Space rock to pass closer than some satellites

Graph showing the trajectories of asteroid 2023 BU and the orbit of common satellites around the Earth.

You definitely shouldn’t panic, but there is a large asteroid about to pass close to Earth in the next few hours.

About the size of a bus, the space rock, known as 2023 BU, will fly over the southern tip of South America shortly after midnight GMT.

With an expected maximum approach of 3,600 km (2,200 miles), it counts as one close shave.

And it illustrates how there are still significantly sized asteroids lurking near Earth that have yet to be detected.

This was gathered just last weekend by amateur astronomer Gennadiy Borisov, who operates out of Nauchnyi in Crimea, the peninsula that Russia wrested from Ukraine in 2014.

Follow-up observations have refined what we know about BU 2023’s size and, more importantly, its orbit.

That’s how astronomers can be so sure it will miss the planet, even as it enters the arc occupied by the world’s telecommunications satellites, which are 36,000 km (22,000 miles) above us.

The chances of hitting a satellite are very, very slim.

The time of the lowest altitude is calculated at 7:27 pm EST on Thursday; 00:27 GMT on Friday.

Even if BU 2023 were on a direct collision course, it would struggle to do much damage.

With an estimated size of 3.5 m to 8.5 m in diameter (11.5 ft to 28 ft), the rock would likely disintegrate high in the atmosphere. However it would produce a spectacular fireball.

For comparison, the famous Chelyabinsk meteor that entered Earth’s atmosphere over southern Russia in 2013 was an object about 20 meters in diameter. It produced a blast wave that shattered windows to the ground.

Scientists at the US space agency NASA say BU 2023’s orbit around the Sun will be changed by its encounter with Earth.

Our planet’s gravity will pull it and adjust its path through space.

“Before encountering Earth, the asteroid’s orbit around the Sun was roughly circular, approximating Earth’s orbit, taking 359 days to complete its orbit around the Sun,” the agency said in a statement.

“After its encounter, the asteroid’s orbit will be more elongated, moving it about halfway between the orbits of Earth and Mars at its farthest point from the Sun. The asteroid will then complete one orbit every 425 days.”

There is a major effort underway to find the much larger asteroids that could actually do damage if they were to hit Earth.

Graph: Asteroid populations

Graph: Asteroid populations

The real monsters out there, like the 12km wide rock that wiped out the dinosaurs, have probably all been spotted and are no cause for concern. But you reduce the size to something that is, say, 150 meters in diameter and our inventory has gaps.

Statistics indicate that perhaps only about 40% of these asteroids have been seen and evaluated to determine the level of threat they might pose.

Such objects would inflict city-scale devastation if they were to hit the ground.

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