An asteroid that whizzed past Earth last week had its own Moon

• An asteroid called 2020 BX12 was closer than the Moon is to Earth as it flew past the blue planet last week.
  
• Images recorded by the Arecibo Observatory show that the asteroid was not alone.
  
• According to the observatory, 2020 BX12’s companion was the asteroid’s own Moon.
  

Asteroids fly past Earth on a daily basis. More often than not, it’s more than one asteroid on any given day. However, last week one of the asteroids that whizzed past the planet had its own Moon.

At a distance of 302,000 kilometres from Earth, asteroid 2020 BX12 was tagged as potentially hazardous. Coming in closer than the Earth’s own Moon, any shift in its predicted path could have resulted in a collision.

The Arecibo Observatory in Puerto Rico recorded the asteroid as it made its close-approach speeding at over 90,000 kilometres per hour - to make sure that there weren’t any unexpected changes in its trajectory. That’s when they detected the asteroid wasn’t alone.


An asteroid with its own Moon
The primary asteroid was around 165 meters in diameter. However, its partner was less than half its size — around 70 meters in diameter, according to estimates. The distance between the two space rocks was less than 360 meters, as per data collected on February 5.

"The movement of the satellite between the two observations, which were made approximately 23 hours apart, suggests a mutual orbital period of 45-50 hours and would be consistent with a tidally locked satellite," said Arecibo’s report.

Asteroids can have more than one Moon
Currently, 2020 BX12 doesn’t pose a danger to Earth and flying further away from the planet as it continues on its orbit. And, it’s not the first asteroid to be reported with a Moon in its orbit.

Many space rocks in the main asteroid belt that lies between Mars and Jupiter have a Moon. Some even have more than one Moon. Out of the 16,4000 known near-earth objects, at least 60 asteroids have Moons.

2020 BX12 is scheduled to fly past Earth in 2022 and 2024. However, it will be nowhere as close to the planet as it was whooshing past the planet between February 4 and 5.

See also:
The 10 biggest asteroids that pose a threat to Earth in 2020

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