An asteroid the size of a large truck will fly past Earth on Thursday just 2,200 miles above the planet’s surface, scientists said.
The asteroid, named 2023 BU, will travel over the Pacific Ocean west of southern Chile on Thursday afternoon Pacific Time, according to David Farnocchia, a navigation engineer at the National Aeronautics and Space Administration’s Jet Propulsion Laboratory.
There is no threat from the near-Earth object, and no expected effects.
“It’s not going to break,” Dr. Farnocchia said. “It’s going to zoom past Earth, say hello and move on.”
If it entered Earth’s orbit, the asteroid would burn up upon entry and turn into a ball of fire in its small size. “It’s not going to be close enough for him,” Dr. Farnocchia said.
According to Dr. Farnocchia, this will be the fourth-closest approach ever recorded. He said that two incidents happened in 2020 and one more in 2021.
Asteroids are large rocks and are harder to spot than comets, which usually have spectacular tails.
2023 BU was first observed by amateur astronomer Gennady Borisov on 21 January from his observatory in Nauchny, Crimea. More observations were reported to the Minor Planet Center, a clearinghouse for position measurements of small celestial bodies. And after the discovery was announced, observatories around the world added to the findings, helping astronomers refine 2023 BU’s orbit, according to NASA.
NASA’s Impact Hazard Assessment System, which is based in Southern California and called Scout, analyzed the data and predicted the near miss.
Dr. Farnocchia, who developed Scout, said he received an asteroid alert from Scout while he was eating dinner. “When you see that alert, you just want to make sure it’s real,” he said.
Scientists use perihelion – or the point in the orbit of an asteroid, asteroid or comet at which it is closest to the Sun – to measure how close an object is getting to Earth. If an object’s perihelion is less than 1.3 astronomical units, which is the distance between the Earth and the Sun, it is called a near-Earth object.
“Some of them may come really close to Earth, and some of them may never come close to Earth. This is only the first cutoff for dividing objects that could be potentially interesting and that certainly are not,” Dr. Farnocchia said.
Any asteroid in proximity to Earth and in gravity can experience a change in trajectory. NASA said that 2023 BU’s orbit around the Sun was expected to take 359 days and follow a circular path. But after its expected encounter with Earth on Thursday, its orbit will be longer, and one orbit will take 425 days.
About 100 tonnes of material from space falls to Earth every day, although most of it is small. Objects a few meters in size reach Earth about once a year and cause no harm. Dr. Farnocchia said large objects that could cause damage could happen in our lifetime. “So the thing you have to do is find as many as you can,” he said.
Astronomers measure some space objects such as asteroids by looking at their brightness, which gives them an idea of their mass. The 2023 BU is estimated to be between 3.5 meters and 8 meters, or 11.5 feet to 28 feet—about the size of a large truck.
Searching for smaller objects is one way of tracking larger discoveries, such as NASA’s DART mission in 2022. The space agency used its high-speed spacecraft to shift its orbit after hitting a distant asteroid.
“In addition to discovering the objects, we are also preparing to be able to deflect them if needed,” Dr. Farnocchia said. The Dart mission is a great example of this.