At approximately 6:28 EST tonight, a 1,300-foot-wide (400m) asteroid will make its closest pass by Earth. Zooming 201,700 miles (321,867 km) above Earth's surface at its closest approach, asteroid 2005 YU55 will cruise within the moon’s orbit for the entire evening.
Luckily for us, the asteroid will fly by without incident. An impact from this asteroid, however, could be devastating. For instance, in 1908, scientists believe that an asteroid or comet detonated above Siberia, demolishing 80 million trees across an area of 2,150 square kilometers (830 square miles). Known as the Tunguska event, the asteroid detonated with an energy equivalent to 10-15 megatons of TNT, 1,000 times more powerful than the atomic bomb dropped on Hiroshima. On top of that, the Tunguska asteroid was likely 4 to 8 times smaller than 2005 YU55.
It’s been over 30 years since such a large object has come so close to our planet, and scientists don’t expect another approach from a comparable asteroid until 2028. If you want to catch a glimpse of the asteroid for yourself, you’ll need a telescope with at least a 15-centimeter (6-inch) aperture. For more detailed information on how to spot the asteroid at home, check out Sky and Telescope’s guide. NASA has provided an image of the asteroid’s trajectory, as seen below.
Researchers have been studying 2005 YU55 since its discovery 6 years ago. So far, scientists know that the comet is darker than charcoal and approximately spherical but hope to discover more after tonight. With this flyby, astronomers hope to garner detailed images of the asteroid by bouncing radio waves off of its surface. For updates on NASA’s efforts to detect and track potentially dangerous Near-Earth Objects, click here.