Venus might be habitable today, if not for Jupiter
Study shows destabilizing effect of the giant gas planet

Date:
September 30, 2020
Source:
University of California - Riverside
Summary:
Venus might not be a sweltering, waterless hellscape today, if
Jupiter hadn't altered its orbit around the sun, according to
new research.



FULL STORY ========================================================================== Venus might not be a sweltering, waterless hellscape today, if Jupiter
hadn't altered its orbit around the sun, according to new UC Riverside research.


========================================================================== Jupiter has a mass that is two-and-a-half times that of all other planets
in our solar system -- combined. Because it is comparatively gigantic,
it has the ability to disturb other planets' orbits.

Early in Jupiter's formation as a planet, it moved closer to and then away
from the sun due to interactions with the disc from which planets form
as well as the other giant planets. This movement in turn affected Venus.

Observations of other planetary systems have shown that similar giant
planet migrations soon after formation may be a relatively common
occurrence. These are among the findings of a new study published in
the Planetary Science Journal.

Scientists consider planets lacking liquid water to be incapable of
hosting life as we know it. Though Venus may have lost some water
early on for other reasons, and may have continued to do so anyway,
UCR astrobiologist Stephen Kane said that Jupiter's movement likely
triggered Venus onto a path toward its current, inhospitable state.

"One of the interesting things about the Venus of today is that its
orbit is almost perfectly circular," said Kane, who led the study. "With
this project, I wanted to explore whether the orbit has always been
circular and if not, what are the implications of that?" To answer
these questions, Kane created a model that simulated the solar system, calculating the location of all the planets at any one time and how they
pull one another in different directions.



========================================================================== Scientists measure how noncircular a planet's orbit is between 0, which
is completely circular, and 1, which is not circular at all. The number
between 0 and 1 is called the eccentricity of the orbit. An orbit with
an eccentricity of 1 would not even complete an orbit around a star;
it would simply launch into space, Kane said.

Currently, the orbit of Venus is measured at 0.006, which is the most
circular of any planet in our solar system. However, Kane's model shows
that when Jupiter was likely closer to the sun about a billion years
ago, Venus likely had an eccentricity of 0.3, and there is a much higher probability that it was habitable then.

"As Jupiter migrated, Venus would have gone through dramatic changes in climate, heating up then cooling off and increasingly losing its water
into the atmosphere," Kane said.

Recently, scientists generated much excitement by discovering a gas
in the clouds above Venus that may indicate the presence of life. The
gas, phosphine, is typically produced by microbes, and Kane says it is
possible that the gas represents "the last surviving species on a planet
that went through a dramatic change in its environment." For that to
be the case, however, Kane notes the microbes would have had to sustain
their presence in the sulfuric acid clouds above Venus for roughly a
billion years since Venus last had surface liquid water -- a difficult
to imagine though not impossible scenario.

"There are probably a lot of other processes that could produce the gas
that haven't yet been explored," Kane said.

Ultimately, Kane says it is important to understand what happened to
Venus, a planet that was once likely habitable and now has surface
temperatures of up to 800 degrees Fahrenheit.

"I focus on the differences between Venus and Earth, and what went
wrong for Venus, so we can gain insight into how the Earth is habitable,
and what we can do to shepherd this planet as best we can," Kane said.


========================================================================== Story Source: Materials provided by
University_of_California_-_Riverside. Original written by Jules
Bernstein. Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Stephen R. Kane, Pam Vervoort, Jonathan Horner, Francisco
J. Pozuelos.

Could the Migration of Jupiter Have Accelerated the Atmospheric
Evolution of Venus? The Planetary Science Journal, 2020; 1 (2):
42 DOI: 10.3847/ PSJ/abae63 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/09/200930085157.htm

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