Planet Earth has visitors!

It was like a scene from a science fiction movie on the morning of February 15 in Chelyabinsk, a city in Russia near the border of Europe and Asia. People saw a bright object flying through the sky, leaving a white trail, and then exploding with a bang and a flash.  The explosion released a very large amount of energy which shattered windows in over 4,000 buildings in nearby areas. Over 1,000 people were injured mainly because of the glass flying around from the broken windows. The object was a meteor about 55 feet (17 meters) in diameter (which is about 3 medium-sized cars lined up) when it entered Earth’s atmosphere.  After the explosion in mid-air, smaller pieces of the meteor fell to the ground.  People in the area have been busy looking for these meteorites. Some have been trying to sell the meteorites on the Internet. This was the largest meteor to have been reported since 1908, when a meteor had blown up over Siberia, also in Russia, destroying an estimated 80 million trees.

While all this was happening, many scientists around the world were paying attention to another object from space that was also headed our way. On February 15, about 16 hours after the meteor exploded over Russia, an asteroid named 2012 DA14 flew by just 17,150 miles (27,600 kilometers) above Earth’s surface. That seems quite far, but that is closer to our planet’s surface than some of the weather satellites we have orbiting around Earth! 2012 DA14 zoomed by at 4.8 miles per second (7.82 kilometers per second).  It is three times the size of the meteor that made it to Russia, and scientists say that the two events were unrelated. The meteor over Russia took scientists by surprise, but in contrast, scientists had been studying the flight of 2012 DA14 for some time.

We’ve mentioned the words asteroids, meteors, and meteorites. What are the differences? Asteroids are rocky bodies that orbit our sun. Their sizes vary – they can be less than one kilometer (about half a mile) in width, or can go up to almost a thousand kilometers (about 600 miles). If the rocky body is very large, it starts getting into the “dwarf planet” category. Once an asteroid enters Earth’s atmosphere, it is called a meteor. Once a meteor lands on Earth’s surface, it is called a meteorite. Many meteors burn up as they pass through the Earth’s atmosphere.

There are thousands of asteroids that fly by close to Earth (referred to as “near-Earth asteroids”). An asteroid is defined as “near-Earth” if it comes within 1.3 astronomical units of the sun, where one astronomical unit is the average distance from Earth to the Sun -150 million km (93 million miles).

Here are videos about the two events.

 

 

Did you know?

The first asteroid that was discovered was in 1801 by Giuseppe Piazzi. It was given the name Ceres, and has been since reclassified as a “dwarf planet”.

Did you know?

Scientists believe that  65 million years ago, a space rock about 15km (9 miles) wide hit what is now called the Yucatan Peninsula in Mexico, wiping out the dinosaurs.

Image Credits: Nikita Plekhanov for Russia’s meteor’s image; NASA/JPL-Caltech  for 2012 DA14’s image