Rocky Visitors, Part 4: Meteoroids

It was a warm, peaceful day in Yucatan, Mexico when disaster suddenly struck. As dinosaurs calmly grazed in a quiet green meadow, a giant rock the size of a mountain was hurtling towards Earth at tens of thousands of miles per hour. The dinosaurs slowly gazed up at this colossal fireball, not knowing that what would happen next would be one of the most destructive events in the history of the Earth…

Welcome to Rocky Visitors part four! Today we’ll be learning about meteoroids. If you want to find out what happened to the dinosaurs on that fateful day 66 million years ago, keep reading!

What in the world is a meteoroid?

You’ve probably heard of meteorites and meteors, so you’re probably wondering what in the world (or universe) a meteoroid is. Quite simply, meteorites and meteors are types of meteoroids. Where do meteoroids come from? In the last two articles, we talked about where asteroids and comets come from. If you don’t remember, here’s a quick refresher: asteroids come from the Asteroid Belt and comets come from either the Kuiper Belt or the Oort Cloud. (Check out these articles here – asteroids, comets ). Meteoroids actually come from asteroids (and sometimes comets). They are just little bits of asteroids (or comets) that have broken off.

Ok, but what’s the difference between meteors and meteorites?

Meteors and meteorites often get confused, probably because they sound so similar.

Meteors are fragments of rock that whiz into Earth but get burned up in its atmosphere. In fact, there are around 25 million of these rocks that burn up in the sky every day! But most are really small – meteors usually range from the size of a pea to a golf ball. This is why you don’t see giant fireballs soaring across the sky every day.

Meteorites, on the other hand, have different destinies. These guys survive all the way down to the surface of the Earth without burning up. As a result, they can cause a lot of destruction. The one really big impact can be seen at the Vredefort Crater in South Africa. This crater, which is 118 miles across and is the largest known on Earth, was caused by a meteorite 2.2 billion years ago! Also, Meteor Crater near Winslow, Australia is pretty cool. It’s only less than a mile wide but is very beautiful and well-preserved. Below is an awesome image of it:

This is Meteor Crater in Australia. It was caused by a 40 to 50-meter meteorite made out of nickel and iron that hit the Earth around 50,000 years ago.

Poor dinosaurs!

Now that we know more about meteoroids, let's return to the tragedy of the dinosaurs, which began 66 million years ago. The massive fireball that was hurtling towards Earth was indeed a meteorite, and is estimated to have been around 6 miles wide! It struck a part of Mexico called the Yucatan Peninsula, and we call the crater it made the Chicxulub Crater. When the meteorite hit, it caused a bunch of destructive events across the globe. Its energy burned entire forests to the ground and cooked land dinosaurs alive. Its impact ejected tons of rocks up into the atmosphere, which, when falling back down to Earth, caused even more explosions! The meteorite also caused tsunamis, some maybe even a mile tall that would have traveled across the globe! But, most lethal of all was the sulfur, soot, and other dust the impact sent up into the air. This caused most of the sun’s rays to be blocked, which was devastating for all life. Without sunlight, the Earth got really cold and dark, and many plants and animals died. In fact, 75% of all life became extinct! This included most of the dinosaurs. This mass extinction event is known as the Cretaceous–Paleogene extinction event, or the K-pg extinction event for short.

Should I be worried about meteorites?

Meteorites are really cool, but only when they aren’t killing life and causing mass extinctions. So, how worried should we be about meteorites?

10 km meteorites

The size of the meteorite that killed the dinosaurs was around 10 kilometers or km. These guys are extremely rare and hit Earth once every 100m years or so. But don’t worry at all – the chances that a 10km asteroid will hit us in the next 100 years is almost 0%!

1 km meteorites

1km meteorites, although smaller than 10 km ones, still have the potential to do a ton of damage. This might be frightening, but for every 10 km asteroid, there are around 1000 1 km asteroids! But good news again– the chances that a 1 km asteroid will hit us in the next 10 years is close to 0%.

100m meteorites

Even smaller, but still really dangerous, are 100 m meteorites. These have the potential to destroy a small city. However, because 100 m asteroids are so hard to detect in space, we not too sure if any will hit us soon. But, the chances of the Earth being struck by a 100 m asteroid are still pretty low.

This is a dashcam photo of the Chelyabinsk Meteorite, which struck Russia in 2013. No deaths were reported, but around a thousand people got injured and many buildings got destroyed from the shockwave it created. Meteorites are dangerous!

That’s all for meteoroids in this final part of the Rocky Visitors series. Now, although you might be worried about one striking the Earth, remember that the chances of this happening are very low. In addition, there are more important and pressing issues that are happening on Earth right now!