Just how frequently do meteors hit Earth?

How often is Earth hit by meteors from space?

For technicality’s sake, a meteor is just a piece of an asteroid or comet that has entered Earth’s atmosphere. Before arriving at the atmosphere, these pieces are called meteoroids. Thousands of small rock fragments enter the atmosphere every year, and most of the debris is burned up on its decent to Earth, leaving a bright trail in the sky.

The only two largest recorded meteor “impacts” on Earth were the 1908 Tunguska event and the 2013 Chelyabinsk meteor. The 1908 event is the largest in recorded history, with an impact estimated to be similar to the explosion 10-20 mega tons of TNT. The meteor exploded just over 5 miles above the ground and flattened over 80 million trees of Siberian forest in Russia. The Chelyabinsk meteor is the most recent meteor event, and was widely watched across news and internet channels. In total the explosion of this meteor sent a shock wave across the Chelyabinsk town fringes that injured over 1,700 people.

Meteor Tail Over Chelyabinsk. Photo credit Russian Emergency Ministry.

Smaller meteor landings have been more easily recorded with phones or cameras. Although some burn out as they enter the atmosphere, there are other that can still be dangerous. In 2009 in Ontario, Canada the Grimsby meteorite broke the windshield of an SUV. In 1992, Peekskill, New York, meteorites clashed into the back of a chevy Malibu.

It is held that small meteor impacts are impossible to predict -even the Chelyabinsk is considered a small meteor. They can only be detected once they start to descend to Earth.

But what about the big impacts? What about the extinction-level events, such as the one that wiped out the dinosaurs?

Big impacts are made by asteroids, not just a piece of them, AKA a meteor. According to NASA, there are no known asteroids that will impact Earth in the next 100 years and even then, they have a very low possibility of doing so. The asteroid designated as 2009 FD has a possibility of less than .2 percent to impact Earth in 20185.

Although very unlikely, massive impacts have left trace in Earth’s surface. Craters are the evidence left from a large meteorite. Some are very noticeable like the Meteor Crater near Arizona but, others can only be truly appreciated from space.

Vredefort Crater, is located in South Africa. It’s approximately 250 km (155.3 miles) in diameter and is thought to to be about 2.02 billion years old. The asteroid that made the crater was estimated to be 6 miles wide and when it hit Earth, made a “hole 10 times deeper than the Grand Canyon.”

The Chicxulub Crater is believe what’s left of the asteroid that killed the dinosaurs. Most of it lies under water in the Yucatan Peninsula, Mexico. It’s approximately 170km (105 miles) in diameter and believed to have occurred 66 million years ago. Its particular peak ring structure was created just minutes after the impact, and although peak rings are common in space, this is the only one found on Earth.

 

Resources for Educators

  1. http://www.space.com/33695-thousands-meteorites-litter-earth-unpredictable-collisions.html
  2. http://www.space.com/33623-chelyabinsk-meteor-wake-up-call-for-earth.html
  3. https://www.universetoday.com/36398/what-is-the-difference-between-asteroids-and-meteorites/
  4. https://www.universetoday.com/19616/earths-10-most-impressive-impact-craters/