Catch a falling star
2003-05-08 13:22
Paris - The extraordinary find of a meteorite that was photographed as it plummeted to earth has helped resolve some of the mysteries about the solar system's rocky wanderers - but also created new ones.
The shooting star was photographed on April 6, 2002, by a time-lapse camera set up in southern Germany by the European Fireball Network, a group of meteor-crazed astronomers.
The picture revealed a 91 kilometre trail, blazed by the rock as it entered the earth's atmosphere after a journey through space that lasted millions of years.
Less than three months later, on July 14, 2002, there came an amazing discovery - a 1.75-kilo chunk of the debris was found near the fairytale, turreted castle of Neuschwanstein, in Bavaria.
It was only the fourth time that meteorites have been recovered from detected meteors, despite the sky-scrutinising efforts of the European Fireball Network and others around the world.
Two sources
There are two big sources of meteors. Most them come from debris deposited by comets, whose icy heads start to melt as they race closer to the sun in their course around the solar system.
The other source is asteroids, the primitive rubble left over from the creation of the solar system. They orbit the sun, mostly in a belt located between Mars and Jupiter.
These rocks sometimes bump and jostle, which forces them into a new trajectory, or their orbit is deflected by the gravitational pull of a planet, and in this way they may then cross the sarth's path.
As the space rocks hit the atmosphere, they are enveloped in a reddish-golden ball of fire. If any of the meteor's debris survives, it is called a meteorite.
In a study to be published on Thursday in British journal Nature, astronomers led by Pavel Spurny of the Czech Republic's Academy of Sciences, calculate the Neuschwanstein meteorite's trajectory and estimate its age, on the basis of its exposure to the cosmic rays of deep space.
Begin to understand our solar system
Neuschwanstein, the astronomers were startled to find, came from the same "meteor stream" as the first of the four historic space rocks - a 4.5 kilo chunk found in 1959 in Pribram, in what was then Czechoslovakia.
But Neuschwanstein is much older than Pribram - it spent 48 million years in space, as compared to a paltry 12 million years - and has a quite different chemical composition.
It has less iron oxide, magnesium, silicon and calcium among its key elements and is more granular.
If Neuschwanstein came from an asteroid, the evidence challenges assumptions that the solar system's building rubble comprises a boringly similar chemical mass.
"It seems the meteor stream in which these objects were flowing is more heterogeneous than is usual supposed," said Jack Drummond, of the Starfire Optical Range in New Mexico.
"Looking skyward, knowing where these rocks came from, we may begin to understand something of the early history of our solar system."