Astronomers have just made an amazing discovery – a rhythmic family of six exoplanets. They are orbiting their host star in the constellation of Leo about 880 light-years from Earth.
The new system, called TOI-178, includes a sizable super-Earth as well as five smaller planets that are closer to the size of Earth’s neighbors Mars and Venus. Researchers believe that at least three of the six planets discovered could be rocky, with possibly two of them hosting liquid water.
With the newfound exoplanet system, the number of multi-planet systems discovered by Kepler, a spacecraft operated by NASA’s Jet Propulsion Laboratory (JPL), has now reached over 500. Furthermore, TOI-178 is now the most compact system of six planets, making it the most crowded world yet found by the Kepler mission.
The uniqueness of TOI-178 comes from the way the planets’ orbits are aligned relative to one another. Deborah Dawson, the primary author of the study on the system, described it as similar to a “clockwork” due to the planets’ rhythmic orbits. Endurance and Zavijava, the two innermost planets, have orbits which are in almost exact resonance with each other. This means that they make regular passes around the star at intervals of two-thirds and one-third of their respective orbits, respectively. Similarly, the more distant planets, Elvira, Tyrone, Plessie, and Zeppo, all orbit in harmonic ratios with their neighbors.
According to Dawson, “This rhythmic behavior is so unique, it’s almost as if this system was meant to be harmonious. Such precise resonances among planets are rare and point towards a surprisingly careful tuning during their formation.”
The discovery of TOI-178 provides important insight into planet formation and exoplanet systems, and may help astronomers more easily classify future similar discoveries. With the number of exoplanet discoveries expected to grow over the coming years, scientists are hopeful that this study will help shed light on the importance of resonance in planetary systems in the future.