Earth being followed by a ‘Trojan asteroid’, scientists confirm

‘2020 XL5’ is only the second such object ever discovered

Earth is being followed by a “Trojan asteroid”, scientists have confirmed.

It is only the second such object ever discovered – and a much more promising specimen than the previous one, researchers say.

What’s more, humans may one day be able to visit the rock, settling “human bases” there, researchers say.

Trojan asteroids share their orbit with a planet. The small objects stay in a stable orbit just ahead of or behind the world that they are attached to.

They have been found a number of times in the past, and take their name from those that were first found around Jupiter, where they are named after figures from the Trojan War.

But barely any have ever been spotted in Earth. Only one, known as 2010 TK₇, has ever been definitively found before.

On December 12, 2020, however, scientists spotted an intriguing target. Early observations suggested it was another Earth Trojan, but it was hard to verify – with few observations, it was hard to know for sure where its orbit went.

Now researchers have detailed that orbit by combining data from archives with observations conducted from Earth. That work confirms that the object is actually an Earth Trojan, as suspected.

It still remains unclear where exactly it came from. It might have begun its life in the main asteroid belt further out in the solar system, and been thrown out when it interacted with Jupiter’s gravity, but that remains unclear.

Scientists do know where the object is going, however, if not where it came from. Observations suggest the orbit means it will stay in its current orbit for another 4,000 years.

It also appears to be a C-complex type asteroid, made up mostly of carbon.

The new asteroid, known as 2020 XL₅, is also bigger than its predecessor, as well as being able to visit with less fuel needed.

“Therefore these objects may become ideal targets for space missions and, in the more distant future, to settle human bases or install scientific hardware that would benefit from their peculiar location,” the authors write.

They detail that research in a new study, ‘Orbital stability analysis and photometric characterization of the second Earth Trojan asteroid 2020 XL5’, published in Nature Communications.