There are many conspiracy theories that point to the existence of a planet on the far side of the sun that orbits the Earth. Although this is impossible, celestial mechanics allows several celestial bodies to rotate around the same orbit under certain conditions. The Trojan asteroids orbiting Jupiter and Earth are excellent examples of this. Astronomers have now found the first example in another solar system.
The PDS 70 star system is quite young and we know for sure that it contains two planets, PDS 70b and PDS 70c. Located 400 light-years away, both planets are thought to be gas giants similar to Jupiter. In the orbit of PDS 70b, astronomers have detected a large debris cloud, a possible sign of planet formation or the remnants of a planet that has already formed.
Two decades ago, one theory predicted that pairs of planets of similar mass, known as Trojans or companion planets, would orbit their star in the same orbit. “For the first time we have found evidence for this idea,” lead author Olga Balsalobre-Rosa, a student at the Center for Astrobiology in Madrid, said in the announcement. IFLScience.
Sightings of the phenomenon aren’t rare, but it wasn’t about the planets
Trojan asteroids are rocky bodies that orbit in the same orbit as a planet. Jupiter has more than 4,800, which are divided into two groups. One precedes the gas giant, the other follows it. Earth has a total of two. Jupiter is located near the Lagrangian points L4 and L5, 60 degrees in front of and behind the planet in the same orbit. The debris cloud in the PDS 70 system is also located in one of these regions, and astronomers think they are observing a kind of extrasolar Trojan state where an object twice the size of the moon is forming.
“Exotrojans, that is, Trojan planets outside the solar system, have been like unicorns until now. According to theory, they could exist, but no one has discovered them yet,” said co-author Jorge Lelo Box, senior researcher at the Center for Astrobiology.
In this system, the two possible objects have very different masses, and their orbits are as far from their star as Uranus is from the Sun. But it is possible that there are smaller planets orbiting close to their stars, opening up entirely new possibilities for what worlds (and possibly life forms) might exist out there.
“Who can imagine two worlds with the same length of year and habitable conditions? Our work is the first evidence that such worlds can exist,” Balsallubri-Rosa explained.
We can imagine that a planet could share an orbit with thousands of asteroids like Jupiter, but it is puzzling to me that planets can share the same orbit.
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