Below is the list of asteroids that have come close to Earth in 2023.
A list of known near-Earth asteroid close approaches less than 1 lunar distance () from Earth in 2023, based on the close approach database of the Center for Near-Earth Object Studies (CNEOS).
For reference, the radius of Earth is about . Geosynchronous satellites have an orbit with semi-major axis length of .
The closest approach of Earth by an asteroid in 2023 was that of , an asteroid with a diameter of , at from the center of the Earth, or about above its surface. The largest asteroid to pass within 1 LD of Earth in 2023 was at in diameter, for an absolute magnitude of 24.3. The fastest asteroid to pass within 1 LD of Earth in 2023 was that passed Earth with a velocity with respect to Earth of , while the slowest bypass within lunar distance was that of at a velocity with respect to Earth of .
As most asteroids passing within a lunar distance are less than 40 meters in diameter, they generally are not detected until they are within several million kilometres of Earth. Objects coming from the direction of the Sun may not be publicly announced until a few days after closest approach. For example, was first imaged six hours after closest approach, then confirmed by other observations, but not officially announced until 3.5 days after closest approach. that approached from the direction of the Sun was not first observed until 3.6 days after closest approach. The largest asteroid on this list that is riskâÂÂlisted is at about 17 meters in diameter with a 3.5-day observation arc and a 1: chance of Earth impact on 24 September 2118.
The CNEOS database of close approaches lists some close approaches a full orbit or more before the discovery of the object, derived by orbit calculation. The list below only includes close approaches that are evidenced by observations, thus the pre-discovery close approaches would only be included if the object was found by precovery, but there was no such close approach in 2023.
This list and relevant databases do not consider impacts as close approaches, thus this list does not include , an asteroid which was predicted to impact on Earth and burned up in its atmosphere, as well as several more objects that collided with Earth's atmosphere in 2023 which weren't discovered in advance, but were observed visually or recorded by infrasound sensors designed to detect detonation of nuclear devices.
This sub-section visualises the warning times of the close approaches listed in the above table, depending on the size of the asteroid. The sizes of the charts show the relative sizes of the asteroids to scale. For comparison, the approximate size of a person is also shown. This is based the absolute magnitude of each asteroid, an approximate measure of size based on brightness.
Absolute magnitude H âÂÂ¥ 30 (smallest) (size of a person for comparison)
Absolute magnitude 30 > H âÂÂ¥ 29
Absolute magnitude 29 > H âÂÂ¥ 28
Absolute magnitude 28 > H âÂÂ¥ 27
Absolute magnitude 27 > H âÂÂ¥ 26
Absolute magnitude 26 > H âÂÂ¥ 25
Absolute magnitude 25 > H (largest)
Below is an example list of near-Earth asteroids that nominally will pass more than 1 lunar distance (384,400 km or 0.00256 AU) from Earth in 2023. During 2022, over 1,000 asteroids passed within of Earth.