Astronomers discover rare sight: 6 planets orbiting star in 'pristine configuration'

Astronomers gazing upon a star system not too far from Earth were recently treated to a marvelous discovery: a group of six planets moving around a sun-like star in a seemingly perfect cosmic dance routine.

Estimated to be billions of years old, the planetary formation 100 light-years away in the constellation Coma Berenices may help unravel some mysteries of our solar system.

The new planets, revealed in a paper published Wednesday in the journal Nature, could be the key to understanding how planets form and why so many of them are between the size of Earth and Neptune. Little is known about the planetary class, known as "sub-Neptunes," despite how common they are in our Milky Way galaxy, said Rafael Luque, an astronomer at the University of Chicago who led an international team on the study.

“This discovery is going to become a benchmark system to study how sub-Neptunes ... form, evolve, what are they made of,” Luque said in a statement.

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Planets orbiting stars in sync are rare

To make their observations, the team of astronomers turned to a pair of exoplanet-detecting satellites – NASA’s TESS and the European Space Agency’s Cheops.

TESS had detected dips in the brightness of a star known as HD110067 in 2020 that indicated planets were passing in front of its surface. Intrigued, researchers analyzed data from both TESS and Cheops to discover what they said is a first-of-its-kind planetary configuration.

While our galaxy is rife with multi-planet systems, much less common are systems with planets orbiting in a perfect resonance, meaning each planet loops around the host star in a precise, orderly way. In this case, the four planets closest to the star make three orbits for every two of the next planet out, while the two outermost planets make four orbits for every three of the next planet out.

Such synchrony may occur when planets first form, but astronomers theorize that as time goes on, its likely for orbits to get knocked out of rhythm. Close encounters with a passing star, the formation of a massive planet and giant impacts can all upset the gravitational balance of the system.

But the team of astronomers believe that these six planets orbiting the star HD110067 have been miraculously performing this same rhythmic dance since the system formed billions of years ago.

“It shows us the pristine configuration of a planetary system that has survived untouched,” Luque said

Understanding 'sub-Neptune' planets

Other planets in the system could still be undetected, which is why the astronomers are calling for additional observations.

Little is also known about the composition of the planets or their atmospheres, other than that they are gaseous and – because of their proximity to their host star – extremely hot.

It's unlikely the planets located outside the so-called habitable zone support life, but more data may illuminate whether the planets have conditions for liquid water on their surfaces, Luque said.

Further study would also help astronomers solve more mysteries about what sort of chaos ensued to knock the planets in our own solar system out of such harmony.

Eric Lagatta covers breaking and trending news for USA TODAY. Reach him at [email protected]