Why some planets orbit backwards?

Experts from Northwestern University in Illinois, USA, conduct a study that was published in the scientific journal Nature, and which required to find the reasons for this phenomenon that breaks with the standard theory of planet configuration. According to this theory, a planet must rotate in the same direction as their star, just like in our solar system. "It's very strange, and it is even rarer because the planet is very close to the star," said Frederic Rasio, an astrophysicist at Northwestern University.

Gravitational perturbation

Scientists developed a model that explains how giant exoplanets known as "hot Jupiters" that orbit very close to their parent star, can change and so retrograde orbit relative to its star. "We believed that our solar system was typical in the universe, but from day one it seemed weird in the extrasolar planetary systems. That now makes our system is the 'oddball' real ' Frederic Rasio, an astrophysicist at Northwestern University.

According to experts, these gas giants usually must orbit in the same direction as their parent star but scientists found that when there are many nearby planets they "disturb" gravitationally. And this leads them to gravitational perturbation of opposite orbit. "Once you have more than one planet gravitationally perturb each other," said Rasio.

"This becomes interesting because it means that the orbit is not necessarily formed in orbit that will stay forever. These mutual perturbations can change the orbits, as we see in these extrasolar systems," he added. According to scientists, in a solar system where several planets, the angular momentum of the planet closest to the star need not be constant and may eventually be retrograde. The model allowed not only explains the peculiar configuration of an extrasolar system, but also contributed to the general understanding of planetary system formation and evolution.

What does the finding for the understanding of the solar system? "We believed that our solar system was typical in the universe, but from day one it seemed weird in the extrasolar planetary systems. That now makes our system the 'freak' of truth," said Rasio. "Learning about these other systems provides a context for how special our system. Certainly seem to live in a special place," he said.