Leonid meteor shower peaks Saturday night Nov. 17-18, 2007

William Atkins
Sunday, 18 November 2007 00:07

Science - Space

The Leonid meteor shower, the Leonids, will be peaking Saturday night in the east-northeastern sky as the atmosphere of the Earth strikes debris in the tail of Comet Tempel-Tuttle.      

Whether the peak will be bright or dull depends on the amount of dust and debris that impinges on the Earth’s atmosphere.

Whatever happens, the meteor shower will probably not be as dramatic as its occurrence in 1833 when reportedly one to two hundred thousand meteors (sometimes called shooting stars) were seen per hour at its peak.

Between 1999 and 2002, the meteor shower contained up to one thousand meteors per hour.

In 2007, however, astronomers are predicting that about ten to fifteen meteors will appear in the night sky per hour; however, this number is just an estimate so it could be less or more.

The Leonids meteor shower is named because the meteors appear to stream out of the constellation Leo. It is expected to peak sometime around 11 p.m. EST Saturday, give or take about an hour according to the NASA Leonid Multi-Instrument Aircraft Campaign. The display is expected only to last about two hours.

Although only about a dozen meteors per hour should occur at this peak, the Moon will have already set so it should be a very dark sky and, hopefully, clear of clouds.

To find the more specific area of the east-northeastern sky that the Leonids meteors will come from, find the Big Dipper. Then, look for the bottom of the Big Dipper’s cup. Next, scan the sky to the east of the cup’s bottom to the star Regulus, which should be close to the horizon.

The Tempel-Tuttle comet has a 33-year orbit about the Sun, which goes out as far as the orbit of the planet Uranus. The debris from the comet travels at about 44 miles per second (71 kilometers per second) through Earth’s atmosphere. The meteors should be seen in the sky for a few seconds before being destroyed in the atmosphere. (When the meteors are outside of Earth's atmosphere, and are in outer space, the objects are called meteoroids.)

The main source of light of a meteor seen by observers on Earth is caused by the air molecules slamming into the meteoroid. They, then, fragment the dust, and the resulting stream of tiny debris collides with individual atoms of Earth's atmosphere, which then cool down by glowing visibly to whomever is looking at them.

NASA has a website that predicts the peak of the Leonids meteor shower for your regional area. Go to http://leonid.arc.nasa.gov/estimator.html.