The asteroid that will come closer to Earth than ever before in human history

Friday the 13th may be considered an unlucky day, but at 5:45 AM EDT (11:45 AM CEST) on Friday, April 13, 2029, it will prove just the opposite when an asteroid the size of a “dinosaur killer” safely passes by Earth.

Everyone will be watching. With a diameter of about 375 meters, asteroid Apophis is larger than 90% of space rocks.

It will pass just 19,635 miles (31,600 kilometers) from Earth’s surface, the closest approach to an asteroid of this size that humanity has ever experienced. It will pass between Earth’s geostationary satellites and the Atlantic Ocean, just one-tenth the distance between Earth and the moon.

Apophis will be visible to the naked eye. As it crosses the Atlantic Ocean, a few billion people in Europe, Africa and Asia can see it in the night sky for a few hours when the sky is clear.

Discovered exactly 20 years ago this week, here’s everything you need to know about asteroid Apophis:

‘Demon of Chaos’

Asteroid 99942 Apophis was discovered on June 19, 2004 by astronomers at Kitt Peak National Observatory, who revealed that this stony, S-type asteroid orbits the Sun every 324 days and comes close to Earth about every ten years. It made headlines after an article was published calculating that it could hit Earth in 2029, 2036 or 2068. It was therefore named after Apophis, the Egyptian demon of chaos and destruction.

Even though there was only a 2.7% chance of a direct hit by Apophis, the devastation caused by the impact on Earth (the crater it would leave would be larger than the impact of the asteroid that killed the dinosaurs) shocked astronomers to understand his job. more detailed. In 2021, radar observations by NASA’s Goldstone Deep Space Communications Complex, California, and the Green Bank Observatory, West Virginia, refined its orbit in March 2021. It was announced that Apophis would not hit Earth in 2029, 2036 or 2068.

Future threat?

However, an asteroid’s orbit can only be calculated so far into the future. Although the next time it comes close to Earth, in 2044, it will be at a greater distance, astronomers can only rule out an impact within the next 100 years.

The calculations are difficult because a short flight – like the one in 2029 – will change Apophis’ orbit so that it could hit Earth in a future orbit. However, astronomers have reduced the uncertainty in Apophis’ orbit from hundreds to just a few kilometers.

Apophis’s 2029 close pass is a rare opportunity to visit, so NASA already has a spacecraft in hot pursuit. This short pass is seen as the perfect opportunity to learn more about planetary defenses and how an asteroid reacts when passing so close to a body with such enormous gravity. It is thought that Apophis will be squeezed so heavily that asteroidquakes and landslides could result.

Mission to Apophis

Keeping a close eye on it will be NASA’s OSIRIS-Apophis Explorer (OSIRIS-APEX) spacecraft. It is the same spacecraft that visited asteroid Bennu in 2020. It was then called OSIRIS-REx, NASA’s first asteroid sample return mission, and returned a package of samples to Utah in September 2023 before being diverted to Apophis in a mission expansion that cost NASA $200 million. OSIRIS-APEX will orbit Apophis for 18 months as it passes Earth in 2029.

The European Space Agency is also considering a mission to Apophis, the Rapid Apophis Mission for SECurity and Safety (RAMSES) mission, which will launch in 2027.

What scientists are learning now by sending spacecraft to study Apophis in 2029 is about how a remnant of the early solar system responds to gravity. The findings could be crucial for future Earthlings hundreds of years from now, when the massive asteroid poses a greater threat.

I wish you clear skies and big eyes.

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