If the clouds aren’t too thick tonight, sky watchers are in for a rare treat: A full lunar eclipse with a sideshow to boot.

Tonight’s eclipse, the last until 2010, is expected to peak around 10 p.m. when the moon will be fully covered by the earth’s shadow. Observers also will be able to see the planet Saturn and the star Regulus on either side of the moon during the event.

However, cloudy skies are expected tonight in North Georgia, which could put a damper on the show.

Those without a telescope who would like to get a good view can visit the North Georgia Astronomical Observatory at North Georgia College & State University in Dahlonega. The telescope is in the George S. Coleman Planetarium in the Health and Natural Sciences Building on campus, and opens on clear nights at 7:30 p.m. to visitors. Best to call beforehand at 706-864-8642 for its status.

Tonight’s will be the last total lunar eclipse until Dec. 20, 2010. Last year there were two.

Later this year, in August, there will be a total solar eclipse and a partial lunar eclipse.

A total lunar eclipse occurs when the full moon passes into Earth’s shadow and is blocked from the sun’s rays that normally illuminate it. During an eclipse, the sun, Earth and moon line up, leaving a darkened moon visible to observers on the night side of the planet.

The moon doesn’t go black because indirect sunlight still reaches it after passing through the Earth’s atmosphere. Since the atmosphere filters out blue light, the indirect light that reaches the moon transforms it into a reddish or orange tinge, depending on how much dust and cloud cover are in the atmosphere at the time.

Unlike solar eclipses which require protective eyewear, lunar eclipses are safe to view with the naked eye.

Robert Webb, astronomer with Elachee Nature Science Center, said tonight’s sky may not be completely overcast and there could be breaks in the clouds. Elachee is planning to hold a members-only eclipse event, “rain or shine.”

“The Earth’s shadow will start to move across the moon at about 8:45 p.m.,” Webb said. “You’ll be able to see the round shape of the Earth.”

Webb said the total phase will start at 10 p.m. and last until about 10:50 p.m., with the trailing edge of Earth’s shadow clearing the moon at about midnight.

The total phase of a lunar eclipse lasts longer than that of a solar eclipse, Webb said, because the Earth’s shadow is much bigger than the moon.

Times staff writer Debbie Gilbert contributed to this story.