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Tuesday, July 4, 2000

Lunar eclipse, comet
will excite Hawaii skies

By Helen Altonn


Hawaii residents are in a choice spot to see a total lunar eclipse in the early hours of July 16 if rain and clouds don't mar the view.

It will be the last one visible here for seven years.

Comet LINEAR also is appearing this month -- the first comet visible without binoculars since Hale-Bopp's spectacular showing in 1997.

"It should be a pretty exciting month for astronomy," said Mike Shanahan, Bishop Museum Planetarium manager.

The last total eclipse of the moon that could have been seen here was Jan. 20. "It would have been a beautiful eclipse but the weather was terrible," Shanahan said.

The coming eclipse also "should be really beautiful" if the weather is favorable, he said.

The moon will begin darkening at 1:57 a.m. on July 16 with a partial eclipse.

The total phase, with the moon completely within the Earth's dark inner shadow, will start at 3:05 a.m. and last 1 hour and 47 minutes.

Waves of red sunlight passing the Earth and illuminating the moon will give it a ruddy color, even in totality, Shanahan said.

The moon during this eclipse will be passing through almost the exact center of the Earth's umbra, Shanahan said. As a result, it will be the longest total lunar eclipse since 1859 and the longest until at least the 22nd century, he said.

"It will definitely be worth staying up late if you're a night owl or rising early if you're a morning person.

"It will be the last chance to see it in a long time from this part of the world."

The moon will rise at sunset July 15 and be above the south by midnight, Shanahan said. It will be in the western part of the sky by the time the eclipse begins just before 2 a.m. on the 16th, he said.

Comet LINEAR already can be seen with a good telescope in the early morning skies, about 3:30 to 4 a.m., Shanahan said. It's low in the northwest in the Perseus constellation.

It will be in the faint constellation of Camelopardalis when the lunar eclipse occurs.

To find that part of the sky, Shanahan said, find the Little Dipper and follow its handle, then go one more handle-length beyond the North Star, which is the end of the Little Dipper's handle.

Try that about 1 a.m. July 16 while waiting for the lunar eclipse, he said.

The comet is predicted to be anywhere from 5.6 magnitude, which is very dim, to about 2 magnitude, as bright as the North Star, he said.

Hale-Bopp three years ago was brilliant but Kohoutek in the early 1970s was a big bust, Shanahan noted, describing the difficulties of predicting comets.

New comets that haven't been around the sun much have a frosting of chemicals or volatiles that glow abnormally bright when they first encounter heat from the sun between the orbits of Uranus and Saturn, he said.

That may give a false impression that the the comet will be even brighter when it nears the Sun, but with the volatile materials burned off, the result could be a bust, he said.

"I think that's what the Kohoutek problem came from.... With Kohoutek, and this comet, if it hasn't been near the sun, it will glow abnormally bright when it's near Saturn, but won't be a whole lot brighter.

"The issue is, we just don't know if this is a new comet or an old comet, and that deeply affects how bright it will be.

"It's out of our hands. It's the chemical composition of the comet that will determine if we have a very interesting or bright comet.

But "it will be exciting," Shanahan added. He said he's never seen a comet during a lunar eclipse so he doesn't know if it will be brighter because of the blackout.

LINEAR from July 19-25 will pass just below the Big Dipper.

Look for it on July 22, when the comet is closest to the Earth and will be the brightest, Shanahan said. It will be visible in the evening hours and the moon won't rise until after midnight.

LINEAR will disappear into the twilight in early August.

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