Trojan asteroids share the same orbital path as some planets, leading in front of the planet or trailing behind., but Mars also has some. One of these Martian companions – the asteroid (101429) 1998 VF31 – could be a double for our moon.
A team led by researchers from the Armagh Observatory and Planetarium (AOP) in Northern Ireland has taken a close look at the composition of asteroid 101429 and has drawn some fascinating connections to our lunar neighbor in a study set for the January issue. 2021 of Icarus magazine and published online 1 August.
Planetary scientists used the X-shooter spectrograph on the Very Large Telescope at the European Southern Observatory in Chile to observe how sunlight reflects off the asteroid’s surface. They analyzed this data and compared it with other known space bodies.
Early observations of the asteroid, which lies behind Mars on the same orbital path, led the team to think it might have a similar composition to a common type of meteorite. “To their surprise, they found that the best spectral match was not with other small bodies but with our closest neighbor, the moon,” lead author Apostolos Christou said in an AOP statement on Tuesday.
Study co-author Galin Borisov with AOP described asteroid 101429 as a “dead ring for parts of the moon where bedrock is present such as the interior of the crater and mountains.”
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So what’s the story of the asteroid’s origin? The researchers proposed several options. After all, it may be similar to ordinary meteorites, but it has simply been worn down by its space adventures over time.
It could be a piece of the moon. Christou described the first solar system filled with debris when the moon was hit by large asteroids: “A fragment of such a collision could have reached the orbit of Mars when the planet was still forming and was trapped in its Trojan clouds”, he She said.
A third idea is that the asteroid was shot down by Mars through a similar impact scenario. Christou described this concept as “perhaps more likely”.
The asteroid remains an open mystery, but if the moon needs a stunt double for a few days, we know who to call.