Last modified: Wednesday, November 6, 2002
STAR TRAK/November 2002
Leonid meteor shower predicted to be storm
A meteor shower is to a meteor storm as a sprinkle is to a cloudburst.
The annual Leonid meteor shower will peak on the night of Nov. 18-19. If the predictions of meteor specialists hold up, there will be a meteor storm in some locations that will be well worth getting up early to see. For those who miss this opportunity, the next one won't come for about 30 years.
Several thousand meteors may streak overhead for two hours or so for observers fortunate enough to be in the right place with a clear sky. The moon will be full, so fainter meteors will be washed out, but there will be more than enough bright meteors to create an unforgettable spectacle.
According to scientists who have studied the past behavior of the Leonid meteors, there will be two periods of intense meteor activity. People watching throughout North and Central America should see a burst lasting perhaps two hours in the predawn hours of Nov. 19, with a predicted peak around 5:30 a.m. EST (10:30 Universal Time).
For viewers in Europe and much of Africa, a cascade of meteors should occur at about 11:00 p.m. EST on Nov. 18 (4:00 Universal Time on Nov. 19).
Maps showing which parts of Earth's surface will be able to see the predicted peaks are at http://skyandtelescope.com/observing/objects/meteors/article_719_3.asp.
The Leonid meteors, so named because they appear to radiate from the constellation Leo the Lion, are caused by streams of fast-moving dust particles from Comet Tempel-Tuttle, which rounds the sun every 33 years.
Meteor watchers have been anticipating the Leonids since 1999, when the Leonid shower turned out to be a meteor storm for observers in southern Europe and northern Africa. In most years the Leonids are a minor shower, but every 33 years or so, they are capable of producing a spectacular meteor storm with a thousand or more meteors per hour.
There was a Leonid storm on Nov. 17, 1966 (also not visible in most of the United States), so the meteor storm of 1999 continued the 33-year pattern. But in 1999, for the first time in history, a team of astronomers successfully predicted the exact time of the Leonid storm, missing by only a few minutes instead of by hours as previous estimates always had done. They did it by tracing specific paths of debris left behind in space during different passes of the Leonids' parent comet, Tempel-Tuttle.
Most meteor showers happen when Earth crosses the orbit of a comet. The meteors are caused by tiny particles of dust and other debris that were released from the comet's nucleus and left behind in space as the comet got closer to the sun. As Earth plows through this stream of particles, each one collides with our upper atmosphere at tremendous speed and burns up almost instantly from friction with air molecules. The resulting heat momentarily creates a streak of glowing air molecules that we see as a meteor (sometimes called a "shooting star" or "falling star").
Understanding of the Leonid meteor shower has greatly improved during the past two years, and astronomers have made specific predictions for the 2002 Leonids. They have calculated that this year Earth will pass through two trails of cometary debris left during the 1767 and 1866 passages of Comet Tempel-Tuttle, which should result in two separate bursts of meteors.
Watch for meteors after midnight local time on the night of Nov. 18-19 as the constellation Leo gets higher in the east. That is when your part of the planet will be rotating into the path of the oncoming meteors. The higher Leo is above the horizon, the more meteors will appear all over the sky. The bright star Regulus is part of Leo and can serve as a marker for the Leonids.
Light pollution wipes out many meteors for observers, so choose a dark site with an open view of as much of the sky as possible. Face eastward and give your eyes at least 15 minutes to adjust to the dark. A lawn chair and blanket will help you stay comfortable as you watch the sky.
More information about meteor showers is available from the American Meteor Society at http://www.amsmeteors.org/showers.html.
Saturn will rise in the early evening in November and be visible for most of the night. For a few hours, at least, its bright yellow light will outshine every other object in the sky, dominating the constellation Taurus the Bull and easily outshining its brightest star, orange Aldebaran. Saturn's rings will be a fascinating sight in a telescope when the planet is high in the sky.
Then Jupiter will rise nearly four hours later, and Saturn will have to yield to the even brighter white giant. Appearing at 11:30 p.m. local time at the beginning of the month and at 9:30 p.m. by month's end, Jupiter will be highest in the south around the start of morning twilight.
Venus will complete its passage between Earth and the sun and come into view low in the east-southeast during morning twilight in early November. It will brighten rapidly and increase in altitude as the month advances, rising an hour before the sun by the second week and three hours before the sun as the month ends.
As Venus rushes upward, it will close in on Mars, which will rise two to three hours before the sun. Looking pale orange in comparison with brilliant white Venus, Mars will at least manage to stay above its glamorous companion. Even the bright white star Spica will be twice as bright as Mars when it passes close by the planet on Nov. 22.
Mercury will be too close to the sun to be seen during November.
The moon will be new on Nov. 4, at first quarter on Nov. 11, full on Nov. 20 and at third quarter on Nov. 27.