The asteroid came from behind the sun, making it impossible for astronomers to see it
An asteroid the size of a refrigerator came within 3000 kilometres of the Earth without scientists knowing.
Asteroid 2021 UA1 is the third-closest asteroid that has ever approached our planet, passing over Antarctica on Sunday at a higher altitude than the International Space Station, but lower than the communication satellites that orbit the Earth.
The celestial object had a diameter of only two meters, meaning that if it had come closer to our planet it would have likely been burned up in our atmosphere.
“The reason the planet’s fly-by was so surprising was because it was behind the sun, coming from the daytime sky, so it was undiscoverable prior to closest approach”, Tony Dunn, an astronomer who runs the website Orbitsimulator, 发推文.
There are only two asteroids that have come closer in Earth’s history: one was asteroid 2020 QG, which came just 1,830 miles over the southern Indian Ocean – but was also small enough not to pose a threat to Earth – and asteroid 2020 VT4, which flew by a few hundred miles away on Friday the 13日.
Although these asteroids are too small to affect the Earth, the possibility of a larger one causing considerable harm to the planet is one that many scientists are preparing for.
The only response would be to evacuate the area before the asteroid hit, however the impact zone was across large parts of North Africa and Europe.
中国人 researchers have considered send more than 20 rockets that could stop a giant asteroid.
China’s National Space Science Centre found in simulations that 23 Long March 5 rockets, which weigh 900 tonnes when they leave the planet, hitting simultaneously could divert an asteroid from its original path by nearly 9,000 kilometres – 1.4 times the Earth’s radius.