Big Rock

From CNN:

On the other hand, go ahead and look. As it misses Earth by about 300,000 miles (slightly farther away than the moon), the asteroid, named 2015 TB145, will be visible to those with good telescopes -- and NASA, which announced the discovery.

Calling it "one of the best radar targets of the year," a Jet Propulsion Laboratory report on the asteroid said that "the flyby presents a truly outstanding scientific opportunity to study the physical properties of this object." 

The asteroid will be traveling through Orion on October 30-31.

It's a good thing it will miss, though. The asteroid is estimated to be 300 to 600 meters wide and traveling at 78,000 mph. By comparison, the meteorite that exploded in the sky over Chelyabinsk, Russia, in 2013 was about 20 meters wide.

Remember KE=1/2mv^2.  You think .45 ACP and .40S&W qualify as major calibers--they are wimpy by comparison.