to Earth, at a distance of only 33 light-minutes and 2.65 light-hours…
Pacman and Hartley
Touring the solar system with a 6 year orbital period , small comet Hartley 2 (103/P Hartley) will make its closest approach to planet Earth on October 20 and its closest approach…
Aurora Over Alaska
Are those green clouds or aurora? Photographed above two weeks ago, puffy green aurora help the Moon illuminate the serene Willow Lake and the snowy Wrangell and Saint Elias…
Horsehead and Orion Nebulas
The dark Horsehead Nebula and the glowing Orion Nebula are contrasting cosmic vistas. Adrift 1,500 light-years away in one of the night sky's most recognizable constellations ,…
Rolling Across the Rocky Plains of Mars
You stare out across the rocky plains of Mars. Before you, in every direction, is dark sand and bright rock. Although little has changed here for millions of years, no one has…
Io in True Color
The strangest moon in the Solar System is bright yellow. This picture , an attempt to show how Io would appear in the “true colors” perceptible to the average human eye, was taken…
Viewing discoveries from 26 October 2010 through 3 October 2010.