Astronomy Online

The Leonids

[NB! More information about the Leonids in 1999 may now be found at the dedicated site on the ESO web http://www.eso.org/outreach/info-events/leonids99/].

Here is a joint project which does not require much technology - but which may give an astronomical experience for lifetime.

What is a meteor shower ?

As a comet enters the inner Solar system - parts of it will evaporate. During this evaporation smaller and larger fragments - from the tiniest dust particles and to large rocks - will spread out into a meteoritic stream: a loose collection of this material that continues to circle the Sun, more or less along the comet's original orbit.

In case our planet Earth passes through such a meteoritic stream - that is when the orbits of the Earth and the comet nearly intersect in space - we will experience what is called a meteor shower. This happens quite regularly - but right now, in the middle of November - amateur astronomers across the world look forward to one particular event - referred to as the Leonids. The name refers to the fact that most of the meteors seem to come from the direction of the constellation of Leo (The Lion).

More information about all of this is available in a number of very interesting articles:

"The Leonids' Last Hurrah?" Sky & Telescope - Nov. 1996.

"The Leonids: King of the Meteor Showers" Sky & Telescope - Nov. 1995.

By the way, did you know the difference between the following words:

Meteoroid: a small, rocky body, moving in the Solar System (the size is from a few millimetres up to a few metres across; if it much larger, it will be refered to as an Asteroid or a Minor Planet.

Meteor: the light phenomenon (shooting star) that may be seen when a meteoroid enters into the Earth atmosphere and burns because of the friction with the molecules in the air.

Meteorite: the piece of `rock' which you may collect on the surface of the Earth, if (parts of) the meteoroid survives the fall through the atmosphere intact. Meteorites weighing up to many tons may be seen in the world's museums.

Do you want to know about meteorites? This site has much interesting information. And there are more intersting links at the end of this text!

Earlier observations of the The Leonids

We strongly suggest that participants in Astronomy On-Line join this international network of observers!

Usually the Leonid meteor shower is not particularly intense - only 10-15 meteors pr hour. However, they have the potential of giving a real meteor storm.

History shows the Leonids have a dramatic peak with approximately 33 years of periodicity. Huge meteor storms were seen in 1799, 1833 and 1866. The meteor storm of 1799 was seen from Europe and South America and the famous German discoverer Alexander Humboldt wrote from Chile.

The night between November 11 and 12 was calm and beautiful.... During 4 hours we observed thousands of huge fireballs, often with a brightness like Jupiter. Long smoketrails were left behind, lasting 7-8 seconds, often the meteors exploded leaving trails too.

In the following years the Leonid meteor storm vanished, but during 1831, 1832 and 1833 the storm regained its strength. In 1832, on the night between November 12 and 13, huge meteor streams were observed above France, Holland, Switzerland and Russia. One observer in Boston counted 8660 meteors during 15 minutes.

On the night of November 12-13 in 1833 probably the most dramatic meteor storm ever appeared. Huge displays were observed above the USA; during the 3 hours of maximum people fainted, believing the world would end, and that sunrise would be the start of Doomsday.

Press expectations were high during the November nights of the next maxima, in 1899 and 1933. However, on these occasions the official count rates were disappointingly low. Similar to the 1992 Perseid disappointment, public attention to astronomy experienced a major setback.

The most recent storm which took place on November 17, 1966 and it was a complete surprise. Astonished observers in the USA could record a peak of 25 000 meteors during 15 minutes.

So, remembering the years of 1831-1833, and 1966, these meteor showers deserve out attention. However, when addressing the press, please notify that it is always risky to give any predictions. But be sure, as one of the veteran observers told us: "IF the peak arrives, it will be an experience for your lifetime".

From Erik Arnesen, Oslo: A Critical Look at our Godless Society - Note that some of the observers are fainting- believing Doomsday was near! (1913)

How to observe The Leonids in November 1996

Quoting from:

Sky Online meteor page:

"When watching even the best annual showers, however, you need to be patient. You might see one meteor every minute or two on average. And that's under ideal, dark-sky conditions with no moonlight or artificial light pollution. Any skyglow dramatically cuts down the number you'll see.

Most meteor showers are active between midnight and dawn. The later you watch after midnight, the better. Bundle up against the cold, bring a reclining lawn chair, and find a dark site with a wide-open view of the sky. Lie back, relax, and gaze up at the stars.

How many meteors can you count in an hour? "

The peak itself may climb up to 40 meteors pr second. Maximum is expected around Nov. 16-17.

European Observers may even have the best position. Last minute details - reports etc. may be found in the Sky & Telescope Weekly Electronic News Bulletin as well as - of course - the Astronomy On Line Newspaper .

When preparing your observings, do not forget warm clothing - maybe some hot chocolate - etc. The lawn chair is most recommendable - but MOST important - turn ALL LIGHTS off - stay away from any light sources. After a while - your eyes will adapt to darkness, giving you the beauty of a real moonless sky.

Please report the following data:

Report your data as soon as possible to the EAAE European Student Group via Anders Västerberg (Sweden) or Mogens Winther (Denmark).

More information

Previous student meteor photos, advices how to photograph meteors - how to identify a genuine meteorite - see the article Meteorites and Fireballs from the EAAE Newsletter. This article also contains a number of important links to other sites with information about these subjects.

If you are an experienced observer, you may want to see the page with information about expert observations.

This project was prepared by the European Student Project Group of the European Association for Astronomy Education (EAAE):


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