The National Science Foundation’s NSF’s National Optical-Infrared Astronomy Research Laboratory (NOIRLab) recently reported that the Southern Astrophysical Research (SOAR) Telescope in Chile confirmed asteroid 2020 XL5 is in fact a second and the largest Trojan asteroid accompanying the Earth. “Trojan” means that the asteroid orbits the Sun along the same path as the Earth. The first discovered Trojan asteroid is called 2010 TK7, which is about 400 meters in diameter. The new asteroid 2020 XL5 is about 1.2 kilometers in diameter.
The Earth may have more than just two of these Trojan asteroids, so stay tuned. But we are not unique. Jupiter has more than 5,000 of them. Trojan asteroids are found at Lagrange point 4 (L4) and L5 (see graphic below). Both the the Trojans asteroids mentioned above are located in L4.
These companion asteroids could also be useful in the future. Cesar Briceño of NOIRLab stated:
If we are able to discover more Earth Trojans, and if some of them can have orbits with lower inclinations, they might become cheaper to reach than our Moon…So they might become ideal bases for an advanced exploration of the Solar System, or they could even be a source of resources.
Extra: To learn what else you can find at these Lagrange points, see my earlier post.