June 9 (UPI) -- The presence of airborne dust on alien planets increases the odds of habitability, according to new research. The findings could help planetary scientists hone in on exoplanets most likely to host alien life.
The habitability of a rocky planet depends on its ability to host liquid water. The planet can't be too cold, or water will remain perpetually frozen. If the planet is too hot, all the water will boil away. The type of host star and how far away a planet is from it determines the range of temperatures on the planet's surface.
New planetary models developed by scientists at the University of Exeter, the Met Office and the University of East Anglia showed that the presence of dust can also influence surface temperatures.
Scientists detailed their findings in a new paper, published this week in the journal Nature Communications.
Dust cools the hot side of the planet, the side facing the sun, while warming the dark side of the planet, the side facing away from the sun. In effect, dust expands the planet's habitable zone.
"On Earth and Mars, dust storms have both cooling and warming effects on the surface, with the cooling effect typically winning out. But these 'synchronized orbit' planets are very different," lead study author Ian Boutle, researcher at both Exeter and the Met Office, said in a news release. "Here, the dark sides of these planets are in perpetual night, and the warming effect wins out, whereas on the dayside, the cooling effect wins out."
"The effect is to moderate the temperature extremes, thus making the planet more habitable," Boutle said.
The effect likely has the greatest effect on planets that exist quite close to their host stars.
Planets with intimate orbits often exist right on the inner edge of habitability. The new research suggests some that previously appeared too hot for liquid water, might actually be habitable -- thanks to the cooling effect of airborne dust.
Even seemingly dust-free inner worlds could become friendlier to life over time. As their oceans bubble away, models suggest atmospheric dust concentrations rise, helping to moderate temperatures.
The new research also suggests the presence of dust could complicate efforts to spot biomarkers that might signify the presence of alien life.
For multiple reasons, planetary scientists must now consider the lack or presence of dust when gauging the habitability of distant planets.
"Airborne dust is something that might keep planets habitable, but also obscures our ability to find signs of life on these planets," said study co-author Manoj Joshi, a professor at the University of East Anglia. "These effects need to be considered in future research."