Astronomy Picture of the Day

Discover the cosmos! Each day we feature a different image or photograph of our fascinating universe, along with a brief explanation written by a professional astronomer.

November 18, 1995

Water World
Credit: NASA, STS-45 Crew.

Explanation: Water (Dihydrogen Oxide, H2O) is a truly remarkable chemical compound and is fundamental to life on Earth. Earth is the only planet in the Solar System where the surface temperature and pressure allow the three forms of water, solid (ice), liquid (ocean), and gas (water vapor condensing in clouds) to exist simultaneously on its surface. Water in one of these forms accounts for everything visible in this view of Earth from space looking north at the Bering Sea and the coast of Alaska, USA, around Bristol Bay.

Tomorrow's picture: New York at Night

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Authors & editors: Robert Nemiroff (GMU) & Jerry Bonnell (USRA).
NASA Technical Rep.: Sherri Calvo. Specific rights apply.
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