Asteroids!

Recently, we've had a lot of astrological happenings here on planet Earth. First a sizable asteroid entered the atmosphere measuring in at 55 feet across and 10,000 tons. This meteor, traveling at a speed relative to earth at 40,000 mph exploded high altitude with the energy of about 500 kilotons of dynamite. To put that force into perspective the nuclear bomb dropped on Hiroshima had a force of about 15 kilotons. The high altitude spared Earthlings of significant damage, but the shockwave broke glass over about a 50 acre range injuring about 1200 people.

Here is some amazing footage of the meteor exploding:

Just a few hours later an unrelated asteroid named DA14 narrowly missed earth. This one was much, much larger measuring 150 feet across and weighing 130,000 tons. Where the Russian meteor was about the size of a schoolbus, DA14 is the size of the white house. DA14 would have exploded with 3.3 MEGATONS of energy. Interestingly, while doing some research I found out that we were actually struck by a meteor about the size of DA14 in 1908. It struck in an unpopulated location in Siberia called Tunguska. When it popped, the explosion knocked trees down for 830 miles! The devastation of a DA14 sized asteroid in a populated city would be incalculable.

Tunguska damage:

DA14 will miss us by about 17,000 miles. Astronomically speaking, it's unbelievably close. Here's how to put that into Earth-term perspective. The moon is 221,000 miles away and Earth is about 7900 miles across. This asteroid will actually come INSIDE our geosynchronous ring of satellites. It's about 1/10th the distance to the moon. About 1/5500th the distance to the sun.

If that still sounds far I'll try to put it into astronomical terms. Andromeda, the NEAREST spiral galaxy to us is 15,000,000,000,000,000,000 miles away. I don't even know what that number is, but it's 2.5 million lightyears x 6 trillion (miles in a lightyear). DA14 is 1/882,352,941,176,470 the distance to Andromeda, and that is the CLOSEST spiral galaxy. Andromeda is about 765,000 parsecs away. This distance is pretty much impossible to illustrate because you need something for size comparison. The biggest thing you and I know is the earth and on pretty much any scale we could imagine, earth would have to be microscopic to see Andromeda and the milky way at the same time. This website did the best job I've seen so far: http://scaleofuniverse.com/

To minimize the scale here, the nearest solar system to us, Alpha Centauri is 4.21 lightyears away. The asteroid is 1/10th of a lightsecond away from us. It's so close to use that our gravity changed it's course by nearly 90 degrees.

One other thing I wanted to do is explain the difference between an asteroid and a meteor. An asteroid is a relatively small bodies orbiting the sun. Asteroids are generally rock and/or metal. I think that science has actually further classified asteroids into some boring sciency names like small-planetoids etc, but I'm not too sure. When space stuff collides, small particles are chunked off and called meteoroids. When one of these enters the atmosphere, it starts burning up and leaves a tail. This is called a meteor or shooting star. Finally, if a meteor survives the atmosphere and collides with the Earth's surface, it's called a meteorite.