Something happened this month that you probably weren't even aware of. Astronomers working at the Siding Spring Observatory in New South Wells, Australia spied an asteroid in the skies on June 10. That asteroid was originally estimated to be 500 m or 0.31 miles wide. The shocking part of the discovery is that on the cosmic scale the asteroid was going to pass fairly close to Earth.
The asteroid only came 3.4 million miles away from the planet, which in reality is a very long way away. The truly disturbing part for some scientists was no one even knew the asteroid was there until four days before it passed the earth. Had the asteroid actually been on a collision course with our planet, four days wouldn't give time to respond.
To add insult to injury, once the asteroid was closer to earth it was discovered that it was almost twice as large as previously believed at 0.62 miles wide. Scientists say the reason the size observations were so off was because the surface of the asteroid was very dark and didn't reflect light. The reason the asteroid went unobserved until it was so close to our planet had to do with the fact that it was detected in the southern hemisphere skies were we have a few asteroid watching programs.