What would happen if you switched the orbits of Mars and Venus? Would our solar system have more habitable worlds?
It was a question raised at the “Comparative Climatology of Terrestrial Planets III”; a meeting held in Houston at the end of August. It brought together scientists from disciplines that included astronomers, climate science, geophysics and biology to build a picture of what affects the environment on rocky worlds in our solar system and far beyond.
The question regarding Venus and Mars was proposed as a gedankenexperiment or “thought experiment”; a favorite of Albert Einstein to conceptually understand a topic. Dropping such a problem before the interdisciplinary group in Houston was meat before lions: the elements of this question were about to be ripped apart.
The Earth’s orbit is sandwiched between that of Venus and Mars, with Venus orbiting closer to the sun and Mars orbiting further out. While both our neighbors are rocky worlds, neither are top picks for holiday destinations.
Mars has a mass of just one-tenth that of Earth, with a thin atmosphere that is being stripped by the solar wind; a stream of high energy particles that flows from the sun. Without a significant blanket of gases to trap heat, temperatures on the Martian surface average at -80°F (-60°C). Notably, Mars orbits within the boundaries of the classical habitable zone (where an Earth-like planet could maintain surface water) but the tiny planet is not able to regulate its temperature as well as the Earth might in the same location.
Unlike Mars, Venus has nearly the same mass as the Earth. However, the planet is suffocated by a thick atmosphere consisting principally of carbon dioxide. The heat-trapping abilities of these gases soar surface temperatures to above a lead-melting 860°F (460°C).
But what if we could switch the orbits of these planets to put Mars on a warmer path and Venus on a cooler one? Would we find that we were no longer the only habitable world in the solar system?
“Modern Mars at Venus’s orbit would be fairly toasty by Earth standards,” suggests Chris Colose, a climate scientist based at the NASA Goddard Institute for Space Studies and who proposed the topic for discussion.
Dragging the current Mars into Venus’s orbit would increase the amount of sunlight hitting the red planet.… Read more