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.

2002 August 11
See Explanation.  Clicking on the picture will download
 the highest resolution version available.

A Perseid Meteor
Credit & Copyright: S. Kohle & B. Koch, Bonn University

Explanation: The ongoing Perseid Meteor Shower should be at its strongest on August 12 and 13. The best time to watch will be between 2:00 AM and dawn on Monday morning (so plan on setting your alarm tonight!) and then again on Tuesday. In dark, moonless, predawn skies you may see dozens of meteors per hour. Grains of cosmic sand and gravel shed from Comet Swift-Tuttle will streak across the sky as they vaporize during entry into Earth's atmosphere. Tracing the meteor trails backwards, experienced skygazers will find they converge on the constellation Perseus, thus this annual meteor shower's name. Pictured above is a Perseid meteor from 1993. The colors are representative but digitally enhanced. As the meteor streaked across the night sky, different excited atoms emitted different colors of light. The origin of the green tinge visible at the right is currently unknown, however, and might result from oxygen in Earth's atmosphere.

Tomorrow's picture: Monday's child

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Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (USRA)
NASA Technical Rep.: Jay Norris. Specific rights apply.
A service of: LHEA at NASA/ GSFC
& Michigan Tech. U.