An Eiffel Tower-sized asteroid is about to whiz by Earth. When it returns in 8 years, it could cross paths with our satellites.

asteroid earth fly by
An artist’s illustration of asteroids flying by Earth.

  • An asteroid called Apophis, after the ancient Egyptian god of chaos, will fly by Earth Friday night.
  • The space rock is more than 1,100 feet wide — wider than the Eiffel Tower is tall.
  • When Apophis returns in 2029, its path could intersect with high-altitude satellites in Earth’s orbit.
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An asteroid nearly four football fields wide is about to zoom by Earth.

The space rock is named 99942 Apophis, after the ancient Egyptian god of chaos. It’s is wider than the Eiffel Tower is tall: about 1,115 feet (340 meters).

On Friday night at 8:15 p.m. ET, the asteroid will come within 10.4 million miles of Earth’s surface. That’s about 44 times the distance between Earth and the moon. But Apophis’ next close flyby, on April 13, 2029, will bring the asteroid within 19,000 miles of Earth – that’s in between our planet and the moon. It will be the closest any asteroid of Apophis’ size has come to Earth’s surface that scientists have known about in advance, according to NASA

That future approach will even be close enough that the asteroid could collide with high-altitude communications satellites orbiting Earth.

The animation below shows what the distance between Apophis and Earth will be eight years from now. The blue dots represent orbiting satellites, and the International Space Station is in pink.

Preparing for Apophis’ return

Apophis won’t be visible to the naked eye tonight – you’d need a telescope with at least a foot-long diameter to see it. But Rome’s Virtual Telescope Project is offering an online viewing session at 7 p.m. ET.

The asteroid’s discovery made waves in 2004, since astronomers calculated at the time that there was a small chance it could hit the planet in 2029. NASA scientists have since revised that estimate.

“We have known for some time that an impact with Earth is not possible during the 2029 close approach,” Dave Tholen, a researcher at the University of Hawai’i Institute for Astronomy who helped discover Apophis, said in October.

Every time an asteroid nears Earth, it’s a chance for astronomers to study the space rock and learn about its shape and spin.

When scientists first spotted Apophis in June 2004, they had just two days to inspect it before weather and technical issues got in the way. No images exist of the rock’s surface. So this imminent close pass, as well as the one in 2029, will help scientists investigate Apophis’ composition.

“The Apophis close approach in 2029 will be an incredible opportunity for science,” Marina Brozović, a radar scientist at NASA’s Jet Propulsion Laboratory, said in 2019. “We’ll observe the asteroid with both optical and radar telescopes. With radar observations, we might be able to see surface details that are only a few meters in size.”

During that 2029 flyby, Apophis will be visible to the naked eye, appearing as a fast-moving point of light that starts in the night sky over the Southern Hemisphere and moves across the globe from east to west.

The NASA animation below shows Apophis’ path on April 13, 2029.

 

Apophis has a 1 in 380,000 chance of striking Earth in 2068

Apophis originated from the asteroid belt between Mars and Jupiter. So far, NASA knows it is made up of silicate rocks, nickel, and iron. Radar images suggest it looks like a peanut.

After 2029, Apophis will have more near-Earth encounters, passing by again in 2036 and 2068. There’s no chance of an impact in 2036, but NASA calculations suggest a 1 in 380,000 chance that Apophis could strike in 2068.

Until last year, astronomers thought it was impossible that Apophis would strike Earth in 2068, but that changed after Tholen’s team presented new research at the annual meeting of the American Astronomical Society. The group showed the asteroid was changing speed and direction over time.

asteroid vesta
The asteroid Vesta in space.

These changes come from a process known as Yarkovsky acceleration: As asteroids absorb energy from the sun, they radiate the energy out as heat, which slightly changes their orbital paths.

The recent research found that this is happening to Apophis.

The asteroid’s orbit is shifting by about 558 feet per year, Tholen said – which is “enough to keep the 2068 impact scenario in play.”

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The space rock that doomed the dinosaurs was shrapnel from a comet that flew too close to the sun, a Harvard study suggests

dinosaur asteroid meteor
An artist’s depiction of the moment the Chicxulub asteroid struck present-day Mexico 66 million years ago.

About 66 million years ago, a space rock more than 6 miles wide collided with Earth, striking land that is now part of Mexico.

The impact sparked wildfires that stretched for hundreds of miles, triggered a mile-high tsunami, and released billions of tons of sulfur into the atmosphere. That gaseous haze blocked the sun, cooling the Earth and dooming the dinosaurs, along with 75% of all life on the planet.

But the origins of that dinosaur-killing rock, named Chicxulub, have remained a mystery. 

Most theories suggest Chicxulub was a massive asteroid; hundreds of thousands of these rocks sit in a donut-shaped ring between Mars and Jupiter. But in a study published Monday, two Harvard astrophysicists suggested an alternate idea: that Chicxulub wasn’t an asteroid at all, but a piece of shrapnel from an icy comet that had been pushed too close to the sun by Jupiter’s gravity.

Asteroids and comets are both classified as space rocks by NASA, but they differ in key ways: Comets form from ice and dust outside our solar system and are generally small and fast-moving, whereas rocky asteroids are larger, slower, and form closer to the sun.

“We are suggesting that, in fact, if you break up an object as it comes close to the sun, it could give rise to the appropriate event rate and also the kind of impact that killed the dinosaurs,” Avi Loeb, an astrophysicist and cosmologist at Harvard University and co-author of the new study, said in a press release

The solar system acts like a ‘pinball machine’ for comets

asteroid meteor armageddon shutterstock
An artist’s depiction of an asteroid approaching Earth.

Most asteroids come from the asteroid belt between the solar system’s inner and outer planets. But NASA scientists who keep tabs on space objects that pass near Earth have yet to figure out where Chicxulub came from. 

In the new study, published in the journal Scientific Reports, Loeb and his co-author, Amir Siraj, suggest Chicxulub didn’t come from the asteroid belt. Rather, they say it more likely originated outside our solar system, in an area called the Oort cloud

Think of the Oort cloud as ring made of 1 trillion pieces of icy debris, which sits beyond the farthest reaches of the solar system, surrounding it. It’s located at least 2,000 times farther away from the sun than Earth is. Comets that originate in the Oort cloud are known as long-period comets because they take so long to complete one orbit around the sun.

But these comets can sometimes get pulled off-course by the gravity of massive planets like Jupiter. Such a tweak to a comet’s orbit could send it hurtling on a path much closer to the sun. 

“The solar system acts as a kind of pinball machine,” Siraj said in the release.

Comets that get near the sun are called “sungrazers.” The new study calculated that about 20% of Oort cloud comets are sungrazers. As they approach our star, its gravity starts to pull them apart. Fragments of comet slough off and may careen toward nearby planets. 

This, the study authors say, is “a satisfactory explanation for the origin of the impactor” that killed the dinosaurs.

The asteroid-versus-comet argument isn’t settled

Chicxulub_impact asteroid
A painting depicting an asteroid slamming into tropical, shallow seas of the Yucatan Peninsula in what is today southeast Mexico. The aftermath is believed to have caused the extinction of the dinosaurs.

Siraj and Loeb aren’t the only scientists who think a comet, not an asteroid, doomed the dinosaurs. A group of researchers from Dartmouth College similarly suggested in 2013 that a high-speed comet could have created the Chicxulub crater. 

Chicxulub hit Earth at a speed of 12 miles per second (43,200 mph), which is about 30 times faster than the speed of a supersonic jet. The resulting 100-mile-wide crater extended 12 miles into the depths of the Gulf of Mexico. Some scientists have estimated the asteroid’s power was equivalent to 10 billion of the atomic bombs used in World War II.

But not all researchers are convinced a comet caused that destruction.

Natalia Artemieva, a senior scientist at the Planetary Science Institute in Arizona, told The New York Times that comet fragments from a sungrazer would have been too small to create the Chicxulub crater. And Bill Bottke, a planetary scientist at the Southwest Research Institute in Colorado, suggested that the study overestimates the frequency of sungrazers – and, consequently, the amount of fragments those comets produce.

Existing evidence favors the idea that Chicxulub was an asteroid, “but it’s not conclusive,” Bottke told the Times. “There’s still wiggle room if somebody really wants it to be a comet. I just think making that case is really hard.”

Siraj and Loeb, however, said their theory is supported by a type of material found deep inside the Chicxulub crater and other craters in South Africa and Kazakhstan. That substance, carbonaceous chondrite, may have come from comets. Whereas just 10% of asteroids from the asteroid belt are composed of carbonaceous chondrites, the material “could potentially be widespread in comets,” the study authors wrote.

The only samples ever collected from a comet in space were brought back in 2006. They revealed that object, called Wild 2, was composed of carbonaceous chondrite.

kuiper belt oort cloud
Artwork depicting the icy cores of baby comets beyond Neptune at the edge of our solar system.

Finding the correct answer in the Chicxulub debate is useful because it could help researchers figure out the likelihood of a similar impact event in the future. Only two to three comets from the Oort Cloud have hit Earth during the last 500 million years, according to one study. By contrast, according to the Planetary Society, a Chicxulub-sized asteroid impacts Earth every 100 million years or so

Siraj and Loeb modeled how many long-period comets get close enough to the sun to shed large fragments in the direction of Earth. Their numbers suggest 10 times more Chicxulub-sized objects hit Earth over its history than scientists previously thought.

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