Los Angeles ? If the weather cooperates, a total lunar eclipse will be seen across North America late Thursday — the first visible in the United States in three years — and just before dawn Friday in western Europe as well as western and southern Africa.

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.

In North America, the moon will remain totally eclipsed for 53 minutes, and it is expected to turn substantially darker and reddish in color.

The total eclipse will start at 8:13 PDT in Los Angeles. It would be visible in Kansas at 10:13 p.m. CDT.

A second lunar eclipse, on Nov. 8, will be visible from North and South America.

Unlike solar eclipses, lunar eclipses are safe to view with the naked eye.

Eclipses once helped prove the Earth is round, because its shadow on the moon is curved.