A Mysterious, Undetected Force Is Influencing the Orbit of Two Alien Worlds

'This is something radically different'.
Brad Bergan
An artist's rendition of one of the types of planets orbiting HD 3167.NASA

In the search to find an alien world habitable to human life, astronomers often come across worlds that subvert expectations, but a recent study published in the journal Astronomy & Astrophysics has revealed an entire solar system that's far weirder than first observations suggested.

Two of the planets orbiting the star HD 3167, which is roughly 150 light-years away, are orbiting at a right angle to the plane planets usually follow, going over and under their host star's poles instead of around the equator, like Earth and other planets in our solar system do.

But now researchers have mapped the orbit of the innermost planet, called HD 3167 b, for the first time. And, instead of following the up-down polar orbit like the other two in the system, this one orbits normally, going around its star's equator.

We've never seen anything like this before. And a mysterious, undetected force is wreaking havoc there.

Something enormous has drastically changed a solar system

"It was clearly a surprise," said Vincent Bourrier of the University of Geneva in Switzerland, who led the study, in a report from The New York Times. "This is something radically different from our own solar system." Sadly, it's probable that none of these planets are habitable, but if you could stand on one of them, you would see a bizarre sight. "If you had a telescope and you were looking at the trajectory of the other planets in the system, they would be going vertically in the sky". It's not a complete surprise to find exoplanets locked in polar orbits, said MIT's Andrew Vanderburg, who led the initial discovery of the planets HD 3167 c and d but wasn't a part of the more recent study, in the report. But this solar system's perpendicular distribution "is odd", he added.

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This new finding happened thanks to a specialized instrument equipped on the Very Large Telescope array in Chile, dubbed ESPRESSO. It employed highly precise measurements of the star, enabling scientists to track the direction of motion of the innermost planet as it moved between its host star and us, in an orbital maneuver called a transit. And this examination revealed the angle of the innermost planet's orbit. The system's misalignment may have been caused by an unseen object, and Shweta Dalal of England's University of Exeter said that evidence suggests the possibility of a Jupiter-size planet in orbit of the main star, with a period of 80 days.

An alien solar system is packed extremely tightly

If this is the mysterious force, then its gravitational force may have shoved the outer two planets into unconventional orbits, leaving the innermost planet in place only because the host star, in much greater proximity, held it in place. "A Jupiter-sized planet could be massive enough to tilt the planets," said Dalal, in the NYTimes report. Obviously, our solar system has a Jupiter too, but since planets in our solar system have wider orbits, Earth and the other planets have escaped this baffling perpendicular behavior.

The planets of HD 3167, on the other hand, "are all within the orbit of Mercury," with respect to their host star, said Dalal. Stuffed together in such a tight orbital plane, the gravitational interactions of each planet on the other are extremely magnified. We should count our lucky star (the sun) for being host to a system that was a little less weird, and a little more spacious. Else, we may never have evolved in the first place, and you wouldn't be reading these words.

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