List of asteroid close approaches to Earth in 2021

Below is the list of asteroids that have come close to Earth in 2021.

Timeline of known close approaches less than one lunar distance from Earth
A list of known near-Earth asteroid close approaches less than 1 lunar distance (0.0025696 AU) from Earth in 2021.

For reference, the radius of Earth is about 0.0000426 AU or 0.0166 lunar distances. Geosynchronous satellites have an orbit with semi-major axis length of 0.000282 AU or 0.110 lunar distances.

The largest asteroid to pass within 1 LD of Earth in 2021 was with an estimated diameter of around 68 meters and an absolute magnitude of 24.0. The fastest asteroid to pass within 1 LD of Earth in 2021 was that passed Earth with a velocity with respect to Earth of 27.7 km/s.

Warning times by size
This sub-section visualises the warning times of the close approaches listed in the above table, depending on the size of the asteroid. It shows the effectiveness of asteroid warning systems at detecting close approaches in 2021. 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 30 and greater (size of a person for comparison)

Absolute magnitude 29-30

Absolute magnitude 28-29

Absolute magnitude 27-28

Absolute magnitude 26-27 (probable size of the Chelyabinsk meteor)

Absolute magnitude 25-26 Absolute magnitude less than 25 (largest)

Predicted close approaches
Below is the list of predicted close approaches of near-Earth asteroids larger than magnitude 27, that were predicted to occur in 2021. This relates to the effectiveness of asteroid cataloging systems at predicting close approaches in 2021. (with a 9 day observation arc from January 2018) could have passed as far as 3 e6km from Earth.

For asteroids which were observed but not predicted in advance, see the main list above.

Additional examples


Below is an example list of near-Earth asteroids that passed or will pass more than 1 lunar distance (384,400 km or 0.00256 AU) from Earth in 2021.