April 1, 2013
Earth is experiencing an unusual cosmic bombardment as four large asteroids pass it in just one day. Fortunately astronomers don’t seem to joking when saying none are expected to pose danger.
The largest is 4034 Vishnu, which is 800 meters across – the length of the Burj Khalifa in Dubai – though much greater in mass. In comparison, the Tunguska meteorite that devastated hundreds of miles of Siberian wilderness when it landed in 1908 was estimated to be no bigger than 100 meters. The asteroid that may have led to the extinction of dinosaurs 65 million years ago may have been up to 10 kilometers across.
But 4034 Vushnu – which was discovered in 1986 – will pass nearly 23 million kilometers from the Earth’s surface. The closest of the four, EN 89, will be just over 5 million kilometers away from the planet. The asteroid was only discovered a fortnight ago.
Although in everyday terms, the asteroids, ancient cosmic bodies that did not form into planets, will be a distance away, they are still classed as Close Approaches by astronomers. In total several hundred of them happen each year, but it is unusual for so many passes to happen over the course of one day.