We’re in for another meteor treat this time of year: the famous Leonid Meteor shower peaks in mid-November, around the 17th-18th. These showers are caused from Earth passing through a trail of dust emitted by a small comet more than four centuries ago.
Cosmic Garbage to Light Up the Night
The Leonids are caused by cosmic garbage. That may not sound good, but it should make for a good sky show. The meteors are produced by particles that are shed from the Comet Tempel-Tuttle every time it passes close to the Sun during its approximately 33-year orbital journey. Trailing behind the comet is a dirty trail of very small dust particles, generally less than 1 millimeter in size and orbiting the Sun. As the particles run into the Earth’s atmosphere they vaporize within a few seconds at altitudes of about 60 miles above our heads.
The showers peak between roughly midnight and 5:30 a.m. local time on November 18th as the Earth makes a 400,000-mile journey through a cloud of particles that was ejected from the nucleus of Comet Tempel-Tuttle back in the year 1567.
Larger particles, up to pebble-size, can produce brilliant meteors known as fireballs, rivaling in luminosity the brightest stars and planets and on rare occasions, even the Moon. Leonids travel at very high speeds through our atmosphere–up to 162,000 miles per hour–and some can leave bright trails of ionized atoms producing trains that can last for many seconds, or even minutes.
The mornings before and after peak may also produce some visible meteors as well.
The Leonid radiant (the perspective point from which all the meteors would appear to originate) is within the so-called Sickle of Leo; a backwards question-mark pattern of stars that outlines the head and mane of the constellation Leo, the Lion (the brightest star in the constellation, Regulus, makes up the dot of the question mark). Hence the meteors are known as Leonids. Observers all across North America may experience a good Leonid show with meteors flashing out every few minutes. The Leonids produce an average of 20 to 30 meteors per hour, but it can vary from year to year.
In order to see meteors, the sky must be clear and your selected observing site should preferentially be free of light pollution; the less light, the more meteors will be seen! Notice that Leonid meteors occur in the after-midnight hours. Hence, there is no point in starting your observation much earlier. Be very aware that it can be very cold in mid-November, so be sure to wear several layers of warm clothing.
For comfortable observing, use a reclining chair and place yourself either in a suitable sleeping bag or under several blankets. While observing, do not fix a particular star, but scan the area of sky from the north-west to east. Look patiently across a wide area of sky and wait for a shooting star to appear.
Old chronicles contain references to past Leonid meteor storms back to the 10th century A.D. The best-known Leonid meteor storms are those of 1833 and 1966, when literally tens of thousands of meteors darted across the skies during the peak hour! The 1833 meteor storm was so spectacular that it in fact launched meteor research as a branch of astronomy.
Update for 2015: Unfortunately, we won’t see a meteor storm this year, but with Leonids appearing at an average of every two or three minutes, a very entertaining meteor display is anticipated.
Good Luck and Clear Skies!