It is only a matter of time before we will need a new rock to call home.
Fortunately, there are plenty of planets beyond our solar system that are similar in size to Earth and circle stars like our sun.
These planets are known to exist in the “habitable zone,” a region that is not too hot or too cold, but just right to support liquid water, a key ingredient for life as we know it to flourish.
The Planetary Habitability Laboratory, maintained by researchers at the University of Puerto Rico, keeps a list of these Earth-like candidates.
The lab has ranked planets in order of their similarity to Earth, taking size, mass, and distance from their host stars into consideration.
Although we are still working on some kind of vehicle to get to these planets (that would probably require going faster than the speed of light), here are some good destinations to keep in mind for the future — when either we ruin Earth or before an incoming rock from space ruins us.
Kepler-69c belongs to a two-planet system located about 2,700 light-years from Earth.
It's about 70% larger than the size of Earth and orbits its sun-like star every 242 days, which is similar to the orbit of Venus around our sun.
Scientists are not sure what Kepler-69c is made of yet, so travellers should be prepared for anything.
Gliese-581d is one of five planets to be discovered orbiting red dwarf star Gliese 581. It is bigger than 581g, with a mass at least seven times Earth's and twice as big in size.
The planet orbits on the outer edge of the habitable zone and could be warm enough to support clouds, oceans, and rain.
HD 40307 g is one of six planets to orbit around a star called HD 40307, which is 42 light-years away from Earth.
Although the planet is at least seven times the mass of Earth, scientists believe it could have an Earth-like climate because it orbits its parent star at a distance that is similar to that of Earth around our sun.
The planet is far enough away from HD 40307 that it is not tidally locked, meaning it rotates on an axis and does not always show the same face to its star, and each hemisphere has a proper daytime and nighttime.
In September 2012, an international team of astronomers, using the European Southern Observatory's telescope in Chile, discovered Gliese-163c orbiting the star Gliese 163 about 50 light-years from Earth.
Gliese-163c is about seven times the mass of Earth and takes just 26 days to orbit its host star.
The planet is smaller than Kepler-62e at 1.41 times the radius of our planet, making it the most Earth-like planet in size to be found in a habitable zone yet.
Scientists think Kepler-62f could be rocky, based on observations of exoplanets that are similar in size.
Until the discovery of Kepler-62f, Kepler-22b was the smallest planet -- at 2.4 times the radius of Earth -- to orbit a star like our sun within a region where liquid water could exist on the surface.
Although Kepler-22b is 600 light-years away and about twice as big as our own planet, its 290-day orbital period makes the conditions on the planet similar to those on Earth. Its host star is in the same class our sun, but slightly smaller and cooler.
It is not clear if Kepler-22b is gaseous, rocky, or liquid, although an artist's interpretation shows clouds in its atmosphere.
Gliese-667C c, discovered in February 2012, is about 4.5 times the mass of Earth.
The Super-Earth is found 22 light-years away, circling a red dwarf star called Gliese-66C at a distance that is closer than Mercury is to our sun.
It is still possible that Gliese-667C c could have Earth-like temperatures, however -- its parents star is dimmer than our own sun, which reduces the amount of radiation hitting the planet.
Gliese 581g was the first potentially habitable exoplanet discovered by astronomers in September 2010. The distant orb circles a red dwarf star called Gliese 581 that is located about 20 light-years away from Earth.
Gliese 581g, which exists in a five-planet system, is about three times as massive as our planet and is probably rocky, rather than made of gas.
The planet always shows the same face toward its host star as it whips around once every 37 days. This means it is always light in one hemisphere and constantly dark in the other, so that living along the 'light-dark' border would be the most comfortable location to set up house.
The planet is 1.61 times the radius of Earth, although astronomers do not yet know its mass or what it is made of. It could be rocky like Mars or a waterworld. Researchers should be able to discover more about the planet by studying the light that bounces off of it.
To visit our potential new home, space enthusiasts will have to travel 1,200 light-years from Earth, where the planet can be found whirling around a sun-like star called Kepler 62, which is slightly smaller and cooler than our sun.
The latest and best addition to our potential exoplanet homes is Kepler-186f, which is 450 light-years away and is the most Earth-like in size to be found in the habitable zone of its star.
The newly-found planet, described as 'Earth's cousin,' is about 10% larger than Earth and could have liquid water on its surface. That water may be frozen since it orbits the outer edge of the habitable zone. Its host star is also cooler and much smaller than our sun.
Scientists still don't know what Kepler 186f is made of, but think it could have a rocky surface like Earth. Ready to go?
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