In very few cases has it been possible to warn of an asteroid impact and its impact location has been calculated before it occurred. In particular, it has happened only three times.
The first event was the impact of the 2008 asteroid TC3, which lit the sky before dawn over northern Sudan on October 7, 2008. The second was the asteroid 2014 AA, which was discovered a few hours before the impact on 1 January 2014 in the Atlantic Ocean. The third was this Saturday of June.
Impact in Africa
The asteroid was only about 2 meters wide, which is small enough to safely disintegrate in the Earth’s atmosphere, and was discovered on June 2, determining that it was in the process of colliding with Earth.
Appointed 2018 LA, the asteroid was discovered by Catalina Sky Survey, funded by NASA, located near Tucson and operated by the University of Arizona. It entered the atmosphere of the Earth at a speed of 17 kilometers per second at 16.44 UTC, and disintegrated several kilometers above the surface, creating a bright fireball.
Although the event was only planned a few hours before it happened, it was witnessed by several observers and was captured on a webcam:
Given that it was determined that the asteroid was very small and, therefore, harmless, NASA did not issue more impact alerts. However, the exercise served as a test to face more important threats, explains Lindley Johnson, Planetary Defense Officer at NASA Headquarters:
This real-world event allows us to exercise our capabilities and gives some confidence that our impact prediction models are adequate to respond to the potential impact of a larger object.
Each day, Earth receives around 100 tons of extraterrestrial matter in the form of dust grains. 99% of these grains have an approximate size of between 0.05 and 0.5 millimeters. In addition, our planet is bombarded by objects of dimensions between the decimeter and the meter: around 10 tons of meteorites per year.