In the Milky Way galaxy alone, 60 billion planets may be orbiting red dwarf stars in the habitable zone, according to
a new study conducted by researchers at the University of Chicago and Northwestern University.
The study, based on computer simulations of cloud behavior on alien planet, dramatically expanded the estimated
habitable zone of red dwarfs, which are much smaller and fainter than stars like the sun.
Current data from NASA's Kepler Mission, a space observatory searching for Earth-like planets orbiting other stars,
suggest there is approximately one Earth-size planet in the habitable zone of each red dwarf.
Artist's concept:a young, red dwarf star surrounded by three planets. Such stars are dimmer
and smaller than yellow stars like our sun. Photo credit: NASA/JPL-Caltech
"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."
The habitable zone refers to the space around a star where orbiting planets can maintain liquid water at their surface.
The formula for calculating that zone has remained much the same for decades. But that approach largely neglects clouds,
which exert a major climatic influence.
"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."
A planet orbiting a star like the sun would have to complete an orbit approximately once a year to be far enough
away to maintain water on its surface.
"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 recent study is very important.
An artist places us on the surface of Gliese 876 d, a planet in or near the habitable zone around a red dwarf star.
Inga Nielsen, Hamburg OBS., Gate To Nowhere
The team's three-dimensional global calculations determined, for the first time, the effect of water clouds on
the inner edge of the habitable zone.
Previous attempts to simulate the inner edge of exoplanet habitable zones were one-dimensional. They mostly
neglected clouds, focusing instead on charting how temperature decreases with altitude.
"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."
These new simulations show that if there is any surface water on the planet, water clouds result. The
simulations further show that cloud behavior has a significant cooling effect on the inner portion of the
habitable zone, enabling planets to sustain water on their surfaces much closer to their sun.
Auroras On Alien Worlds Can Be Stunningly Beautiful
Auroras on Earth are stunning to watch, but have you ever wondered what they might look like on other planets?
We took a journey to some alien worlds to find out what auroras look like there.
There is no doubt that extraterrestrial auroras can be very beautiful on other places in the Universe, and sometimes this light show can be very unique.
Explaining How An Aurora Is Created
Most of us enjoy to watch the beautiful lights in the night sky known as aurora.
These wonderful light display appears primarily over the polar regions. But what exactly causes the aurora?
Radio Emission From Ultracool Dwarf Detected By Arecibo Telescope
The Arecibo Telescope in Puerto Rico has discovered sporadic bursts of polarized radio emission from the T6.5 brown J1047+21.
Because Arecibo is a single, fixed-dish telescope, it has a restricted practical sensitivity to weak, quiescent emission from radio sources...
Invader From Another Galaxy
This alien intruder from another galaxy is in many ways different from other exoplanets observed by astronomers.
Located about 2000 light-years from Earth in the southern constellation of Fornax (the Furnace), the Jupiter-like planet orbits a dying star of
extragalactic origin and risks to be engulfed by it.
Power To See Most Distant Objects In The Universe
The 3C294, is one of the most distant galaxies recorded by Chandra, the most sophisticated X-ray observatory ever built.
The cluster 3C294 is even 40 percent farther (!) than the next most distant x-ray galaxy cluster.
Chandra focus on X-rays from high-energy regions of the Universe and see the invisible.
It is so sensitive that it can capture images of particles as they disappear into a black hole deep in outer space.
"Pillars Of Creation" Are Gone
Every time you look at the beautiful and famous image of the Pillars of Creation taken by Hubble back in 1995,
you are actually admiring something that no longer exists.
In fact, the Pillars of Creation were already long gone by the time the image was captured!