If you look at the
night sky then sometimes you may see what looks like a star flash across and then vanish.
This is a shooting star, or to give it its proper name - a meteor.
Meteors are
very small pieces of rock that are flying round in space. When the Earth
passes through a cloud of these particles as it travels through space the meteors plunge down
through the Earth's atmosphere.
Like space craft the friction between the air and
the meteor makes the rocky lumps very hot. So hot that they catch fire. It is this fiery
shower of sparks that you see as a shooting star.
Most
meteor are so small that they burn up before they hit the ground. However some are much too big
to do this and the remains of these do get to Earth. The remains of these larger objects are called meteorites. Meteorites may have a mass between a few hundred grams and many thouands of kilogrammes.
The larger metoerites do not burn up completely, instead their reamins form craters when they hit the ground, one made the large crater in Arizona in the
USA, and a very large meteorite fell in eastern Siberia in the
early part of the twentieth century destroying a huge area of forest.
The photograph is of the Saarema meteor crater in Estonia which is about 22m deep and almost perfectly circular, with a diameter of about 110 m.There is a very good
museum in Rochouart in central France that shows the effects of the meteorite that fell near
the village a long time ago.
The largest meteorite of all was one that fell onto the Earth many
thousands of years ago, throwing up huge clouds of dust into the atmosphere causing the
planet to cool and probably ending the reign of the dinosaurs.
Astronomers think
that most of the craters on the Moon were made in this way.
If you are patient you
can see meteorites on most nights of the year. The map on this page will tell you where you
may see the most at different times of the year. It is useful to record those that you see on a
map.
