Measuring between 72-160 feet wide, newly discovered Near-Earth Asteroid 2012 XE54 recently came within 141,00 miles of Earth.
As Steve Tracton in the Washington Post reports:
Small asteroids such as these are difficult to discover, usually detected within a week of their closest encounter, and that’s much too little time to do anything but issue a warning about the likely locations of impact. In most, but not all cases, impacts would focus on oceans or relatively unpopulated regions.
Fortunately, asteroid strikes by ones of the size that wiped out dinosaurs are few and far between. An impact with more common intermediate-sized asteroids – dimensions larger than about 500 feet – would explode with the power of a large atomic bomb. However, large and intermediate-sized asteroids can be detected and tracked years before any close encounter with Earth.
At this time, there are no sure collisions on the horizon even over the next few hundred years. That said, much of the sky, especially that viewed from the southern hemisphere, is not being monitored!
I asked Sentinel Mission Director, Harold Reitsema to share some of his thoughts on XE54. He writes:
“The close approach of asteroid 2012 XE54 is not an unusual event: indeed, close passes within the orbit of the Moon happen several times a month. These are usually quite small objects that are too faint to be discovered by ground-based observatories until they are within a few days or weeks of their Earth flyby. While discovery with that kind of lead time would permit evacuation of the impact zone to preserve life, physical property damage could be quite severe.
The B612 Foundation is developing a space telescope that will give decades of warning about future close encounters. With that much time, a space mission can be built to deflect the asteroid and eliminate the possibility of future impacts by near-Earth asteroids.”