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.

2011 January 4
See Explanation.  Clicking on the picture will download
 the highest resolution version available.

A Green Flash from the Sun
Credit & Copyright: Juan José Manzano (Grupo de Observadores Astronómicos de Tenerife)

Explanation: Many think it is just a myth. Others think it is true but its cause isn't known. Adventurers pride themselves on having seen it. It's a green flash from the Sun. The truth is the green flash does exist and its cause is well understood. Just as the setting Sun disappears completely from view, a last glimmer appears startlingly green. The effect is typically visible only from locations with a low, distant horizon, and lasts just a few seconds. A green flash is also visible for a rising Sun, but takes better timing to spot. A dramatic green flash, as well as an even more rare blue flash, was caught in the above photograph recently observed during a sunset visible from Teide Observatory at Tenerife, Cannary Islands, Spain. The Sun itself does not turn partly green or blue -- the effect is caused by layers of the Earth's atmosphere acting like a prism.

Best Astronomy Images: APOD Editor to speak in Philadelphia tomorrow night and NYC Friday
Tomorrow's picture: open space

< | Archive | Index | Search | Calendar | RSS | Education | About APOD | Discuss | >

Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
NASA Official: Phillip Newman Specific rights apply.
NASA Web Privacy Policy and Important Notices
A service of: ASD at NASA / GSFC
& Michigan Tech. U.