A new intergalactic cloud behavior study by researchers from the University of Chicago (UC) and Northwestern University (NU) suggests at least 60 billion planets could sustain water and life, according to a UC press release.
The study examined the role clouds play in planets' climates and, according to the study, the amount of "habitable zone" planets in the Milky Way Galaxy have doubled.
Red dwarfs are the most common stars in the universe and the study suggests nearly 60 billion Earth-sized planets orbit them in what is known as the habitable zone. That zone is an area in a star's orbit where a planet is not too close nor too far from their sun, affecting the climate and whether or not water could exist. The cloud behavior study increases the amount of habitable planets in the galaxy.
"Most of the planets in the Milky Way orbit red dwarfs," said Nicolas Cowan, a postdoctoral fellow at Northwestern's Center for Interdisciplinary Exploration and Research in Astrophysics. "A thermostat that makes such planets more clement means we don't have to look as far to find a habitable planet."
Cowan and UC's Dorian Abbot and Jun Yang combined to co-author the study published in Astrophysical Journal Letters. The authors will also give astronomers the means to test and verify their results with the launch of the James Webb Space Telescope set for 2018.
Before this study, clouds went unaccounted for in habitable zone research. The team recognized in their work that clouds play a large role in a planet's climate.
"Clouds cause warming, and they cause cooling on Earth," said Abbot, an assistant professor in geophysical sciences. "They reflect sunlight to cool things off, and they absorb infrared radiation from the surface to make a greenhouse effect. That's part of what keeps the planet warm enough to sustain life."
Since red dwarfs are smaller and less bright than our sun, the planets around them must complete a much tighter orbit.
"If you're orbiting around a low-mass or dwarf star, you have to orbit about once a month, once every two months to receive the same amount of sunlight that we receive from the sun," Cowan said.
The team used 3D modeling and extensive computer simulations to detect how clouds affected air flow on planets. In fact, their method was similar to how climate is studied on Earth.
"There's no way you can do clouds properly in one dimension," Cowan said. "But in a three-dimensional model, you're actually simulating the way air moves and the way moisture moves through the entire atmosphere of the planet."
