Planetary systems can have up to 7 planets in the habitable zone

Hyperaxion Aug 1, 2020

The Solar System has no other Earth-like planets because of Jupiter’s interference, according to new research.

A new study by the University of California, Riverside, in the United States, indicates that the existence of habitable exoplanets in the Universe may be more common than previously thought.

Planetary systems can have up to 7 planets in the habitable zone
The Trappist-1 System compared to ours. (Credit: NASA / JPL-Caltech).

According to the research, published earlier this week in The Astronomical Journal, other planetary systems could house up to seven Earth-like planets.

To look for evidence of life as we know it, scientists focus on the so-called “habitable zone”, the area around a star in which a planet can have liquid water.

The study’s leader Stephen Kane decided to conduct the research after analyzing a nearby solar system called Trappist-1, which has three Earth-like planets in its habitable zone.

“This made me wonder about the maximum number of habitable planets it’s possible for a star to have, and why our star only has one,” Kane said. “It didn’t seem fair!”

His team created a model to simulate planets of various sizes orbiting their stars. An algorithm was created to add the gravitational forces and the interaction of all objects in the system over millions of years.

This is how, according to Kane, the team found that some stars can support up to seven planets in the habitable zone – in the case of stars like the Sun, that number drops to six. “More than seven, and the planets become too close to each other and destabilize each other’s orbits,” Kane explained.

So, why doesn’t the Solar System have other planets in the habitable zone?

First, the shape of the orbits plays a role: circular orbits facilitate this, while elliptical orbits (such as the orbit of the Earth and its neighbors) make it difficult.

However, scientists believe that the main responsible for the absence of other planets in the habitable zone of the Solar System is Jupiter.

The gas giant has a mass equivalent to two and a half times that of all other planets in the system combined.

“It has a big effect on the habitability of our solar system because it’s massive and disturbs other orbits,” Kane said.

In the future, the team plans to create models that take into account the atmospheric chemistry of planets in the habitable zones of other planetary systems.

“Although we know Earth has been habitable for most of its history, many questions remain regarding how these favorable conditions evolved with time, and the specific drivers behind those changes,” Kane said. “By measuring the properties of exoplanets whose evolutionary pathways may be similar to our own, we gain a preview into the past and future of this planet — and what we must do to main its habitability.”


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