A photo of Jupiter in the year 2000, and its nearest moon Io.
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NASA / AFP
NASA was surprised to spot a celestial body resembling a comet in an area of the solar system where no such object had ever been detected.
The US space agency described him on its blog as an “unexpected visitor” because he is in the region between Neptune and Jupiter, but closer to the latter.
The comet was named LD2, said a study published Feb. 11 in
The Astonomical Journal
.
It was observed in the middle of Jupiter's Trojan asteroids, which are a cluster of rocks revolving around the Sun at the same time as "the giant".
The object is made of ice and belongs to the category of centaurs, small meteors well known to scientists in this region of space.
When their path brings them closer to the sun, they heat up and take on an appearance close to that of a comet.
First observed in 2019
An image of LD2 indeed shows that the object shows traces of degassing and has a tail as well as a halo made up of dust and gas.
Researchers now want to understand how the celestial body ended up in this unusual location after being attracted by Jupiter's force of gravity.
They estimated that at one point in its journey, LD2 must have passed very close to the planet and then remained trapped among its Trojan asteroids.
Computer simulations estimated that the object had rubbed shoulders with the most massive of the planets in the solar system about two years ago.
The comet was first observed in June 2019, prompting astronomers to study the previous photos.
An image of LD2 dating from two months earlier was then discovered.
Scientists then used Hubble to get a better photo.
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