Life-Supporting Planets May Be Rarer Than Previously Thought

The number of planets that could support life in this universe may be far smaller than what experts once thought. According to a new study, planets that orbit red-dwarf stars face extreme space weather, making it less likely that life could survive.

Researchers from the Harvard-Smithsonian Center for Astrophysics (CfA) presented findings that support this claim at the 224th Meeting of the American Astronomy Society on Monday, June 2.

According to a CfA press release that preceded the presentation, lead researcher Ofer Cohen and his team began looking at red dwarf-star solar systems with potentially habitable worlds because these tiny suns make up an estimated 80 percent of the universe's stars.

Unfortunately, close examination of these planets revealed one massive problem concerning their potential to hold life. Because red dwarf stars are smaller and cooler than the Earth's Sun, exoplanets would have to orbit closer to their star to have the same temperature conditions as the Earth - the right conditions to support water and thus life.

However, drawing so close to any star subjects that planet to space weather so strong that it cannot be mitigated by a planet's magnetic field alone.

Looking at the consequences of severe "stellar wind" in particular, the CfA research team used a computer model developed at the University of Michigan to measure the effects being so close to a standard red dwarf star would have on three well-documented planets. They then applied these conditions to life on Earth.

"If Earth were orbiting a red dwarf, then people in Boston would get to see the Northern Lights every night," Cohen said in a statement.

"Oh the other hand, we'd also be in constant darkness because of tidal locking, and blasted by hurricane-force winds because of the dayside-nightside temperature contrast. I don't think even hardy New Englanders want to face that kind of weather," he adds.

The researcher goes on to explain that those weather conditions are actually no laughing matter. Despite the fact that most of these planets would have adequate atmospheric conditions, they would be ravaged by intense winds. "The ultimate consequence is that any planet potentially would have its atmosphere stripped over time."

California-based Search for Extra Terrestrial Intelligence (SETI) experts recently presented thier ongoing projects to the House of Representatives' Science, Space, and Technology Committee, saying that they expect to find life in the next 20 years.

Now, if red-dwarf star systems are to be taken out of the equation, that estimate might have to be revised.