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.