Updated calculations state: the chance of a fatal impact is one in 5,000 and not in 1,500; an asteroid up to a kilometer in diameter will cause heavy environmental damage; If we meet an asteroid with a diameter of 10 kilometers, this could lead to the end of life on Earth.
Tamara Traubman, Haaretz
One of the questions that has troubled astronomers in recent years is what is the chance that an asteroid will collide with the Earth. Recent calculations show that the probability of such a catastrophic collision is even smaller than they thought: in the next hundred years, the chance that a large asteroid will collide with the Earth is one in 5,000 and not one in 1,500 as assumed until now. These findings were reported in the current issue of the scientific journal "Journal Astronomical".
The findings are based on data collected in a project known as the "Living Room Sky Survey". In this project, researchers from universities in the United States and Japan mapped large parts of the sky, using a telescope located at the Apache Point Observatory in the United States.
The new data obtained from the sky survey allows astronomers to estimate the size of asteroids with improved accuracy. Dr. Zlejko Ivcik, an astronomer from Princeton University who headed the study, explained that in order to estimate the size of the asteroid, one must know its composition.
Earth's atmosphere protects it from most asteroids that are less than 50 meters in diameter. The impact of an asteroid up to a kilometer in diameter would cause a disaster on a local scale. An asteroid with a diameter of about two kilometers would cause severe environmental damage on a global scale. Such an impact would probably cause the earth to be covered in asteroid particles, which could cause crop destruction, famine and disease.
Huge asteroids - with a diameter of 15-10 kilometers - will wipe out the human race and many other species from the surface of the earth. Scientists believe that the extinction of the dinosaurs, which happened about 65 million years ago, was caused by an asteroid collision of such a diameter. The researchers' estimates were exaggerated. Ivcik and his colleagues discovered that the solar system contains about 700 asteroids that are about one kilometer in diameter. According to him, the new estimate is three times smaller than the previous estimated number of asteroids, which was about two million.
According to Ivcik, in previous studies the researchers were only able to locate asteroids with a diameter of five kilometers or more, and from the number of these asteroids the researchers deduced the number of the smaller asteroids. But as it became clear from the sky survey data, the researchers' estimates were exaggerated. Now that researchers have been able to spot the small asteroids,
Realized that they are not as many as they thought. "It is still not clear why the number of asteroids is lower than predicted," says Ivcik, "but the answer to this question will provide important information about the history of the solar system, and the factors that shaped the asteroids. Despite the new data, there remains a lot of uncertainty, but this is still the best information we have", he concluded.
