On January 26, 2023, a small asteroid called 2023 BU passed very close to Earth: only about 3,600 kilometers from the surface.
Asteroid 2023 BU is about the size of a truck. The distance to which it approached the Earth is one of the smallest of all the approaches of other stars to the Earth to date. Those 3,600 kilometers are in fact one tenth of the distance that geosynchronous satellites orbit around the Earth.
There was no risk of the asteroid hitting Earth. But even if it had fallen towards it, this small asteroid, about the size of a truck, would have turned into a ball of fire and most of it would have broken up harmlessly in the atmosphere. Only some of the larger pieces could have fallen as small meteorites.
The asteroid was discovered by amateur astronomer Gennadiy Borisov, discoverer of the interstellar comet 2I/Borisov, from his MARGO observatory in Nauchnyi (Crimea), on Saturday, January 21. More observations were reported to the MPC (Minor Planet Center), the international body that manages position measurements of small celestial bodies, and the data was automatically published on the Near-Earth Object Confirmation page. After collecting enough observations, the MPC announced the discovery. In three days, dozens of observations were made by various observatories around the world, helping astronomers to better refine the prediction of the orbit that 2023 BU would follow.
The Scout impact risk assessment system, managed by a NASA center, analyzed the data from the MPC confirmation page and quickly predicted the passage of the asteroid near Earth. That center, the CNEOS (Center for Near Earth Object Studies) calculates all known orbits of near-Earth asteroids to provide assessments of possible impact risks in support of NASA’s PDCO (Planetary Defense Coordination Office). .
“Scout quickly ruled out 2023 BU as an impactor, but despite the few observations, he was able to predict that the asteroid would come extraordinarily close to Earth,” said Davide Farnocchia, a navigation engineer at the Jet Propulsion Laboratory (JPL). of NASA who developed the Scout system. “In fact, this is one of the closest close-ups yet of such an object.”
The trajectory of the asteroid 2023 BU, in red. Observe the drastic deviation that it suffers as a consequence of the Earth’s gravity. The orbit of the geosynchronous satellites is shown in green and the orbit of the Moon is represented by a gray oval. (Image: NASA JPL/Caltech)
While any asteroid in the vicinity of Earth experiences a change in its path due to our planet’s gravity, 2023 BU came so close that its path around the Sun has been significantly altered. Before meeting Earth, the asteroid took 359 days to complete its orbit around the Sun, and that orbit was roughly circular. After its encounter, the asteroid’s orbit has become more elongated, moving roughly halfway between the orbits of Earth and Mars at its farthest point from the Sun. The asteroid is estimated to take 425 days from now to make a complete revolution around the Sun. (Source: NASA)