Astronomy Picture of the Day

photo Milky Way over Pyramid of the Feathered Serpent

Milky Way over Pyramid of the Feathered Serpent

To see the feathered serpent descend the Mayan pyramid requires exquisite timing. You must visit El Castillo -- in Mexico's Yucatán Peninsula -- near an equinox. Then, during the late afternoon if the sky is clear, the pyramid's own shadows ...

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photo Unusual Mountain Ahuna Mons on Asteroid Ceres

Unusual Mountain Ahuna Mons on Asteroid Ceres

What created this unusual mountain? There is a new theory. Ahuna Mons is the largest mountain on the largest known asteroid in our Solar System, Ceres, which orbits our Sun in the main asteroid belt between Mars and Jupiter. Ahuna Mons, though, ...

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photo Stereo Helene

Stereo Helene

Get out your red/blue glasses and float next to Helene, small, icy moon of Saturn. Appropriately named, Helene is one of four known Trojan moons, so called because it orbits at a Lagrange point. A Lagrange point is a gravitationally stable ...

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photo NGC 4676: The Mighty Mice

NGC 4676: The Mighty Mice

These two mighty galaxies are pulling each other apart. Known as The Mice because they have such long tails, each large spiral galaxy has actually passed through the other. Their long tails are drawn out by strong gravitational tides rather than ...

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photo The Colors and Magnitudes of M13

The Colors and Magnitudes of M13

M13 is modestly recognized as the Great Globular Star Cluster in Hercules. A ball of stars numbering in the hundreds of thousands crowded into a region 150 light years across, it lies some 25,000 light-years away. The sharp, color picture of M13 ...

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photo Spiral Galaxy M96 from Hubble

Spiral Galaxy M96 from Hubble

Dust lanes seem to swirl around the core of Messier 96 in this colorful, detailed portrait of the center of a beautiful island universe. Of course M96 is a spiral galaxy, and counting the faint arms extending beyond the brighter central region, ...

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photo The Cave Nebula in Infrared from Spitzer

The Cave Nebula in Infrared from Spitzer

What's happening in and around the Cave Nebula? To help find out, NASA's orbiting Spitzer Space Telescope looked into this optically-dark star-forming region in four colors of infrared light. The Cave Nebula, cataloged as Sh2-155, is quite ...

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photo Jupiter Abyss

Jupiter Abyss

What's that black spot on Jupiter? No one is sure. During the latest pass of NASA's Juno around Jupiter, the robotic spacecraft imaged an usually dark cloud feature informally dubbed the Abyss. Surrounding cloud patterns show the Abyss to be at ...

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photo A Triangular Shadow of a Large Volcano

A Triangular Shadow of a Large Volcano

Why does the shadow of this volcano look like a triangle? The Mount Teide volcano itself does not have the strictly pyramidal shape that its geometric shadow might suggest. The triangle shadow phenomena is not unique to the Mt. Teide, though, ...

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photo On the Beach with Mars

On the Beach with Mars

At the end of last year's northern summer, after its dazzling opposition, Mars still shone brightly in the night. The celestial beacon easily attracted the attention of these two night skygazers who stood still for just a while, but long enough ...

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