Earth has a new companion – and why that’s exciting

Don’t worry: this story is not about the imminent destruction of Earth again. On the contrary: asteroids like 2020 XL5, discovered in 2020, are exciting because they could provide insights into Earth’s early past. 2020 XL5 is a so-called Trojan, as astronomers confirm now in the science magazine Nature (the assumption existed already before): An asteroid which accompanies Earth in its orbit.

If one considers only the system from sun and planet, there are several places, at which the attractive f...