Artist’s concept of a planet where one side always faces its star, with the dark side covered in ice. Credit: Beau.TheConsortium

Alien worlds resembling giant eyeballs might exist around red dwarf stars, and researchers are now proposing experiments to simulate these distant planets and see how capable they are of supporting life.

Red dwarfs are small, faint stars about one-fifth as massive as the Sun and up to 50 times dimmer. They are the most common stars in the galaxy and make up to 70 percent of the stars in the universe, vast numbers that potentially make them valuable places to look for extraterrestrial life. Indeed, the latest results from NASA's Kepler  reveal that at least half of these stars host  that are half to four times the mass of Earth.

When looking for alien life as we know it, scientists typically focus on worlds that have water, since there is life virtually everywhere there is water on Earth. As such, they concentrate on the habitable zone of a star—the area surrounding a star where it is neither too hot nor too cold for liquid water to exist on a planet's surface. Since red dwarfs are so cold, their habitable zones are often closer than the distance Mercury orbits the Sun. This makes it relatively easy for astronomers to spot worlds in a red dwarf's habitable zone—the exoplanets' orbits are small, meaning they complete them quickly and often, and researchers can in principle readily detect the way these worlds regularly dim the light of these stars.

When a planet orbits a star very closely, the  of the star can force the world to become tidally locked with it. "This means that they always show the same side to their star just as our moon does to the Earth, which means they have one permanent day and one permanent night side," study lead author Daniel Angerhausen, an astronomer and  at Rensselaer Polytechnic Institute, Troy, N.Y., told Astrobiology Magazine.

This scenario of permanent day and permanent light could lead to a striking kind of world—one resembling an eyeball. Its night side would be covered in an icy, frozen shell, while its day side would host a giant ocean of liquid water constantly basking in the warmth of its star.

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