On May 10, NASA added 1,284 new planets to its running list of confirmed planets outside of our solar system, or exoplanets. That brings the total well above 3,000.
And those are just the ones we’ve detected. Scientists now believe that, on average, every star in the Milky Way has at least one planet orbiting it.
And there are more than 100 billion stars in our galaxy alone.
With numbers like those, its hard to believe that we’re all alone.
Exploring these exoplanets is our best bet to locate distant neighbors in our lonely chunk of the universe.
Here are some of the most promising places we might find life beyond our solar system:
Scientists judge whether or not a planet is habitable based on factors such as its size, its rockiness and its distance from its host star. The rockier a planet is and the closer it is to the star’s “Goldilock zone” which allows for liquid water, the more likely there is alien life roaming its terrain.
Based on this criteria, exoplanet Kepler-442b was actually found to be even more habitable than Earth. The near Earth-sized planet, discovered in 2015, is about 1,100 light years away. It orbits in the habitable zone of a star slightly cooler than our sun and, if it turns out to be a rocky planet, might only be about twice as massive as Earth.
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Kepler-186f, discovered in 2014, is the first validated Earth-sized planet to be located in the Goldilocks zone of its star. The planet is only 10% larger than Earth and evidence suggests it has a rocky composition. The planet orbits a star about 500 light years away that is cooler and redder than the sun.
Gliese 667 Cc orbits a type of cool, dim star called a red dwarf about 24 light years away. Discovered in 2011, the rocky world sits in the habitable zone of its star. It’s estimated to be have almost four times the mass of Earth but scientists have not yet been able to determine its size.
Alpha Centauri, a three star system just 4 light years away, had its claim to fame recently when Stephen Hawking and Yuri Milner’s initiative “Breakthrough Starshot” announced plans to launch nanocrafts there to search for life. Astronomers believe that there is a reasonable chance of an Earth-like planet existing in one of the star’s Goldilocks zones.
- REUTERS/ESO/L. Calcada/N. Risinger
TRAPPIST-1, an ultracool dwarf star just 40 light years away, made headlines recently when astronomers discovered three Earth-sized planets in its orbit. Although the planets aren’t located in the star’s habitable zones, the fact that two of them are tidally locked, with the same side always facing the sun, might allow the formation of pockets of water, possibly harboring life.
- ESO/M. Kornmesser/N. Risinger/Handout
At the time Kepler-22b was discovered in 2011, it was considered the most Earth-like planet ever discovered. It comfortably circles in the Goldilocks zone of a sun-like star 600 light years away. It is a little more than twice the size of Earth, with an average surface temperature of 72 degrees Fahrenheit.
Kepler-62, a star about 1,200 light years away that is slightly cooler than our sun, is home to not one but two potentially habitable planets. Kepler-62e and Kepler-62f, discovered in 2013, are both super-Earths, meaning they are slightly more massive than our planet. They both fall within the star’s Goldilocks zone.
- REUTERS/NASA Ames/JPL-Caltech/Handout
Kepler-452b, another super-Earth located about 1,400 light years away from us, orbits a star that is 1.5 billion years older than our sun but just as hot. The planet, discovered in 2015, has been in the Goldilocks zone of this star for 6 billion years, leaving plenty of time for life to arise given the right ingredients and conditions.
- REUTERS/NASA/Ames/JPL-Caltech/T. Pyle/Handout