Hellishly Hot Venus Dried Out From the Sun: Planetary Twin Earth Avoids Same Fate

Earth and Venus are more similar than you might think; in fact, they're planetary twins in a sense. They have similar environments and elements, including magma oceans. Yet for some reason, Venus is hellishly hot while Earth supports a variety of life. Now, researchers know why: it's all about location.

During Venus' evolution, ultraviolet rays from the sun sapped the moisture from the planet's atmosphere. This kept it in a prolonged molten state--far longer than Earth's own molten state, according to Space.com. This is probably due to the fact that Venus is far closer to the sun than our own planet by about 25 million miles.

In order to examine the formation of Venus and why it differed so much from Earth, researchers integrated previously separate studies on planet evolution and came up with a simple model that explains why terrestrial bodies like Venus and Earth ended up so different. More specifically, they identified two types of rocky bodies based solely on distance to a parent star. One type, like Venus, stays molten for a prolonged period of time; it was labeled a Type I planet. Another type was similar to Earth and was labeled as Type II.

Type I planets are located far closer to their parent stars. Yet Venus is somewhat unusual in that it straddles the distance between a Type I and Type II planet. Over the years, though, Venus has clearly shown itself to be a Type I planet.

Yet while distance plays an important role, there are other facts that go into whether or not a planet is habitable. A planet must have the right temperature and conditions for surface water and a planet's composition, ability to experience plate tectonics and formation of a protective magnetic field also may be key, according to Discovery News.

"The habitability of Earth and the inhospitability of Venus may be the inevitable result of our planetary sibling order next to the sun rather than later evolutionary bifurcations," wrote planetary scientist Linda Elkins-Tanton in a paper published in this week's Nature. "If so, similar patterns of habitability are likely to be found in exoplanets."

The findings could be essential for understanding how planets could support life. In addition, they could allow researchers to better search for life on alien planets in the future.