Asteroids seen before impact
Since 2008, telescopes have caught more than a dozen small asteroids hours before they hit.
Key facts
- When
- 2008 to the present
- Where
- Worldwide
- What hit
- all so far less than about 10 m across
- Era
- The sensor age, 2000 onwards
Each from a few tonnes up to a few kilotons of TNT.
Harmless so far, but every one is a rehearsal for finding a dangerous object in time.
What happened
Until 2008 no one had ever seen an asteroid in space and then watched it hit Earth. Now it happens more than once a year. Survey telescopes scanning the sky for near-Earth objects sometimes pick up a very small one only hours before impact, and astronomers can predict where it will come down.
The first was 2008 TC3 over Sudan in October 2008. It was followed by 2014 AA, which fell into the Atlantic at the start of January 2014; 2018 LA over Botswana in June 2018; 2019 MO south of Puerto Rico in June 2019; 2022 EB5 near Jan Mayen in the Arctic Ocean in March 2022; 2022 WJ1 over southern Ontario in November 2022; 2023 CX1 over Normandy in February 2023; and 2024 BX1 near Berlin in January 2024. Three more came in late 2024: 2024 RW1 over the Philippines in September, 2024 UQ over the Pacific in October, and 2024 XA1 over eastern Siberia in December. More have followed since.
When one falls over land, teams now head out to search, and meteorites have been recovered from several, giving rocks whose orbit in space is known exactly.
Effects
None of these has caused harm. They were all small enough to break up or burn up in the atmosphere.
The evidence
Telescope observations before impact, then fireball videos, satellite and infrasound records and, for some, meteorites on the ground.
Did you know?
Most of these discoveries were made by just a few survey telescopes in Arizona, Hawaii and Hungary.
Larger asteroids are much easier to find, and most of those over 1 km across are already known.
Related pages
How is impact energy measured? See energy explained, or try the impact calculator.