Of all the known planets, Earth is as friendly to life as any planet could be – or is it? If Jupiter’s orbit changes, a new study shows that Earth could be more hospitable than it is today.
When a planet has a perfectly circular orbit around its star, the distance between the star and the planet never changes. However, most planets have “eccentric” orbits around their stars, which means the orbit is elliptical. When a planet approaches its star, it receives more heat, which affects the climate.
Using detailed models based on data from the solar system as it is known today, UC Riverside researchers have created an alternative solar system. In this theoretical system, they found that if the orbit of giant Jupiter became more eccentric, it would in turn lead to significant changes in the shape of the Earth’s orbit.
“If Jupiter’s position remains the same, but the shape of its orbit changes, it could actually increase the habitability of this planet,” said Pam Vervoort, UCR Earth and Planetary Scientist and lead author of the study.
Between zero and 100 degrees Celsius, the Earth’s surface is habitable for many known life forms. If Jupiter pushed the Earth’s orbit to become more eccentric, parts of the Earth would sometimes come close to the Sun. Parts of the Earth’s surface that are now semi-frozen will get warmer, increasing temperatures in the habitable range.
This finding, now published in the Astronomical Journal, overturns two old scientific assumptions about our solar system.
“Many are convinced that Earth is an example of a habitable planet and that any change in the orbit of Jupiter, being the massive planet, could be detrimental to the Earth,” Vervoort said. “We show that both assumptions are wrong.”
The researchers are interested in applying this finding to the search for habitable planets around other stars, called exoplanets.
Said Stephen Kane, an astrophysicist at the University of California, and co-author of the study.
During its orbit, different parts of the planet receive more or less direct rays, which leads to the presence of seasons on the planet. Parts of the planet may be pleasant during one season, and very hot or very cold in another.
“Having water on its surface is a very simple first scale, and it doesn’t take into account the shape of the planet’s orbit, or the seasonal changes that the planet might experience,” Kane said.
Current telescopes are able to measure the planet’s orbit. However, there are additional factors that can affect habitability, such as the degree of inclination of a planet toward or away from the star. The tilted part of the planet further from the star will receive less energy, making it cooler.
This same study found that if Jupiter were placed too close to the sun, it would cause the Earth to tilt so severely that large portions of Earth’s surface would freeze below freezing.
It is difficult to measure the tilt or mass of a planet, so the researchers would like to work on methods that help them estimate these factors as well.
Ultimately, the motion of a giant planet is important in the pursuit of making predictions about the habitability of planets in other systems as well as seeking to understand its impact in this solar system.
“It’s important to understand Jupiter’s influence on Earth’s climate through time, how its influence has changed our orbit in the past, and how it may change us again in the future,” Kane said.
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