Attack From Outer Space

February 15, 2013, starts as a normal day in Chelyabinsk [CHEL-yah-binsk], Russia. People eat breakfast, drive to work, and head to school. But for the 1.1 million people who live in this busy city, everything is about to change.

A space rock is headed for Chelyabinsk. It’s 55 feet across! And nobody knows it’s coming.

This rock has been circling close to Earth for thousands of years. Finally, this morning, it enters our atmosphere, the layer of gases surrounding our planet.

Zooming toward Earth’s surface, the rock gets hotter and hotter. The heat is so strong that the rock starts to crumble. It’s traveling 40,000 miles an hour. (Picture a rocket shooting into the sky. The rock was moving more than twice as fast!) Now it’s close to the ground, and it won’t be long until . . . it explodes!

The residents of Chelyabinsk stare as a fireball streaks across the blue-pink morning sky. It disappears in a flash of light brighter than the sun. A trail of smoke is left behind. Some people run outside or go to their windows for a better look. Others pull their cars over.

What was that? A missile? A plane crash? Aliens?!

Two looong minutes pass. And then—

BOOM! SMASH!

Walls collapse. People are knocked to the ground. Windows shatter. Razor-sharp pieces of glass fly into homes, schools, and offices. In an instant, 1,500 people are injured.

They are lucky. It could have been worse.

February 15, 2013, started as a normal day in Chelyabinsk [CHEL-yah-binsk]. This is a city in Russia. People ate breakfast, drove to work, and went to school. On that morning, a space rock flew into the atmosphere. That’s the layer of gases around Earth. The rock had been flying around Earth for thousands of years.

The rock zoomed toward Russia. It left behind a line of smoke. The rock got hotter and hotter. Then it seemed to disappear. People in the city waited to see what happened next. Two long minutes passed. And then—

BOOM! SMASH!

A thousand people got hurt by the explosion. But they were lucky. It could have been worse. No one was killed.

February 15, 2013, starts as a normal day in Chelyabinsk [CHEL-yah-binsk], Russia. People eat breakfast, drive to work, and go to school. About 1 million people live in this city. But everything is about to change.

A space rock is about to hit Chelyabinsk. It’s 55 feet across! And nobody knows it’s coming.

This rock has been flying around Earth for thousands of years. This morning, it enters the atmosphere. That’s the layer of gases around Earth.

The rock zooms toward Earth’s surface. It gets hotter and hotter. The heat is so strong that the rock starts to break. It’s traveling 40,000 miles an hour. Now it’s close to the ground, and soon . . . it explodes!

The people in Chelyabinsk stare as a fireball flies across the blue-pink sky. It disappears in a flash of bright light. A line of smoke is left behind. Some people run outside or go to their windows to look. Others pull their cars over.

What was that? A missile? A plane crash? Aliens?!

Two looong minutes pass. And then—

BOOM! SMASH!

Walls break. People fall to the ground. Windows explode. Pointy pieces of glass fly into homes, schools, and offices. About 1,500 people are hurt in an instant.

They are lucky. It could have been worse.

As the sun rises on February 15, 2013, the people of Chelyabinsk, Russia, start their mornings as usual, eating breakfast, driving to work, and heading to school. But the 1.1 million residents of this busy city are in for a very unusual day. This morning, a space rock 55 feet across—about as wide as your school gym—is headed directly for Chelyabinsk. And nobody has any idea.

This rock has been circling close to Earth for thousands of years. Finally, this morning, it enters our atmosphere—the layer of gases that surrounds our planet. 

Zooming toward Earth’s surface, the rock gets hotter and hotter. The heat is so intense that the rock starts to crumble as it travels 40,000 miles an hour—more than twice as fast as most rockets at liftoff. Now it’s about 15 miles above the ground, and it won’t be long until . . . it explodes! 

The residents of Chelyabinsk gawk, puzzled, as a brilliant fireball streaks across the blue-pink morning sky and disappears in a blinding flash of light brighter than the sun. An eerie trail of smoke is left behind. Some people run outside or go to the windows for a better look. Others pull their cars over, alarmed.

What was that? A missile? A plane crash? Aliens?!

Two uneasy minutes pass. And then—

BOOM! SMASH!

Thunderous bangs echo as invisible shock waves shake Chelyabinsk. Walls collapse. People are knocked to the ground. Windows shatter, flinging razor-sharp shards of glass into homes, schools, and offices throughout the city. In a single instant, about 1,500 people are injured.

They are lucky. It could have been worse.

Rocks From the Sky

Ever look up at the night sky and see a shooting star? Isn’t it beautiful? Don’t let the name confuse you, though. A shooting star is not really a star. It’s a meteor. A meteor produces a stream of light when it burns up in Earth’s atmosphere. Our solar system contains millions of rocks. These include asteroids, comets, and meteoroids. Meteors that are especially large and bright are called fireballs. Any meteors that make it to Earth are called meteorites.

Space rocks are leftovers from when the planets of our solar system formed about 4.5 billion years ago. The rocks move around the sun in circles called orbits. Sometimes they knock into each other, bouncing around like bumper cars. Often they fall close to us.

Each day, Earth is hit by tons of debris. But most of it burns up in the atmosphere without causing any damage.

But if an asteroid wider than a mile across were to hit Earth, it would be a disaster.

Sixty-six million years ago, a huge asteroid crashed off the coast of what is now Mexico. Scientists believe dust clouds from the explosion blocked out the sun. This caused plants and animals to die. It’s likely what led to dinosaurs becoming extinct.

Could that happen again?

Other Close Calls

Rocks from space have crashed to Earth before. Millions of years ago, one big rock hit the ground. It made huge dust clouds. Those clouds blocked the sun from plants and animals. Without sunlight, nothing could survive.

Scientists think this is why the dinosaurs became extinct.

About a hundred years ago, a meteor hit another part of Russia called Siberia. A meteor is a rock that floats in outer space. Meteors move around the sun. Sometimes meteors knock into each other. Often they fall close to us.

The meteor in Siberia knocked down millions of trees. Even people far away could feel how hot the explosion was.

Rocks From the Sky

Have you ever looked at the night sky and seen a shooting star? Isn’t it beautiful? A shooting star is not really a star, though. It’s a meteor. A meteor produces a line of light when it burns up in Earth’s atmosphere. Our solar system has millions of rocks. These include asteroids, comets, and meteoroids. Meteors that are really large and bright are called fireballs. Any pieces of rock that land on Earth are called meteorites.

Space rocks are leftovers from about 4 billion years ago. That’s when the planets of our solar system formed. The rocks now move around the sun in circles called orbits. Sometimes they knock into each other, bouncing around like bumper cars. Often they fall close to us.

Each day, Earth is hit by tons of debris. But most of it burns up in the atmosphere without causing any harm.

If an asteroid longer than a mile across were to hit Earth, it would be a big problem.

Sixty-six million years ago, a huge asteroid hit Earth. It probably led to dinosaurs becoming extinct. It crashed near Mexico. Scientists think that dust clouds from the explosion blocked out the sun. This caused plants and animals to die.

Could that happen again?

Rocks From the Sky

Ever look up at the night sky and see a shooting star? Beautiful, yes? Don’t let the name confuse you, though—a shooting star is not really a star; it’s a meteor, the stream of light produced when a rock burns up in Earth’s atmosphere. Our solar system includes millions of rocks, such as asteroids (large space rocks), comets (part rock and part ice), and meteoroids (smaller space rocks). Especially large and bright meteors, like the one in Chelyabinsk, are called fireballs. Any pieces that land on Earth are called meteorites.

Mentions of sacred rocks from the sky appear in writings from ancient civilizations. The Egyptians called meteorites “metal from the sky” and turned them into special jewelry and short, sharp knives called daggers. The Greeks and Romans saw fallen space rocks as messages from the gods. The ancient Chinese carefully recorded meteor showers.

It wasn’t until 1794, though, that German physicist Ernst Chladni proposed that meteorites come from outer space. But no one took him seriously. The common belief at the time was that rocks that fell from the sky came from Earth, having been first swept up by strong winds. Then, in April 1803, thousands of meteorites fell on the French town of L’Aigle. A physicist named Jean-Baptiste Biot went to investigate. Biot’s research finally convinced scientists that rocks can—and do—fall from space.

Now we know that space rocks are leftovers from when the planets of our solar system formed about 4.5 billion years ago. Like the planets, the rocks move around the sun in circles called orbits. Generally, they stay in the asteroid belt, an area between Mars and Jupiter. But sometimes they knock into each other, bouncing around like bumper cars, and stray close to us. Each day, Earth is bombarded by some 100 tons of space debris, most of which burns up in the atmosphere without causing any harm.

But if an asteroid larger than a mile across were to hit Earth, it would be a catastrophe.

Sixty-six million years ago, an asteroid likely led to the extinction of the dinosaurs. That asteroid was six miles across. It crashed off the coast of what is now Mexico. Scientists believe dust clouds from the explosion blocked out the sun—perhaps for months—causing plants and animals to die.

Could that happen again?

Another Close Call

The last time a meteor caused serious damage was back in 1908. Strangely, it was also in Russia. A farmer named S.B. Semenov was sitting on a porch in Siberia. This is a vast area in eastern Russia. Suddenly, the sky lit up and Semenov was knocked to the ground. Later he wrote that the heat “almost burned the shirt off me.”

Semenov was more than 40 miles away from Tunguska, where the huge space rock hit. Still, he felt its power. That space rock was much larger than the one in Chelyabinsk. The Tunguska meteor was much closer to the ground too. The blast knocked down 80 million trees in a space that was more than twice the size of New York City.

But these events are rare. Most scientists never imagined they would ever see anything like what happened in Russia. Events like the one that probably doomed the dinosaurs are even more rare. They happen only once every 100 million years or so.

Another Close Call

The last time a meteor caused problems was back in 1908. It was also in Russia. A farmer named S.B. Semenov was sitting on a porch in Siberia. Siberia is a vast area in eastern Russia. Suddenly, the sky became bright. Semenov fell to the ground. He wrote that the heat “almost burned the shirt off me.”

Semenov lived 40 miles away from Tunguska. That’s where the huge space rock hit. Still, he felt its power. It was much larger than the one in Chelyabinsk. It was much closer to the ground too. The blast knocked down   80 million trees. It hit a space twice the size of New York City.

But these events are rare. Scientists never thought they would see anything like what happened in Russia. Events like the one that probably killed the dinosaurs are even more rare. They only happen every 100 million years or so.

Another Close Call

The last time a meteoroid caused as much damage as the one in Chelyabinsk did was more than 100 years ago—by chance, also in Russia.

On the morning of June 30, 1908, a farmer named S.B. Semenov was sitting on the porch of a trading post in Siberia, a vast area in eastern Russia. Suddenly, the sky lit up and a shock wave knocked him to the ground. He felt fierce heat, writing later, “It almost burned the shirt off me.”

Semenov was more than 40 miles away from the center of what has become known as the Tunguska event. Tunguska is a faraway region of the Siberian wilderness. With the force of nearly 200 atomic bombs, the explosion felled 80 million trees across an area more than twice the size of New York City.

But because Tunguska is so remote, it took decades for scientists to piece together what happened. The mystery inspired bizarre theories—a UFO explosion, a science experiment gone wrong, a black hole passing through the planet.

In fact, what happened in Tunguska was just like what happened in Chelyabinsk, except the Tunguska meteor was much larger and much closer to the ground. These events are extremely rare; few of today’s scientists ever imagined they would live to see anything like it. Very large asteroid events, like the one that probably doomed the dinosaurs, are even more rare. They happen only once every 100 million years or so.

Money for Meteorites

What happened in Chelyabinsk reminds us of something that’s easy to forget: We live on a planet that is drifting through space, and there are objects drifting along with us. Someday, those objects might put us in danger.

But scientists around the world are working hard to make sure that what happened in Chelyabinsk never happens again.

Fortunately, no one in Chelyabinsk was killed. No one was seriously hurt, either. In fact, many people in the area started a new hobby: They hunt for meteorites. Even small pieces of the fireball can be worth thousands of dollars.

If you were to see a meteorite, though, you probably wouldn’t think it was anything special.

Most look an awful lot like boring old black rocks.

You’d probably walk right by it.  

Rocks From the Sky

Meteors don’t crash into Earth very often. This only happens about once every 100 million years. So scientists never thought they would see a big space rock crash to the ground.

Scientists are working hard to make sure meteors don’t cause problems like they did in Russia.

These days, people in Chelyabinsk have a new activity. They look for pieces of meteors that are still left on the ground.

Even small pieces can be worth thousands of dollars. But they look just like old rocks. If you saw one, you would probably walk right by it.  

Searching for Rocks

What happened in Chelyabinsk reminds us of something. We live on a planet that is floating in space, and there are objects floating along with us. Someday, those objects might put us in danger.

But scientists around the world are working hard to learn more about what happens in space. They want to make sure that what happened in Chelyabinsk never happens again.

No one in Chelyabinsk was killed. No one was seriously hurt, either. In fact, many people in the area started a new activity: They look for meteorites. Small pieces of the fireball can be worth thousands of dollars.

If you found a meteorite, though, you probably wouldn’t think it was worth picking up.

Most look just like old black rocks.

You’d probably walk right by it. 

We’re Not Alone

What happened in Chelyabinsk is a reminder of something that’s easy to forget: We live on a planet that is drifting through space, and we’re not alone. Drifting along with us are objects that may someday pose a threat. But scientists around the world are working feverishly to ensure that such an event never happens again.

And fortunately, no one in Chelyabinsk was killed. Most of the injuries were minor. Many people in the area have a new hobby: hunting for meteorites. Even small fragments of the fireball can be worth thousands of dollars.

If you were to see a meteorite, though, you probably wouldn’t think it was anything special. Most look an awful lot like boring old black rocks.

You’d probably walk right by it.