A Second Trojan Asteroid Discovered Sharing Earth’s Orbit

A new study published on Tuesday has revealed the existence of an Earth Trojan asteroid, only the second of its kind to be discovered.

Astronomers found asteroid 2020 XL5 while operating the Southern Astrophysical Research Telescope in Chile. The team has now published their study on the discovery in Nature Communications.

“Trojans are objects sharing an orbit with a planet, clustered around one of two special gravitationally balanced areas along the orbit of the planet known as Lagrange points,” wrote study co-author Cesar Briceño in a statement.

Lead study author Toni Santana-Ros explained that Lagrange points indicate the parts of space where both the sun and a planet’s gravitational pull are equally balanced.

“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,” Briceño added. “So they might become ideal bases for an advanced exploration of the Solar System, or they could even be a source of resources.”

This asteroid is larger than the first Earth Trojan, 2010 TK7, which is nearly three times smaller than 2020 XL5. Astronomers first saw the asteroid on December 12, 2020, from a telescope located in Hawaii. They then re-located the asteroid with other telescopes to study it closer.

Trojan asteroids get their name from ancient Greece

Trojan asteroids are named in honor of ancient Greece in reference to the Trojan war. Trojans are small celestial bodies, typically asteroids, that move in the same orbit as larger objects, and are thus co-orbital.

The name was coined by Italian-French mathematician and astronomer Joseph-Louis Lagrange in 1772. Since his initial discovery, each new Trojan is typically named after specific figures from the Trojan war, like Achilles, Hektor, and Patroclus.

The Trojan asteroids that share the planet Jupiter’s orbit around the sun, known as the JupiterTtrojans, have become the subject of attention recently as NASA launched their Lucy mission to study the Jupiter Trojans up-close.

The spacecraft will reach the asteroids by 2027, and provide the first in-depth, up-close look at the Trojans. Scientists are hoping that the information gleaned from the fly-bys will provide them with a better understanding of the infancy of our solar system.

“I’ve been dreaming of sending a spacecraft to the Trojan asteroids for more than a decade,” Cathy Olkin, Lucy’s deputy principal investigator told Space.com. “This opportunity is just outstanding.”

Although scientists have identified the Trojan asteroids from Earth, they are incapable of deriving any detailed images of the objects without conducting a fly-by mission such as Lucy’s. The information these asteroids could provide would potentially revolutionize scientists’ understanding of how the Milky Way formed, helping to piece together the reasons why certain planets have formed in areas of the galaxy that seem inexplicable.