An asteroid, named 2023 BU, the size of a large truck, is set to make one of the closest ever recorded approaches to Earth on Thursday. Scientists have calculated that the asteroid will fly by Earth at a distance of just 2,200 miles above the planet’s surface. The asteroid, which poses no danger to the planet, will travel over the Pacific Ocean west of southern Chile in the afternoon Pacific time.
According to Davide Farnocchia, a navigation engineer at NASA’s Jet Propulsion Laboratory, this is the fourth-closest approach recorded and he stated that there were two instances in 2020 and another in 2021. 2023 BU was first spotted by amateur astronomer Gennadiy Borisov from his observatory in Nauchnyi, Crimea, on January 21st. More observations were reported to the Minor Planet Center, a clearinghouse for the position measurement of small celestial bodies. And after the discovery was announced, observatories around the globe added to the findings, helping astronomers refine 2023 BU’s orbit, according to NASA.
NASA’s impact hazard assessment system, Scout, analyzed the data and quickly predicted the near miss. Dr. Farnocchia, who developed Scout, received an alert from Scout about the asteroid while he was having dinner. “When you see that alert, you just want to make sure that it’s real,” he said. “So usually I just go and see the data and confirm it’s real and that everything is checked out.”
Scientists use perihelion—or the point in the orbit of a plane, asteroid or comet at which it is closest to the sun—to measure how close an object is getting to Earth. If the perihelion of an object is less than 1.3 astronomical units, which is the distance between Earth and the sun, it is called a near-Earth object.
“Some of them actually can come really close to the Earth, and some of them might never come close to the Earth. That is just the first cutoff to split objects that could be potentially interesting and the ones that certainly are not,” said Dr. Farnocchia.
Any asteroid in Earth’s proximity and gravity can experience a change in trajectory. 2023 BU’s orbit around the sun was expected to take 359 days and follow a circular path, NASA said. But after its expected encounter with Earth on Thursday, its orbit will become more elongated, and one orbit will take 425 days.
Dr. Farnocchia also added that discovering smaller objects is a way to keep an eye on bigger discoveries, like NASA’s DART mission in 2022. The space agency used its fast-moving spacecraft to shift the orbit of a distant asteroid after colliding with it. “Besides discovering objects, we are also making preparations to be able to deflect them in case that was ever needed,” said Dr. Farnocchia. “The DART mission is a great example of that.”