Most people see the sky above as a symbol of peace and tranquility. But what if someone told you out there a massive rock, big enough to whipe out the entire human race, was heading towards Earth?
Billion years ago planet Earth was bombarded with thousands of small and larger rocks. The solar system was beginning to form.
Erosion erased all visible evidence of this bombardment. But when you look to our neighbour, the moon, you see the many impacts our planet too must have had.
Where do these rocks come from?
Between the orbit of Mars and Jupiter thousands, maybe even billions of rocks, some of the size of several kilometers, move around. They rotate, bounce onto each other in their orbit around the sun. Their orbits show a chaotic pattern, as these orbits are influenced by Mars, Jupiter and the other planets.
Further away into the depth of the universe you'll find the 'Oort-cloud', a very large area with an unknown amount of gigant iceballs and solid rocks. This Oort-cloud is so big, that it can be influenced by our nearby stars.
Sometimes the orbit of a rock, or asteroid, is influenced in such a way, that the rock leaves its position, and begin wandering through the solar system. Attracted by the gravity-force of the Sun, it is bound to enter the center of the solar-system, where our planet Earth is as well.
Most of us have seen a comet sometimes in their lives, as faint far-away snowballs, hardly seeable with the naked eye. But what if such an object would collide with the Earth?
Are these objects rare and will they pass Earth only once in every ten years or so?
If rocks with the size of 10 meters or more would shine like a star, you would see about a 100 million lights on a cloudless night in the sky. That would be a most terrifying sight, wouldn't it be!
A rock with the size of 100 meters would cause a disaster. Any bigger it would cause a catastrophe and if would certainly threathen human life on Earth.
Well, astronomers watch the sky, so if anything would come this way, we would know, won't we?
The problem is that astronomical speaking these rocks are very small and hardly if not visible through a telescope. Yet the size would be deadly if such a rock entered the atmosphere and collided with Earth.
An Arizona-based Spacewatch program has started to track all 'near-earth asteroids' that could be of danger to us. And because of the chaotic way the orbits of these things behave, calculation of their orbits is never 100% correct.
11 March 1998 an astroid (1997 XF11) was discovered that will pass Earth 30,000 miles - about one-tenth as far as the Moon! This is an estimate, it could be wrong for 180,000 miles!
"The chance of an actual collision is small, but one is not entirely out of the question," according to a notice filed by the International Astronomical Union.
"It has enormous destructive potential," said Steven Maran of the American Astronomical Society, but he added it will take several more years of observations before experts are certain of its path.
This asteroid is not the only one of its kind. Already more than 108 objects in space are considered to be potentially danger for planet Earth.
The asteroid will make its closest approach to Earth on 26 October 2028. It will become more visible in 2000. In 2002 it will pass for the first time within 6 million miles on Halloween Eve.
This asteroid is a mile in diameter. An asteroid 6 to 10 miles across was probably the cause of the extinction of the dinosaurs 65 million years ago.