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Star systems come in all shapes and sizes. Some have many planets, some have larger planets, and some have no planets at all. But a particularly unusual system about 150 light-years from ours has left scientists scratching their heads.

astronomers in 2016 discovered two planets It orbits the star HD 3167. They were thought to be super-Earths between Earth and Neptune in size, and orbit the star every 30 days. A third planet It orbited the system in about eight days in 2017.

Unusual are the tilts of HD 3167 c and d, the two outer planets. While all the planets in our solar system revolve around the sun in the same flat plane, these two are in polar orbits. That is, they go above and below the poles of their star rather than around the equator, as the Earth and other planets in our system do.

Now scientists have discovered that the system is stranger than they thought. This is the first time researchers have measured the orbit of HD 3167 b, the innermost planet, and it doesn’t match the other two. Instead, it orbits in the flat plane of the star and perpendicular to HD 3167 c and d, like the planets in our solar system. This star system is the first known to behave in this way.

“It was clearly a surprise,” said Vincent Bourrier of the University of Geneva in Switzerland, who led the discovery. published last month In the journal Astronomy and Astrophysics. “This is something radically different from our own solar system.”

While none of the planets are considered habitable, if you were to stand on one, you would see a rather intriguing image of this strange system. Dr. “If you had a telescope and were looking at the orbits of other planets in the system, they would be moving vertically across the sky,” Bourrier said.

It’s not entirely unusual to find exoplanets in polar orbits, said Andrew Vanderburg of the Massachusetts Institute of Technology, who led the initial discovery of HD 3167 c and d, but was not involved in the new research. But the vertical nature of this system is “strange,” he said.

The latest discovery was made possible by an instrument called ESPRESSO on the Very Large Telescope in Chile. Using extremely precise measurements of the star, scientists were able to track the direction the innermost planet, known as the transit, passed in front of its star relative to us, and calculate the angle of its orbit.

Misalignment in the system can be caused by an object that is not visible in their external access. Shweta Dalal of the University of Exeter, UK. inspected the system and there is evidence of a Jupiter-sized planet orbiting a star every 80 days, he said. The gravitational effect of this world could have pushed the two outer planets into their unusual orbits, while the innermost planet remained locked to the star due to its tight orbit.

Dr. “A Jupiter-sized planet could be big enough to tilt planets,” Dalal said.

While our solar system may have its own gigantic Jupiter, the wider orbits of our planets mean that the same fate has not befallen Earth or other planets. By contrast, the planets orbiting HD 3167 “are all within the orbit of Mercury,” said Dr. Dalal, and therefore close together, magnifies the effects of their interactions.

Upcoming observations may reveal more systems like this. The European Space Agency’s Gaia telescope, which maps billions of stars in the Milky Way, is expected to soon reveal data on thousands of giant planets in other star systems, including tilt data from transiting ones. Dr. Bourrier and his team hope to use ESPRESSO to make similar observations in other systems.

HD 3167’s unusual configuration highlights just how strange and wonderful other stars and their planets can be. Dr. “It puts into perspective what we think we know about the formation of planetary systems,” Bourrier said. “Planets can really evolve in very different ways.”