Habitable Planets and Exo-Planets

This artist's conception shows the inner four planets of the Gliese 581 system and their host star, a red dwarf star only 20 light years away from Earth.

The large planet in the foreground is the newly discovered GJ 581g, which has a 37-day orbit right in the middle of the star's habitable zone and is only three to four times the mass of Earth, with a diameter 1.2 to 1.4 times that of Earth. Credit: Lynette Cook

The orbits of planets in the Gliese 581 system are compared to those of our own solar system. The Gliese 581 star has about 30 percent the mass of our sun, and the outermost planet is closer to its star than we are to the sun.

The 4th planet, G, is a planet that could sustain life. Credit: Zina Deretsky, National Science Foundation

This image depicts the 3,000 light-year target area for NASA's planet-hunting Kepler spacecraft. Credit: NASA/Jon Lomberg

Astronomers have detected close to 500 distant alien worlds so far — one of which is the right distance from its star to sustain liquid water and possibly even life — and new advances are yielding more planet discoveries faster than researchers can verify them.

These kind of breakthroughs are now revolutionizing what scientists now know of these distant planets, and could in upcoming decades be capable of finding signs of life.