Friday, February 15th, will go down in the record books as one of the busiest celestial days in recent history. First came the unexpected meteor explosion in Russia and then, Earth's closest encounter with an asteroid yet!

The excitement began early in the morning when the startled citizens of Chelyabinsk in Western Siberia witnessed a blinding flash followed by a booming shockwave in the skies. Before anybody could react, a meteor estimated to be the force of 20 atomic bombs exploded, shaking and impacting an area of over one million square feet and damaging over 3000 buildings.

Besides creating massive panic amongst the city's 1.1 million residents the explosion also resulted in over 1,000 injuries. Fortunately, most of them were minor cuts and injuries caused by the flying glass debris. Some meteorite fragments also ended up in a frozen reservoir outside the town, leaving a 26-foot crater in the ice.

The scientists at NASA and the Russian Academy of Sciences estimate that the meteor was roughly the size of a bus and weighed between 7,000 to 10,000 tons. It entered the Earth's atmosphere at a supersonic speed of between 33,000 to 40,000 mph and exploded 12-15 miles high, releasing 300-500 kilotons of energy that resulted in a 300-mile long trail.

Though scary, these kind of explosions are what scientists are call a once in a century event, because most meteors dissipate when they come in contact with the earth's atmosphere. According to the experts at NASA, Friday's meteor was the largest to hit earth since the 1908 Tunguska event when an asteroid explosion leveled over 80 million trees in a remote region of Siberia.

What was a little strange about this meteor explosion was that it occurred a few hours prior to the flyby of the 150-foot DA14 asteroid that zipped within 17,200 miles of Earth. While the timing may seem as though the two events were related, the experts at the European Space Agency maintain that this was just a cosmic coincidence. Whether that was truly the case or not, Friday sure was a busy day for our space debris.

So what is the difference between asteroids, meteoroids, meteors and meteorites? Not much! They are essentially all space rocks just labeled differently. An asteroid is usually defined as a space rock that is between 1-10 meters wide (3.3 -33 feet) - Anything smaller than that is dubbed a meteoroid. A meteor is an asteroid that burns up as it enters the Earth's atmosphere and a meteorite is one that actually manages to survive through it and land, like the one in Russia on Friday!