A city-killing asteroid the size of a major skyscraper will scream past Earth in just hours, and scientists have warned that it could return in the future.

The asteroid 2025 FA22 will come within 520,000 miles of Earth at approximately 3:40am ET early Thursday morning.

That's roughly twice the distance of the Earth to the moon, meaning this particular asteroid poses no immediate threat to the planet.

However, scientists have been aware of this space rock since March and originally warned that it may strike Earth when it passes through this part of the solar system again on September 23, 2089.

Since that initial projection of the asteroid's path around our solar system, the European Space Agency (ESA) has dropped 2025 FA22 from their watchlist of potential cosmic threats after taking more precise measurements of its course.

When astronomers first spotted 2025 FA22 with the Pan-STARRS 2 telescope in Hawaii, the asteroid's large size and regular passes by Earth made it a significant threat for a catastrophic collision.

The asteroid measures between 427 and 951 feet across, nearly as big as New York's famous Chrysler Building.

Based on its current path around the solar system, 2025 FA22 will make close passes by Earth Thursday, in 2089, and again in 2173, when the asteroid is predicted to come within 200,000 miles of Earth.

An artist's impression of an asteroid near Earth. Asteroid 2025 FA22 will come within 520,000 miles of the planet on September 18

If an asteroid the size of 2025 FA22 were to strike the Earth, it could wipe out a major city and everything around it for dozens of miles, like a massive bomb going off.

Such an asteroid impact could cause fires, earthquakes, and tsunamis. If it landed in the ocean, and throw up so much dust that it would block the sun for weeks, disrupting the weather and crops worldwide.

While the ESA has determined that there's no threat to Earth Thursday morning, coming within 520,000 mile of the planet is still considered a 'close approach' in space terms.

This relatively close call is close enough for astronomers to study the rock easily using Earth-based telescopes, like seeing a plane fly over from 100 miles up, not buzzing your rooftop.

The asteroid has been screaming through space at about 24,000 miles per hour. To put that in perspective, it could cross the entire US in under 15 minutes.

You won't be able to see 2025 FA22 with the naked eye because it's too dim and far away for that.

However, a backyard telescope with a lens at least eight inches wide or strong stargazing binoculars should be able to pick it up.

It'll look like a faint, moving dot against the stars during its closest approach at 3:41am ET.

Asteroid 2025 FA22 will make its close approach to Earth (blue orbit circle) around 3:40am ET on September 18. It will return in 2089 and 2173

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The Virtual Telescope Project has also set up a free livestream starting Wednesday night at 11pm ET which runs through 2025 FA22's entire flyby.

Although the ESA has maintained that there's no threat from 2025 FA22 this year, scientists with the space agency are preparing to use Thursday's close call as a practice run for future threats from asteroids.

As part of the 2025 FA22 Campaign, ESA researchers will measure exactly where the asteroid is, how it moves, and how bright it looks in the sky.

A team led by ESA's Maxime Devogele has also been tracking how sunlight bounces off the asteroid's surface.

This helps astronomers figure out what the asteroid is made of, such as having a rocky or metallic composition, how rough or smooth it is, and how reflective it is.

All of the data scientists pull from 2025 FA22 this month could help humans figure out how to deflect or destroy asteroids on a collision course with Earth in the future.

Asteroid the size of a skyscraper headed toward Earth in just HOURS