A Harvard-led team is launching a new project to search for physical evidence of aliens and their technology

Artist's impression of 'Oumuamua
An artist’s impression of interstellar object ‘Oumuamua.

When the first interstellar object ever observed, ‘Oumuamua, careened past Earth in 2017, it seemed to be accelerating. That’s not what most space rocks do – which is in part why Harvard astrophysicist Avi Loeb says ‘Oumuamua was an alien spaceship.

Although most researchers agree that the object was a space rock – either a comet or piece of a tiny planet – Loeb thinks there are countless other objects like ‘Oumuamua whizzing by our planet, some of which could come from aliens, too. So he launched a program to find them.

On Monday, Loeb announced an initiative called the Galileo Project – after the Italian astronomer – that will search for physical evidence of alien technologies and civilizations.

“It’s a fishing expedition, let’s just go out and catch whatever fish we find,” Loeb said in a press conference. “And that includes objects close to Earth, hovering within our atmosphere, or objects that came from outside the solar system that look weird.”

The $1.75 million project, backed by at least four philanthropists, aims to use a network of Earth-based telescopes to look for interstellar objects that could be extraterrestrial in nature. The group will also hunt for potential alien ships in Earth’s orbit, as well as unidentified flying craft in our atmosphere.

Finding interstellar objects before they pass Earth

oumuamua 1I 2017 u1 solar system trajectory illustration comet asteroid or alien spaceship nasa swri esa stsci PIA22357_fig1
An illustration of ‘Oumuamua flying through the solar system in 2017.

By the time astronomers became aware of ‘Oumuamua’s existence, it was already zipping away at 196,000 mph. Several telescopes on the ground and one in space took limited observations, but astronomers had just a few weeks to study the strange, skyscraper-sized object before it got too far away.

That left many questions about what the object was and where it came from. In a book Loeb published in January, “Extraterrestrial: The First Sign of Intelligent Life Beyond Earth,” he describes ‘Oumuamua as a defunct piece of alien technology.

“The object has anomalies that merit some attention – things that do not line up in the ways we expected,” Loeb told Insider ahead of the book’s publication, adding, “when something doesn’t line up, you should say it.”

Two years after ‘Oumuamua’s discovery, astronomers spotted a second interstellar object: a comet called 2I/Borisov. With the Galileo Project, Loeb and a team of 14 other researchers hope to spot future interstellar objects early as they approach Earth. To do this, they plan to use the Pan-STARRS telescope in Hawaii and an 8-meter-wide telescope currently under construction at the Vera C. Rubin Observatory in Chile.

Early detection could enable scientists to send probes to these objects, according to Frank Laukien, a visiting scholar at Harvard and a co-founder of the Galileo Project.

“We should, next time, have much better data much earlier, and maybe land on them or get very, very close to them,” Laukien said in the press conference.

Searching for signs of extraterrestrial technology

vera rubin telescope
Large Synoptic Survey Telescope building at Vera Rubin observatory at Cerro Pachón, Chile, in September 2019.

Loeb describes the new project as complementary to the SETI Institute, which searches for extraterrestrial life using radio telescopes. But the Galileo Project, he said, will search for physical evidence of alien civilizations, rather than radio signals. That includes potential alien satellites that could be orbiting Earth or fragments of extraterrestrial craft. (One of Loeb’s hypotheses is that ‘Oumuamua is a piece of lightsail or antenna that broke off a larger ship.)

Loeb also plans to examine unidentified aerial phenomena, or UAPs, within Earth’s atmosphere.

Last month, US intelligence officials released a report describing 144 incidents since 2004 in which military personnel encountered UAPs. One of those incidents turned out to involve a deflating balloon, but the rest remain unexplained, the report concluded.

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A still from Navy footage of unidentified aerial phenomena.

“It’s an unusual admission by the government, saying there are objects in our sky we don’t fully understand,” Loeb said.

According to the Galileo Project’s website, these UAPs could be artifacts of an extinct alien civilizations or active extraterrestrial equipment. So the group hopes to image future UAPs in higher resolution by creating a network of 1-meter telescopes around the world.

Such telescopes, which cost about $500,000 each, can spot details just 1 millimeter in size on objects the size of a person a mile away.

“That could help us distinguish a label saying ‘thing made in country X,’ from a label saying, ‘made by exoplanet Y,'” Loeb said.

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Physicist Avi Loeb on stage in New York in 2016.

He added that the Galileo team plans to make its data public to encourage other scientists to engage in the search, too.

“Finding others on cosmic streets will help us mature – help us realize were not the sharpest cookies in the jar, and intelligent life that is way beyond us may exist out there,” Loeb said.

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The dinosaurs may have already been going extinct before the cataclysmic space rock hit Earth, new findings suggest

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

It’s tempting to ponder what life on Earth might have looked like had a space rock not hit 66 million years ago. That impact in present-day Mexico doomed the dinosaurs and a majority of land and marine species. In its absence, would humans and other mammals have eventually duked it out with T. rex and triceratops?

The answer is probably not, according to a study published Tuesday.

That research found that six major groups of dinosaurs were slowly going extinct over the 10 million years prior to the crash. The impact’s consequences – mile-high tsunamis, raging fires, and a choking cloud of thick dust and sulfur that blotted out the sun – were merely a nail in the dinosaurs’ coffin.

“The meteorite is seen as a coup de grâce for dinosaurs, which finished them off,” Fabien Condamine, a research scientist at the University of Montpellier in France who co-authored the new study, told Insider.

Condamine and his collaborators suggest that a period of global cooling may have contributed to a decline in the overall number of dinosaur species, which then made it impossible for the animals to recover after the cataclysmic event.

“Many paleontologists think dinosaurs would have continued to live if the asteroid did not hit Earth. Our study brings new information for this question, and it seems that dinosaurs were not in good shape before the impact,” Condamine said.

Dinosaurs were already on their way out

T. rex
A full-grown Tyrannosaurus rex weighed between 6 and 9 tons and was up to 43 feet long.

The researchers behind the new study looked at 1,600 fossils from 247 dinosaur species that lived during the late Cretaceous period – from about 100 million to 66 million years ago. That group includes two-legged carnivores like the T. rex, triceratops, and duck-billed dinosaurs.

The team grouped them into six large families, then analyzed how the diversity of species in those families changed over time. The results show that across all six groups, the number of species started to gradually decline 76 million years ago, prior to the space-rock impact.

“We do not find that dinosaur diversity was high and diversifying toward the end of the Cretaceous, as previously thought,” Condamine said.

His isn’t the first group of scientists to suggest that dinosaurs actually went extinct gradually. A 2016 study found that as species of dinosaurs that had been around on Earth a while went extinct, no newer species replaced them. Although questions lingered as to whether that conclusion was simply the product of an incomplete fossil record, this new study shows that older species did indeed have higher extinction rates than younger ones.

An herbivore monopoly

Arctic dinosaur hadrosaur
A painting of Ugrunaaluk kuukpikensis, a species of duck-billed dinosaur that lived during the Cretaceous period.

In the late Cretaceous period, the planet began to cool: Starting 80 million years ago, global temperatures dropped by about 13 degrees Fahrenheit (7 degrees Celsius).

Given that dinosaurs relied on the temperature of their environment to regulate their body heat, Condamine said, that change in climate might have played a role in their extinction rates.

“Warm periods favored dinosaur diversification whereas cooler periods led to enhanced extinctions,” the study authors wrote.

Another possible explanation for the dinosaurs’ decline is a change in the number of herbivore species in the ecosystem. Hadrosaurs, or duck-billed herbivores, seem to have dominated between 76 million and 66 million years ago – out-competing their fellow leaf-eaters like triceratops and the clubbed-tailed, armored ankylosaurs. That contributed to the decline of those other herbivores.

“Removing herbivores can make the entire ecosystems more prone to extinction cascades,” Condamine said.

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A second space rock hit Earth after the one that doomed the dinosaurs – a nail in the coffin of the mass extinction

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

About 66 million years ago, Earth took a one-two punch, according to a new study.

First came a space rock 6-miles-wide that struck present-day Mexico. The impactor, named Chicxulub, contributed to the demise of the dinosaurs, along with 50% to 75% of life on Earth.

Then, 650,000 years later, a mile-sized asteroid known as Boltysh struck. The rock carved out a 15-mile-wide crater into what is now central Ukraine.

Scientists once thought both Boltysh and Chicxulub contributed to the mass extinction that doomed the dinosaurs. But according to the study published Friday in the journal Science Advances, Boltysh likely impacted Earth long after the last victims of the extinction died out.

“I believe the extinction was essentially done and dusted” by the time Boltysh hit, Annemarie Pickersgill, a researcher at the University of Glasgow who specializes in meteorite impacts and co-author of the new study, told Insider.

While it’s unlikely Boltysh exacerbated the die-off, Pickersgill said the second impact may have delayed Earth’s recovery from the catastrophic extinction.

Analyzing rocks that melted during the Boltysh impact

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A piece of shocked quartz from the Boltysh impact crater in the Ukraine.

Scientists discovered the Boltysh impact in 2002, and an initial study suggested the asteroid had hit 2,000 to 5,000 years before Chicxulub did.

Pickersgill said that her team had intended to date the Boltysh crater with more precision, but she didn’t expect their findings to upend previous research.

“I was surprised to find that the age for Boltysh was after​ Chicxulub,” she said.

The researchers first analyzed two samples from deep within the crater, more than one-third of a mile underground. The heat from the asteroid impact had melted the rocks, so dating them allowed Pickersgill to piece together when Boltysh hit.

Then, the team looked at samples from a layer of sediment in Montana that coincided with the Chicxulub impact. Using radiometric dating – a technique that determines how long it takes for radioactive material in the rocks to decay – the team determined the Boltysh rocks melted about 650,000 years after Chicxulub struck.

Boltysh may have contributed to a burst of global warming

Chicxulub_impact asteroid
This painting depicts an asteroid slamming into tropical, shallow seas of the sulfur-rich Yucatan Peninsula in what is today southeast Mexico. The aftermath of this immense asteroid collision, which occurred approximately 65 million years ago, is believed to have caused the extinction of the dinosaurs and many other species on Earth.

The updated age for the Boltysh crater coincides with a period of intense global warming known as the lower C29 hyperthermal, the study authors said.

During a hyperthermal event, which can last up to 40,000 years, average global temperatures can increase by 5.4 degrees Fahrenheit (3 degrees Celsius).

Pickersgill’s team hasn’t determined yet whether the asteroid caused the hyperthermal.

But she said there is evidence that suggests Chicxulub first cooled the Earth’s climate, then warmed it.

When the dino-killing rock hit, it kicked up a cloud of dust, sulfur, and carbon dioxide into the atmosphere. That gaseous haze blocked the sun for a couple of decades, one study suggests, cooling the Earth.

During those few decades, most of Earth’s land and marine species went extinct.

Eventually, the Chicxulub cloud dissipated and the remaining sulfur and carbon in the atmosphere – which trap heat on Earth’s surface – started warming the planet.

But once Boltysh hit, that impact may have released additional gases into the air and exacerbated that warming. This could’ve made it more difficult for Earth’s species to recover following the mass extinction.

Research suggests it took 9 million years for the number of different species in North America to return to pre-Chicxulub levels.

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A NASA probe successfully collected 2 oz. of space rock from a distant asteroid and is blasting its way back to Earth

OSIRIS REx collection
An artist rendering of OSIRIS-REx collecting samples from the surface of an asteroid.

  • A NASA spacecraft carrying samples from an asteroid began a journey back to Earth on Monday.
  • OSIRIS-REx is carrying a 2 oz. sample from the surface of an asteroid called Bennu.
  • It is the largest sample collected since the Apollo moon missions. It’s due to arrive in 2023.
  • See more stories on Insider’s business page.

A spacecraft carrying around 2 ounces of dust from the surface of an asteroid is on its way back to Earth.

The spacecraft, called OSIRIS-REx, launched its thrusters for 7 minutes on Monday to leave the asteroid Bennu, NASA said in a statement on Monday.

The probe had collected 60 grams, or about 2 ounces, of carbon-rich space dust, NASA said.

This is the largest sample collected since the manned Apollo missions to the Moon, the BBC reported.

A video from NASA’s Goddard Space Flight Center in Greenbelt, Maryland, shows what the next steps are for the spacecraft:

If all goes to plan, the spacecraft should circle the sun twice before it comes close to Earth.

OSIRIS-REx return to Earth from Bennu
OSIRIS-REx should circle the Sun twice before approaching Earth, NASA said.

Once it is within 6,000 miles of Earth, a capsule carrying the samples should be released.

NASA expects the sample will land in the desert in Utah on September 24, 2023.

OSIRIS-REx was launched almost five years ago. It is the first mission NASA has sent to collect samples from an asteroid, CNN reported.

Its main purpose was to confirm whether measurements made from Earth were accurate, NASA said in a statement.

Information such as this could be a stepping stone for future space missions going into deeper space.

OSIRIS-REx first got close to Bennu in 2018. Before collecting the samples, it circled the asteroid, collecting information and planning where to land.

The 20 ft. long, 8 ft. wide probe is also carrying tools, such as spectrometers and a camera, which took measurements of the asteroid’s surface.

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An image of the asteroid Bennu was snapped by OSIRIS-REx from a 15 miles away on December 2, 2018.

These measurements have already confirmed predictions from NASA that the asteroid’s carbon-rich soil contained oxygen and hydrogen molecules.

This suggests that Bennu might have interacted with water at some point.

The scientists were surprised to see, when the probe got closer, that the asteroid’s surface was not smooth, as they had predicted, but instead was littered with boulders.

This made the descent to the asteroid more tricky.

It finally touched down on Bennu on Oct 20, 2020. The collection arm shot out nitrogen, which disturbed the asteroid’s surface to bring the sample into the collection chamber, Insider’s Morgan McFall-Johnsen reported.

OSIRIX-REx
A schematic shows how the collection arm shot nitrogen into the asteroid’s surface to collect soil samples.

Onboard cameras showed how it sucked up dust from the asteroid’s surface to store it in a container.

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In a NASA simulation of an asteroid impact, scientists concluded they couldn’t stop a space rock from decimating Europe

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

Scientists around the world have been bamboozled this week by a fictitious asteroid heading toward Earth.

A group of experts from US and European space agencies attended a week-long exercise led by NASA in which they faced a hypothetical scenario: An asteroid 35 million miles away was approaching the planet and could hit within six months.

With each passing day of the exercise, the participants learned more about the asteroid’s size, trajectory, and chance of impact. Then they had to cooperate and use their technological knowledge to see if anything could be done to stop the space rock.

The experts fell short. The group determined that none of Earth’s existing technologies could stop the hypothetical asteroid from striking given the six-month timeframe of the simulation. In this alternate reality, the asteroid crashed into eastern Europe.

As far as we know, no asteroids currently pose a threat to Earth in this way. But an estimated two-thirds of asteroids 460 feet in size or bigger – large enough to wreak considerable havoc – remain undiscovered. That’s why NASA and other agencies are attempting to prepare for such a situation.

“These exercises ultimately help the planetary-defense community communicate with each other and with our governments to ensure we are all coordinated should a potential impact threat be identified in the future,” Lindley Johnson, NASA’s planetary defense officer, said in a press release.

6 months is not enough time to prepare for an asteroid impact

The fictitious asteroid in the simulation was called 2021PDC. In NASA’s scenario, it was first “spotted” on April 19, at which time it was thought to have a 5% of hitting our planet on October 20, six months after its discovery date.

But Day 2 of the exercise fast-forwarded to May 2, when new impact-trajectory calculations showed that 2021PDC would almost certainly hit either Europe or northern Africa. The participants in the simulation considered various missions in which spacecraft could try to destroy the asteroid or deflect it off its path.

hypothetical impact
The predicted impact region for 2021 PDC on Day 2 of a NASA-led asteroid-impact simulation.

But they concluded that such missions wouldn’t be able to get off the ground in the short amount of time before the asteroid’s impact.

“If confronted with the 2021PDC hypothetical scenario in real life, we would not be able us to launch any spacecraft on such short notice with current capabilities,” the participants said.

They also considered trying to blow up or disrupt the asteroid using a nuclear explosive device.

“Deploying a nuclear disruption mission could significantly reduce the risk of impact damage,” they found.

Still, the simulation stipulated that 2021PDC could be anywhere from 114 feet to half a mile in size, so the chance that a nuke could make a dent was uncertain.

Day 3 of the exercise skipped ahead to June 30, and Earth’s future looked grim: 2021PDC’s impact trajectory showed it headed for eastern Europe. By Day 4, which fast-forwarded to a week before the asteroid impact, there was a 99% chance the asteroid would hit near the border between Germany, the Czech Republic, and Austria. The explosion would bring as much energy as a large nuclear bomb.

All that could be done was evacuate the affected regions ahead of time.

Most asteroids fly under the radar, and many are spotted too late

dinosaur asteroid meteor
An artist’s depiction of the moment the Chicxulub asteroid struck the land that is now Mexico 66 million years ago.

It’s tempting to assume that in the real world, astronomers would spot an asteroid akin to 2021PDC with much more notice than six months. But the world’s ability to surveil near-Earth objects (NEOs) is woefully incomplete.

Any space rock with an orbit that takes it within 125 million miles of the sun is considered an NEO. But Johnson said in July that NASA thinks “we’ve only found about a third of the population of asteroids that are out there that could represent an impact hazard to the Earth.”

Of course, humanity hopes to avoid a surprise like the dinosaurs got 65 million years ago, when a 6-mile-wide asteroid crashed into the Earth. But in recent years, scientists have missed plenty of large, dangerous objects that came close.

comet neowise japan
Comet Neowise appears in the sky over Nayoro, Hokkaido, Japan, July 11, 2020.

Comet Neowise, a 3-mile-wide chunk of space ice, passed with 64 million miles of Earth in July. Nobody knew that comet existed until a NASA space telescope discovered it approaching four months prior.

In 2013, a meteor about 65 feet in diameter entered the atmosphere traveling 40,000 mph. It exploded over Chelyabinsk, Russia, without warning, sending out a shock wave that broke windows and damaged buildings across the region. More than 1,400 people were injured.

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The Chelyabinsk meteor streaking across the Russian sky.

And in 2019, a 427-foot-wide, “city-killer” asteroid flew within 45,000 miles of Earth. NASA had almost no warning about it.

That’s because currently, the only way scientists can track an NEO is by pointing one of Earth’s limited number of powerful telescopes in the right direction at the right time.

To address that problem, NASA announced two years ago that it would launch a new space telescope dedicated to watching for hazardous asteroids. That telescope, named the Near-Earth Object Surveillance Mission, along with the European Space Agency’s newly launched Test-Bed Telescope and the Flyeye Telescope that’s being built in Italy, should eventually bolster the number of NEOs we can track.

NASA is testing ways to stymie an asteroid

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An illustration of the DART spacecraft near an asteroid.

NASA has investigated the options scientists would have if they were to find a dangerous asteroid on a collision course with Earth. These include detonating an explosive device near the space rock, as the exercise participants suggested, or firing lasers that could heat up and vaporize the asteroid enough to change its path.

Another possibility is sending a spacecraft up to slam into an oncoming asteroid, thereby knocking it off its trajectory. This is the strategy NASA is most serious about: Later this year, the agency is scheduled to launch a test of such a technology. The Double Asteroid Redirection Test (DART) will send a spacecraft to the asteroid Dimorphos and purposefully hit it in the fall of 2022.

NASA hopes that collision will change Dimorphos’s orbit. While that asteroid isn’t a threat to Earth, the mission could prove that redirecting an asteroid is possible with enough lead time.

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A small asteroid that hit Botswana took 23 million years to get here from the asteroid belt, astronomers found

vesta fragment botswana 2018 LA
Fragment of asteroid 2018 LA recovered in the Central Kalahari Game Reserve in central Botswana.

  • Astronomers have uncovered fragments of a 6-foot-wide asteroid that struck Botswana in 2018.
  • According to a new study of those fragments, the space rock originated from the asteroid belt.
  • Scientists estimate the asteroid’s journey across the solar system took nearly 23 million years.
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In the early hours of June 2, 2018, astronomers at the University of Arizona saw a faint dot of light moving across the sky.

It was an asteroid, which loomed larger and larger as it approached Earth. A few hours later, the 6-foot-wide space rock – named 2018 LA – caught fire as it roared through the atmosphere at a blistering 38,000 miles per hour. It broke into tiny fragments that rained down across Botswana.

A group of researchers raced to the end of that fireball’s path to hunt for the rare fragments, since they held clues about the asteroid’s origins.

“This is only the second time we have spotted an asteroid in space before it hit Earth over land,” Peter Jenniskens, an astronomer at the SETI Institute, said in a press release.

Jenniskens’ team eventually found 23 pieces of the asteroid in Botswana’s Central Kalahari Game Reserve. According to a new study from the group, an analysis of those fragments showed that 2018 LA was actually a piece of a larger asteroid called Vesta, which is the brightest and second-largest asteroid in our solar system.

By dating the elements inside the asteroid fragments, Jenniskens’ team determined that the space rock had been traveling for nearly 23 million years after it broke off Vesta.

‘A national treasure of Botswana’

vesta fragment botswana 2018 LA
Astronomers gather around a piece of asteroid 2018 LA recovered in the Central Kalahari Game Reserve in central Botswana.

Jenniskens’ team almost struck out in their first hunt for asteroid fragments. But five days in, on their last day searching in the game reserve, the group found their first meteorite just 100 feet from their camp. (Asteroids that reach Earth’s surface are called meteorites.)

It was just over an inch long and weighed 18 grams, he said.

“The meteorite is named ‘Motopi Pan’ after a local watering hole,” Mohutsiwa Gabadirwe, a researcher from the Botswana Geoscience Institute who co-authored the study, said in the release. “This meteorite is a national treasure of Botswana.”

During a second expedition in October 2018, the team found the other 22 meteorite pieces.

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An artist’s concept of an asteroid belt.

The researchers analyzed the metal content and make-up of those fragments, and determined that they belong to a class of meteorites called Howardite-Eucrite-Diogenite (HED) meteorites. This whole group likely originated from Vesta, in the asteroid belt between Mars and Jupiter.

According to the study authors, one-third of all HED meteorites found on Earth broke off of Vesta nearly 23 million years ago, when it was struck by another space object. They think that’s true of this asteroid, too.

asteroid vesta
The asteroid Vesta in space.

The fragments’ composition also offers hints about Vesta’s violent past. An examination of the minerals inside Motopi Pan suggest the rock melted and reformed twice: 4.6 billion years ago then 4.2 billion years ago.

“Billions of years ago, two giant impacts on Vesta created a family of larger, more dangerous asteroids,” Jenniskens said. “The newly recovered meteorites gave us a clue on when those impacts might have happened.”

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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.
  • Visit the Business section of Insider for more stories.

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

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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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