Mark your calendars

For the first time in three years, a total lunar eclipse will be visible in the United States late Thursday night. Curious skywatchers in western Europe and western and southern Africa can view the eclipse just before dawn Friday.

In North America, the moon will remain totally eclipsed for 53 minutes, and should turn substantially darker and reddish in color. The eclipse will start at 8:13 PDT in Los Angeles, 11:13 p.m. EDT in New York.

A lunar eclipse occurs when the Earth casts its shadow on the full moon, blocking the sunlight that otherwise reflects off the moon's surface. Unlike solar eclipses, lunar eclipses are safe to view with the naked eye.

If you miss this one, mark your calendars - a second lunar eclipse will be visible from North and South America on 8 November, 2003.