Earth Is Followed by a Second Trojan Asteroid, Scientists Say

Speculations about a second Trojan asteroid sharing Earth’s orbit have come to an end. Researchers have confirmed that it’s indeed real. Astronomers believed they had discovered a second Trojan asteroid orbiting Earth in 2020, which sparked rounds of speculation. Scientists affirm that the first confirmed Trojan asteroid isn’t an exceptional case after the most recent updates. Trojan asteroids are tiny space rocks that circle around their host in a shared orbit with a planet. Asteroids of this type have been discovered orbiting other planets in the solar system. However, until now, the asteroid 2010 TK7 was thought to be the sole Trojan asteroid to orbit the Sun alongside Earth.

Now, 2020 XL5 has joined the group. 2020 XL5 measures about 1.2km across and is almost three times longer than 2010 TK7. Scientists are sure that the newly discovered companion of Earth will remain in the same orbit for at least 3,500 more years.

The asteroid 2020 XL5 was first spotted on December 2020 by astronomers with the Pan-STARRS 1 survey telescope in Hawaii. Then, 2020 XL5 was added to the International Astronomical Union’s Minor Planet Center database.

Toni Santana-Ros, the lead author of the study, told Space.com that the finding of 2020 XL5 as an Earth Trojan confirmed that 2010 TK7 was not an exception. This discovery prompts astronomers to search for more Earth Trojans, particularly the first of their kind.

After 2020 XL5 was spotted, astronomer Tony Dunn calculated the object’s trajectory using NASA’s JPL-Horizon’s software. The calculations showed that the object orbits the fourth Earth-Sun Lagrange Point or L4, which is a gravitationally balanced region around our planet and the star. Incidentally, Trojan asteroid 2010 TK7 is also at L4.

Co-author Cesar Briceño, a researcher at the National Science Foundation’s National Optical-Infrared Astronomy Research Laboratory (NOIRLab), said in a statement, “These were very challenging observations, requiring the telescope to track correctly at its lowest elevation limit, as the object was very low on the western horizon at dawn.”

Using archival data from SOAR (Southern Astrophysical Research) and equipment like the SOAR Telescope in Chile, the Lowell Discovery Telescope in Arizona and the European Space Agency’s Optical Ground Station in Tenerife in the Canary Islands, scientists first noted that 2020 XL5 was a C-type asteroid and then confirmed it was an Earth Trojan.