Varying degrees of orbital eccentricity around a central star. (NASA/JPL-Caltech)
As scientists work to understand what might make a distant planet habitable, one factor that is getting attention is the shape of the planet’s orbit, how “eccentric” it might be.
It might seem that a perfect circular orbit would be ideal for habitability because it would provide stability, but a new model suggests that it is not necessarily the case. The planet in question is our own and what the model shows is that if Jupiter’s orbit were to change in certain ways, our planet might become more fertile than it is.
The logic play out as follows:
When a planet has a perfectly circular orbit around its star, the distance between the star and the planet never changes and neither does the in-coming heat. But most planets — including our own — have eccentric orbits around their stars, making the orbits oval-shaped. When the planet gets closer to its star it receives more heat, affecting the climate.
Using multi-factored models based on data from the solar system as it is known today, University of California, Riverside (UCR) researchers created an alternative solar system. In this theoretical system, they found that if Jupiter’s orbit were to become more eccentric, it would in turn produce big changes in the shape of Earth’s orbit. Potentially for the better.
“If Jupiter’s position remained the same but the shape of its orbit changed, it could actually increase this planet’s habitability,” said Pam Vervoort, UCR Earth and planetary scientist and study lead author.
The paper upends two long-held scientific assumptions about our solar system, she said.
“Many are convinced that Earth is the epitome of a habitable planet and that any change in Jupiter’s orbit, being the massive planet it is, could only be bad for Earth,” Vervoort said in a release. “We show that both assumptions are wrong.”
Size comparison of Jupiter and Earth shows why any changes relating to the giant planet would have ripple effects. (NASA)
As she and colleagues report in the Astronomical Journal, if Jupiter pushed Earth’s orbit to become more eccentric based on its new gravitational pull, parts of the Earth would sometimes get closer to the sun. As a results, parts of the Earth’s surface that are now sub-freezing would get warmer, increasing temperatures in the habitable range.
While the Earth-Jupiter connection is a focus of the paper and forms a relationship that’s not hard to understand, the thrust of the paper is modeling how similar kinds of exoplanet orbits and solar system relationships can affect habitability and the potential for life to emerge and prosper.… Read more
