NASA has found multiple potentially habitable planets to humans in the universe, but more research is necessary to determine if any of them fit all requirements. The potential planets are all within the habitable zone of the star they revolve around, where the planet is not too far nor too close to their star, so the temperature range is close to that of earth’s. One planet, Kepler-186f, “Confirms that planets the size of Earth exist in the habitable zone of stars other than our sun.” However, Kepler-186f is toward the end of the habitable zone because it only receives 1/3 of the energy from its star as earth gets from the sun.
Perhaps the most crucial element to sustaining lie is water. There are several planets believed to possess liquid water beneath their surfaces, and many more that have water in the form of ice or vapor. Many planets inside and outside the Solar System are believed to have large bodies of water under the surfaces. “Scientists using NASA’s Hubble Space Telescope recently provided powerful evidence that Ganymede has a saltwater, sub-surface ocean, likely sandwiched between two layers of ice.” The four gas giant planets are also believed to have large quantities of water. The presence of alternate forms of water outside earth encourages that there is a habitable planet with similar composition to earth in the universe.