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Project Comet Chaser

By now, you have probably seen something about the rocket launch from Ninigret Park on November 18th in the news. Local area students have assembled a payload which is mounted in a rocket that with be launched by a NASA crew of specialists. With luck, this payload will catch dust from the tail of a comet. Students will analyze this material over the coming months if all goes well.

The comet is named Tempel-Tuttle after its discoverers. It orbits the Sun once every 331/4 years. The size of the Earth's average distance from the Sun is one astronomical unit or an AU. At the comet's closest approach, it will be just inside the Earth's orbit (0.97 AU). At its farthest, the comet will be more than 21 AUs from the Sun. Tempel-Tuttle sheds dust particles as the Sun evaporates its icy core. If you think you can't see something as tiny as a dust particle sixty or seventy miles above the Earth, you'd be wrong. Dust (and larger) particles hitting the Earth's atmosphere are meteors. This particular swarm is called the Leonids because the meteors seem to fly across the sky from a point in the constellation Leo (the Lion).

When Project Comet Chaser was in its planning stage, Frosty Drew Observatory was asked if it could provide some sort of an activity at the dome. After all, the launch site is less than a quarter mile from our building. It seemed appropriate to do some sort of a demonstration involving the comet. Students who come over to the dome can see our new telescope and watch a simulation of the Tempel-Tuttle pass through the inner solar system. We show an animation riding Tempel-Tuttle through the solar system, an animation of Temple-Tuttle in the sky above Charlestown and an animation from 20 AUs out from the Sun about 15o above the plane of the Earth's orbit. Together these give a very dramatic sense of what the comet's motion is like.

It would have been quite a chore if we had to write all this software ourselves. Luckily, some commercially available software we use to control our telescope is capable of doing this with a little help from the International Astronomical Union[IAU]. The IAU data base contains orbital information for thousands of comets and asteroids. Once we matched the two sets of data, we experimented with lots of ways to show the encounter and finally selected these simulations as the best.

The Leonid meteor shower are predicted to be heavy this year because we will be passing through a newly refreshed particle stream. Predicting meteor shower intensities is fraught with uncertainty. The most intense displays will probably occur in southern Europe and northern Africa, but we should see plenty of shooting stars here in North America. The best times to look for them are the morning hours when the Earth is headed into the swarm. I expect the best showers to occur November 17th and 18th. Don't expect to see a continual flare of meteors like the flares of a major fireworks display. The last really awesome display was a meteor shower Abraham Lincoln viewed as a young man. It was so intense that many people were afraid the world was coming to an end.

If you want to see Mars, Neptune and Uranus, you'll have to set up a telescope at dusk because they will be too low for viewing by 7, 8 and 9PM respectively. Mercury and Pluto are much to close to the Sun for viewing. Mercury has just made an infrequent solar transit (pass across the face of the Sun), and will take a few weeks to climb high enough to be glimpsed in the dawn sky.

The three glorious planets which are capturing all the attention are Jupiter and Saturn which are up all night, and Venus which rises about 3AM. I had my first chance to see Saturn at the maximum power of the new Frosty Drew telescope recently. At more than 800 diameters, Saturn filled the eyepiece view. I've grown accustomed to seeing storm belts on Jupiter, but seeing them in such detail on Saturn is rare.

Leslie Coleman
Author:
Leslie Coleman
Entry Date:
Nov 1, 1999
Published Under:
Leslie Coleman's Columns
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