This site may earn affiliate commissions from the links on this page. Terms of use.

Artist's impression of the planet orbiting Proxima Centauri

Information technology'south difficult to think now, but there was a long period of time in which scientists weren't certain how many planets might actually exist throughout the galaxy, much less how likely it might be to find a rocky planet. Thank you to missions like Kepler, we now know at that place are likely at to the lowest degree 100 billion planets in our milky way. While many of these aren't capable of supporting life, we now know a solid handful of planets exist that encounter even conservative estimates for where life might survive. We've rounded up some of the near promising examples below.

Before we review the information, we should discuss how exoplanets are typically labeled. Dissimilar television shows like Star Trek, which typically refer to a planet using Roman numerals to represent its position relative to its host star and the host star designation (Cestus III, Ceti Alpha 5), astronomers in the real world employ the alphabet to denote when an exoplanet was discovered effectually its host star. The letter "a" is reserved; planetary designations begin with "b." In the first example we'll exist discussing, the star Kepler-62 is the 62nd star identified by Kepler. The designation Kepler-62f means nosotros're discussing the fifth planet detected in the Kepler-62 organization. Information technology does non necessarily mean that Kepler-62f is the 5th planet in orbit around Kepler-62.

In situations where a star has a common name, this may too exist incorporated into the planet designation. The International Astronomical Marriage gives the example of 51 Pegasi b, which corresponds to the outset planet discovered effectually 51 Pegasi, which is a star in the constellation Pegasus. You can read more than about naming conventions on the IAU's website.

Kepler-62f

Kepler-62f has several qualities that make information technology likely to host life. It orbits a K-type star, which is a type of star similar to the Sunday, but with a longer expected lifetime. Its orbital altitude (0.7 AU), size (ane.41x larger than World) and mass (at least 2.8x college than World) ways that information technology's a rocky planet and could sustain a global ocean.

Kepler-62f

The creative person's concept depicts Kepler-62f, a super-Earth-size planet in the habitable zone of a star smaller and cooler than the sunday, located about 1,200 low-cal-years from Earth in the constellation Lyra. Epitome by NASA

Researchers take identified multiple scenarios that would result in Kepler-62f beingness habitable, depending on the thickness of its atmosphere and the amount of liquid water present on the surface. Information technology's possible that Kepler-62f could be covered in a global ocean, which would dramatically reduce its chances of supporting life. At i,200 light years away, even side by side-generation telescopes won't be able to bank check for the presence of an atmosphere, and SETI has institute no evidence of radio signals, simply its position and characteristics still brand Kepler-62f a leading habitable candidate.

Kepler-186f

Kepler-186f orbits a red dwarf star and is the first planet we've found with a radius like to Earth'south in the habitable zone of its star. Kepler-186f has a radius ~1.11x larger than our own planet. Ane major problem with planets orbiting cherry dwarf stars is that they tend to become tidally locked, with one side of the planet blasted by eternal sunlight while the far side of the planet freezes solid. Theoretically information technology might be possible to live on the terminator of such planets, simply the vast departure in atmospheric temperature would create constant storms every bit air circulated between the hot and cold sides of the planet.

Kepler-186f

This creative person's concept depicts Kepler-186f, the first validated Earth-size planet to orbit a afar star in the habitable zone, a range of distance from a star where liquid water might pool on the planet's surface. Prototype past NASA

But Kepler-186f has a higher orbit than other planets around Kepler-186, making it less probable to exist tidally locked. Scientists judge the planet has a 50 pct adventure of rotating ordinarily. No signals from Kepler-186f have been detected by SETI, though they would have to exist quite powerful to reach the states (10x more powerful than signals from Arecibo) and to have left the home system nearly 500 years ago. To put this in perspective, nosotros've been broadcasting signals other civilizations could've received for less than a century ourselves.

Keppler-442b

Kepler-442b is a super-earth orbiting a Thousand-type star with a radius 1.34x larger than Earth's and a mass estimated at 2.34x of Globe. This would brand surface gravity roughly 30 percent stronger than on our own planet — a significant deviation, but non enough to foreclose alien life from leaving the surface.

Kepler-442b's close position to its host star (0.4x AU, or roughly every bit close to its star as Mercury is to the Sun) doesn't foreclose it as a habitable planet. K-blazon stars are not as luminous as our own and Kepler-442b merely receives nigh 70 per centum of the sunlight the Earth does. The planet is estimated to lie just outside the region where interactions with Kepler-442 would take tidally locked information technology. At i,120 calorie-free years abroad, Kepler-442b is as well besides small and dim to be direct imaged with next-generation telescopes, though the Square Kilometer Array would be able to make much more than detailed observations of the star.

Every bit Kepler continues its mission and telescopes like the James Webb Infinite Telescope come online, our knowledge of stars and their host planets will just increase. Every potentially habitable planet we find fills in our cognition of the cosmos and offers heady opportunities for future research.