Asteroid trailing behind Mars could possibly be stolen twin of Earth’s Moon


According to, an asteroid caught in the gravitational wake of Mars has been observed in greater detail than ever before, and it reveals a surprising resemblance to our own Moon. This raises some interesting questions about the origins of the object.

The asteroid in question, (101429) 1998 VF31 (hereafter ‘101429’), is part of a group of trojan asteroids sharing the orbit of Mars. Trojans are celestial bodies that fall into gravitationally balanced regions of space, located 60 degrees in front of and behind the planet from the sun. Most of the trojan asteroids we know of share the orbit of Jupiter, but other planets have them too, including Mars and Earth.

What makes this asteroid interesting is that among the Red Planet’s trailing trojans, 101429 appears to be unique. The rest of the group, called the L5 Martian Trojans, all belong to the Eureka family, which consists of 5261 Eureka and a bunch of small fragments believed to come loose from their parent space rock.

A new study led by astronomers from the Armagh Observatory and Planetarium (AOP) in Northern Ireland examined how sunlight reflects off of the Eureka family using a spectrograph.

AOP astrochemist Galin Borisov explained, “The spectrum of this particular asteroid seems to be almost a dead-ringer for parts of the Moon where there is exposed bedrock such as crater interiors and mountains.”

AOP astronomer Apostolos Christou shed some light on how a remnant of our Moon could get trapped in orbit with Mars in a statement. “The early solar system was very different from the place we see today, the space between newly-formed planets was full of debris and collisions were commonplace. Large asteroids [planetesimals] were constantly hitting the Moon and other planets. A shard from such a collision could have reached the orbit of Mars when the planet was still forming and was trapped in its Trojan clouds.”

Researchers say it’s not the only explanation for 101429’s past. It is also possible, and perhaps more likely, that the object could be a result of a similar collision that broke off a fragment of early Mars. It could even just be an asteroid that, through the process of solar radiation, ended up looking just like the Moon. Future observations with more powerful spectrographs might be able to clear up this mystery of space parentage.



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