exoplanets need oceans to be habitable
July 22, 2014

Oceans Are Important For Life In The Habitable Zone

Brett Smith for redOrbit.com - Your Universe Online

While many previous studies on habitable planetary conditions have focused on the atmosphere, a new study from UK researchers at the University of East Anglia has found that the dynamics of a planet’s ocean is crucial to supporting life.

Published in the journal Astrobiology, the new study shows oceans help to moderate climate on a global scale.

“The number of planets being discovered outside our solar system is rapidly increasing,” said study author David Stevens from UEA’s school of mathematics in a recent statement. “This research will help answer whether or not these planets could sustain alien life.”

“A planet’s habitable zone is based on its distance from the sun and temperatures at which it is possible for the planet to have liquid water,” he added. “But until now, most habitability models have neglected the impact of oceans on climate.”

The study is based on a computer model of ocean circulation on a theoretical ocean-covered planet similar to ours. The team investigated how several planetary rotation rates would affect heat transport with the world’s oceans taken into consideration.

“Oceans have an immense capacity to control climate,” Stevens said. “They are beneficial because they cause the surface temperature to respond very slowly to seasonal changes in solar heating. And they help ensure that temperature swings across a planet are kept to tolerable levels.”

“We found that heat transported by oceans would have a major impact on the temperature distribution across a planet, and would potentially allow a greater area of a planet to be habitable,” he continued.

Stevens pointed out that the planets in our solar system without oceans experience wild swings in temperature that would be extremely hostile to life as we know it.

Mars for example is in the sun’s habitable zone, but it has no oceans – causing air temperatures to swing over a range of (over 200 degrees F),” he said. “Oceans help to make a planet’s climate more stable so factoring them into climate models is vital for knowing whether the planet could develop and sustain life.”

“This new model will help us to understand what the climates of other planets might be like with more accurate detail than ever before,” he added.

Earlier this month, researchers from NASA revealed a computer model which showed how friction may help Earth-sized planets survive destructive orbits. Some computer simulations have shown giant planets of young star systems might disrupt the orbits of smaller planets – pushing them into an unstable orbit. These orbits increase the odds colliding with another planet, being absorbed into the host star or being ejected from the system.

The study researchers found that friction from tidal forces acting on a planet’s liquid interior can act as a corrective measure and guard against a dangerous irregular orbit.

“We found some unexpected good news for planets in vulnerable orbits. It turns out these planets will often experience just enough friction to move them out of harm’s way and into safer, more-circular orbits more quickly than previously predicted,” said study author Wade Henning, a University of Maryland scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.

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