Astronomers confirm 2020 XL5 as second known Earth Trojan asteroid

Astronomers have confirmed "2020 XL5" as the second known Earth Trojan asteroid, small bodies that share Earth's orbit and which may have been trapped there during the formation of our planet. The first Earth Trojan - 2010 TK7 - was discovered over a decade ago.

The paper presenting the discovery of the second Earth asteroid was published on February 1, 2022, in Nature Communications. Toni Santana-Ros (TSR) from the University of Alicante and Institute of Cosmos Sciences of the University of Barcelona, is the lead author of the paper. The research was supported by the European Space Agency's Near-Earth Object Coordination Centre (NEOCC).

According to lead author TSR, 2020 XL5 is a “transient” Trojan asteroid that won’t remain an Earth Trojan forever. Astronomers predict that in about 4000 years, it will leave Earth’s Lagrange point – possibly ending up on a highly elliptical orbit around the Sun-like many other asteroids.

For the unversed, Lagrange points are the regions of space where the gravitational pull from the Sun and one of the planets is balanced.

"This discovery strongly encourages us to keep searching for new Earth Trojans. Finding an Earth Trojan made of material leftover from Earth's formation would be incredibly helpful for unravelling many secrets of the early Solar System," says TSR.

The second ever #asteroid of its kind!🥈☄️Astronomers have confirmed that 2020 XL5 is the second known “Earth Trojan”.https://t.co/i6mof1AEkb📷 @NOIRLabAstro /SF/AURA/J. da Silva/Spaceengine pic.twitter.com/KbW8mDuN48

— ESA Operations (@esaoperations) February 1, 2022

Speaking of the threat posed by the second known Earth Trojan, Laura Faggioli (LF) from ESA's NEOCC explains that 2020 XL5 is roughly 1 km wide, which is a significant size for an asteroid. However, the asteroid's home at the Lagrange point is roughly as far from Earth as the Sun, and its orbit will keep it that far away for thousands of years.