Hawai'i residents who stay up late tonight will be treated to an unusually showy full eclipse of the moon.

Weather permitting, residents across the state will be able to see the full moon disappear in the shadow of the Earth for about 90 minutes starting about 11:52 p.m.

The eclipse means that the normally bright full moon will appear as a reddish-orange orb almost directly over the Islands, said Carolyn Kaichi, manager of the Bishop Museum Planetarium, which has several special events planned for the night.

"That's the really spectacular part, when we see what it looks like, because it's always different, depending on what's in the atmosphere at the time of the eclipse," Kaichi said.

If the Earth had no atmosphere, the moon would be invisible in the eclipse. Instead, the moon's appearance darkens into an eerie copper color as light from the sun is filtered through the Earth's atmosphere and indirectly reaches the moon.

While lunar eclipses occur fairly regularly, they aren't always visible from Hawai'i. And when they can be seen here, the viewing conditions aren't always optimal. During the last big eclipse visible in Hawai'i, in 2003, for instance, the eclipse began just as the moon was rising and there was still some lingering daylight, Kaichi said.

Tonight's eclipse, however, promises to occur at a time when the moon is well overhead, allowing residents to see the entire eclipse, which lasts about three and a half hours. "We won't get such a good eclipse viewing again until 2010," Kaichi said.

The moon will start to go into the shadow of the Earth at 10:51 tonight and be fully eclipsed by 11:52 p.m. It will start to emerge from the shadow at 1:22 a.m., and be out of the partial eclipse stage at 2:24 a.m.

"Such a rare astronomical event is worth celebrating and letting your kids stay up late to see for themselves," Kaichi said.

For those who don't want to loll around the house all evening, the Bishop Museum will celebrate the event with a full schedule of activities on the grounds starting at 9:30 p.m. The events include several astronomical lectures, presentations in the planetarium, demonstrations of geocaching (a sort of treasure hunt using global positioning systems) and — of course — telescopes set up to give people an up-close view of the eclipse.

Admission is $3 per person. Parking in the Bishop Museum parking lot is free.

Reach Mike Leidemann at mleidemann@honoluluadvertiser.com.