At least three buzzed by in February.

February was a big month for scientists who study objects in space. Three asteroids flew relatively close to Earth in February. The closest one flew by on February 20th and it came within a million miles of Earth. A million miles might seem like a long ways away, but that’s close enough for astronomers to call these asteroids “near Earth objects.”

An is basically a chunk of rock smaller than a planet, which orbits the Sun. Aster- oid 2000 EM26, which flew by on February 17th, is about the size of three football fields. Asteroid 2006 DP14 flew by on February 10th, and was even bigger; it was about the size of eight football fields. Asteroid 2014 BR57, which flew by on February 20th, is smaller, only about 60 yards across, but it came closest to Earth.

Sometimes an asteroid’s orbit brings it into Earth’s atmosphere. From there, gravity takes over, and causes the asteroid to fall. Luckily, these asteroids usually burn up before they hit Earth. Sometimes a chunk of a large asteroid breaks off and enters the atmosphere. These are called . When a doesn’t burn up completely and some of it hits Earth, it is called a meteorite.

A year ago in February, a meteorite about the size of a house exploded in the atmosphere over Russia. Some pieces of it hit the ground, and more than 1,000 people were injured, but mostly from windows that broke because of the explosion. This was a very rare event, and it was the biggest meteorite to hit Earth in more than 100 years. A huge asteroid may have caused the extinction of the dinosaurs.

Life on our planet changed drastically 65 million years ago when something very big crashed into Earth’s surface. At that time, huge dinosaurs roamed the planet. All but one group of the dinosaurs died out — birds. For a long time scientists wondered what could have caused the dinosaurs to die out. The word for something dying out completely is “ex- tinct.”

In the 1970s, scientists discovered a huge crater in Mexico. After studying the crater, sci- entists said it was probably created when an asteroid crashed into Earth, around the time the dinosaurs disappeared. The crater is more than 110 miles across and 12 miles deep; the asteroid that caused it would have been about 6 miles across.

Many scientists think the impact caused a cloud of dust so large it covered the planet and blocked out the sun. This dust cloud might have cooled the Earth so much that the dino- saurs could not survive. Smaller animals like crocodiles, turtles, and birds, which could find shelter and protection, did survive. Scientists keep track of any object in space that could collide with Earth.

There are thousands of asteroids in our solar system. Most of them are in an area called the . The asteroid belt is located between the orbits of Mars and Jupiter. Sometimes, asteroids knock each other out of the asteroid belt, and get knocked into Earth’s orbit. These are called near-Earth asteroids. Scientists are interested in near- Earth asteroids for many reasons. They believe they can give us information about how our solar system was formed. They think many asteroids may be made of the same kind of rock that forms the inner core of planets.

In 1996, the National Aeronautics and Space Administration, or NASA, decided to study asteroids more closely. In 2000, NASA landed an unmanned spaceship on a near- Earth asteroid. Some scientists think one day we will be able to mine valuable minerals from asteroids.

But scientists are also working to identify any asteroids that could hit Earth. If we can do this, we may be able to knock them off course and avoid getting hit. In 1908, a large asteroid hit an area called Tunguska, in Russia. Nobody was killed, but about 80 million trees were flattened over 770 square miles.