Леониды (english)

Leonids Made Easy What are the Leonids? The Leonids are ameteor shower. They are called the Leonids because they appear to radiate outof the constellation Leo. A Meteor, also known as a shooting star, is a particle from space. Its typical size ranges from that of a grain of sandto that of a pea. A meteor appears when it enters Earth s atmosphere and burnsup high overhead.

Meteors can be seen on any night, but Earth enters clouds ofparticles several times each year and the result is a meteor shower. What Do the LeonidsLook Like? All meteors appearas brief streaks of light moving a short distance across the sky. Some meteorsmove slow and some move fast. Here is a video of a bright, slow meteor. Notethat a streak persisted for a little while after the meteor vanished.

This streak is called the train and is basically a trail of glowing dustleft in the wake of the meteor.The Leonids arefast meteors and they leave lots of trains. They enter Earth s atmospheretraveling at speeds of over 158,000 miles per hour mph . For comparison anIndy race car can reach a top speed of about 250 mph, the fastest jet has a topspeed of 2190 mph, and an orbiting spacecraft has an average speed of 20,000mph.

Besides being fast,the Leonids usually contain a large number of very bright meteors. The trainsof these bright meteors can last from several seconds to several minutes. Where Do theLeonids Come From? Most if not allmeteor showers are produced by comets. In the case of the Leonids the parentcomet is named Tempel-Tuttle and it makes an appearance in our skies every 33years.

Comets are composed of ice and dust. Every time a comet approaches thesun the ice melts and dust is released. Eventually the dust spreads completelyaround a comet s orbit, but most of the dust stays close to the comet. WhenEarth passes through the dense cloud of dust the result is a spectacular meteorshower or a meteor storm. Meteor storms produce several thousand meteors perhour. When Do the LeonidsOccur? Every November17-18 Earth crosses the orbit of comet

Tempel-Tuttle and the Leonids becomevisible. An observer with clear, dark skies can see 10 or 15 Leonid meteorsevery hour on that morning. Unless an observer is living at a very highnorthern latitude generally within the Arctic Circle , the Leonids are onlyvisible during the morning hours. Since Tempel-Tuttlepassed closest to the sun in February of 1998, the years 1998 and 1999 wereexpected to produce very strong displays. During 1998 the Leonids peaked overEurope with hourly rates of 250-300,

while in 1999 astronomers are predictingan even better display over western Europe and the Atlantic. During themornings of November 17 and 18 observers anywhere in the Northern Hemisphereshould see greater than normal displays. Start watching sometime after about11 30 p.m. local time because of Earth s rotation, local time literally means your time .

The radiant will still be about an hour from rising,but you will have the opportunity to see the Grazers . These areLeonids that are not dropping down into Earth s atmosphere, but are insteadgrazing the atmosphere. These appear as reddish meteors that advance from eastto west across a large part of the sky. In 1998 there were reports that severaleast coast television stations were receiving calls that rockets

were seencrossing the sky. These rockets were in fact the Leonid grazers. Asthe radiant rises near 12 30 a.m. local time, the Leonids will travel shorterdistances across the sky as they drop down into the atmosphere. Their colorwill also change to white and blue-white. Some of the brightest will actuallyappear slightly greenish.

As the morning progresses, meteor rates shouldgenerally increase. Keep watching until morning twilight begins. How Do You Observethe Leonids? The point fromwhere the Leonid meteors appear to radiate is located within the constellationLeo and is referred to as the radiant. The radiant is located in the westernportion of that constellation in what is commonly referred to

as the sickle or backwards question mark. The radiant locationwith respect to the horizon is shown below. Image produced bythe Author using Starry Night 2.0 and Adobe Photoshop 5.0. It represents theview from mid-northern latitudes at about 3 00 a.m. local time. To best observe theLeonids wear appropriate clothing for the weather. Lie outside in a reclininglawn chair with your feet pointing towards the east the general direction

ofthe radiant . Do not look directly at the radiant, but at the area above andaround it. The Leonids can be observed into morning twilight. Other minor meteorshowers will be going on at the time and stray meteors, more commonly calledsporadics, will frequently be seen that do not belong to a meteor shower. Whenyou see a meteor mentally trace it backwards and if you arrive at the sickle of

Leo it is probably a Leonid.