November 20, 2012
Billions of years of cosmic evolution — the birth and death of stars, the slow coalescence of planets, the patient unfolding of life — all...
A Halo Around the Moon
Birthday · November 20, 2012
A little universe, just for you
Your date.
Ready to give.
Free PNG · 1080 × 1350 · No account needed
Image rights and credit requirements apply when sharing or reusing imagery.
Date & occasion only
Change the year
APOD published November 20, 2012. Credit: Anthony Ayiomamitis. A publication-date match, not a photo taken on your date. Independent of NASA.
Have you ever seen a halo around the Moon? This fairly common sight occurs when high thin clouds containing millions of tiny ice crystals cover much of the sky. Each ice crystal acts like a miniature lens. Because most of the crystals have a similar elongated hexagonal shape, light entering one crystal face and exiting through the opposing face refracts 22 degrees, which corresponds to the radius of the Moon Halo. A similar Sun Halo may be visible during the day. The setting of the above picture is Athens, Greece. The distant planet Jupiter appears by chance on the halo's left. Exactly how ice-crystals form in clouds remains under investigation.
Image credit: Anthony Ayiomamitis