
This orbital diagram from CNEOS’ Close Approach Viewer shows the trajectory of 2023 BU — in red — during its close approach to Earth on January 26, 2023. The asteroid will fly about 10 times closer to Earth than the orbit of geostationary satellites that are shown in the green line. Photo credit: NASA
About the size of a panel van, asteroid 2023 BU is expected to be one of the closest approaches to a near-Earth object on record.
On Thursday, January 26th, a small near-Earth asteroid will come very close to our planet. Designated 2023 BU, the asteroid will zoom over the southern tip of South America at approximately 4:27 p.m. PST (7:27 p.m. EST), just 2,200 miles (3,600 kilometers) above the planet’s surface and well within the orbit of geostationary satellites.
There is no risk of the asteroid hitting Earth. But even if it did, this small asteroid — estimated to be 12 to 28 feet in diameter — would turn into a fireball and decay largely harmlessly in the atmosphere, with some of the larger debris potentially falling as small meteorites would.
The asteroid was spotted on Saturday, January 21 by amateur astronomer Gennadiy Borisov, discoverer of the interstellar comet 2I/Borisov, from his MARGO observatory in Nauchnyi, Crimea. Other observations were reported to the Minor Planet Center (MPC) – the international recognized clearing house for position measurements of small celestial bodies – and the data was then automatically published on the Near Earth Objects confirmation page. After gathering enough observations, the MPC announced the discovery. In three days, a number of observatories around the world had made dozens of observations, helping astronomers better refine 2023 BU’s orbit.

This view from NASA’s Scout system shows the deflection in the trajectory of asteroid 2023 BU – in red – caused by Earth’s gravity. The orbit of geosynchronous satellites is shown in green, and the moon’s orbit is shown by the gray oval. Photo credit: NASA
NASA’s Scout hazard assessment system, maintained by the Center for Near Earth Object Studies (CNEOS) at the agency’s Jet Propulsion Laboratory in Southern California, analyzed the data from the MPC’s confirmation page and quickly predicted the near miss. CNEOS computes every known low-Earth orbit of asteroids to provide potential impact hazard assessments in support of NASA’s Planetary Defense Coordination Office (PDCO).
“Scout quickly ruled out 2023 BU as an impactor, but despite the very few observations it was still able to predict that the asteroid would make an exceptionally close approach to Earth,” said Davide Farnocchia, a navigation engineer at JPL who developed Scout. “In fact, this is one of the closest approaches of a known near-Earth object ever recorded.”
While every asteroid near Earth will experience a change in its trajectory due to our planet’s gravity, 2023 BU will come so close that it is expected to change its orbit around the Sun significantly. Before encountering Earth, the asteroid’s orbit around the Sun was roughly circular and approaching Earth’s orbit, taking 359 days to complete its orbit around the Sun. After its encounter, the asteroid’s orbit will lengthen, bringing 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.
More information:
For more information on CNEOS, asteroids and near-Earth objects, visit: https://www.jpl.nasa.gov/asteroid-watch
Citation: NASA system predicts small asteroid to pass close to Earth this week (2023, January 25) Retrieved January 25, 2023 from https://phys.org/news/2023-01-nasa-small- asteroid-earth-week.html
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