Astronomy Picture of the Day

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

2003 March 21
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Stars and Planets in the Halo of the Moon
Credit & Copyright: Lauri Kangas

Explanation: Photographed on March 13th from Caledon, Ontario, Canada, a bright Moon was surrounded by this lovely halo. Planet Jupiter and stars Procyon, Castor, and Pollux also appear within the circle of lunar light. Castor and Pollux, twins in Greek Mythology, are appropriately bright stars of the constellation Gemini while Procyon is the brightest star in Canis Minor. The circular halo is produced by six-sided ice crystals in thin high-altitude clouds, which refract the moonlight and give the halo a characteristic radius of 22 degrees. For persistent skygazers such apparitions are relatively easy to see when the Moon and Sun illuminate planet Earth's skies.

Tomorrow's picture: celestial band

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