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article imageOceans crucial as search for alien life gathers pace

By Robert Myles     Jul 21, 2014 in Science
Norwich - New research published Monday on the role of oceans could help determine whether other planets outwith our solar system are capable of developing and sustaining life.
As the number of exoplanets — planets outwith our solar system — discovered rises almost daily, researchers at the UK’s University of East Anglia (UEA) demonstrate the crucial part oceans play in moderating climate on Earth-like planets.
Recent advances in astronomy, such as NASA’s Kepler Space Telescope, have returned a trawl of thousands of candidate planets bearing further scrutiny. Many of these can be eliminated when it comes to supporting alien life, being either too close to their parent star or being gaseous giants like Jupiter, for example.
But within a star system’s circumstellar habitable zone (CHZ), or so-called Goldilocks zone — the region of space in a solar system that’s neither too hot nor too cold — more and more rocky Earth type worlds are being found. As their numbers grow, the focus will turn to what other elements such planets might possess that would contribute to a habitat conducive to the existence of life.
To date, computer models of habitable climates on alien, Earth-like planets have concentrated on the make-up of planetary atmospheres. But in order to sustain life, the UEA researchers say the presence of oceans is vital for optimal climate stability and habitability.
The UEA team based at the university’s schools of Mathematics and Environmental Sciences created a computer simulated pattern of ocean circulation on a hypothetical ocean-covered Earth-like planet. Coupled with that, they examined how different planetary rotation periods (Earth’s being 24 hours) would affect heat transport taking the presence of oceans into account.
Commenting on the research, Professor David Stevens from UEA’s school of Mathematics said, “The number of planets being discovered outside our solar system is rapidly increasing. This research will help answer whether or not these planets could sustain alien life.
“We know that many planets are completely uninhabitable because they are either too close or too far from their sun. 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.”
The professor highlighted oceans as having an immense capacity to control climate. The effect of oceans is largely conducive to the existence of life as the seas cause the surface temperature of a planet to respond very slowly to seasonal changes in solar heating. The oceans act much like a heat sink, or thermostat, ensuring that temperature swings across a planet are kept to tolerable levels.
The researchers found that heat transported by oceans would have a major impact on the temperature distribution planet-wide. At the same time, the existence of oceans would potentially allow a greater area of any one planet to be habitable.
Professor Stevens used Mars as an example to illustrate the important part played by oceans in regulating planetary environments. While the average temperature on Mars is about 218°Kelvin (-55°C), Martian surface temperatures vary widely from as little as 140°K (-133°C) at the winter pole to almost 300°K (27°C) on the day side during summer.
“Mars for example is in the sun’s habitable zone, but it has no oceans — causing air temperatures to swing over a range of 100°C. 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.”
The new model, said Professor Stevens, would contribute to understanding what the climates of other planets might be like with more accurate detail than ever before.
The research, titled, “The Importance of Planetary Rotation Period for Ocean Heat Transport,” is published today, Monday, in the journal Astrobiology.
More about Exoplanets, Exoplanet, Alien life, Kepler space telescope, Kepler spacecraft
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