The Minor Planet Centre has just announced that the Earth has been orbited by a second moon for the past three years or so. Yes, really. Here’s everything you need to know.
So, Earth has a new moon. While excitement about the discovery is growing, it is important to keep in mind that this moon isn’t as impressive as our main satellite. It is extremely faint – it is estimated to be only between one and six metres across – and won’t be with us for much longer.
Subsequent observations enabled its orbit to be calculated, and at 22:53 Universal Time (UT) on February 25, the Minor Planet Center announced the discovery, designating it as 2020 CD₃ and confirming that it is temporarily bound to the Earth.
The object 2020 CD₃ is essentially just a tiny member of a class of asteroids whose orbits cross the Earth’s orbit. Occasionally, they come near or collide with the Earth, but in this case a collision would not have been a catastrophe for us because 2020 CD₃ is so small that it would have broken up in the atmosphere before reaching the ground.
Instead of colliding with our planet, however, the initial approach of 2020 CD₃ towards the Earth meant that it was captured into orbit at a somewhat greater distance than our much larger, permanent moon.