A trio of potentially habitable planets has been discovered by the Kepler spacecraft. Each planet is a bit larger than Earth and orbits a star called EPIC 201367065, according to The Institute for Astronomy at the University of Hawaii.
For a planet to be considered "habitable," the temperature must be the Goldilocks standard - "just right" - to support liquid water, which is considered the foundation of life.
"We've learned in the past year that planets the size and temperature of Earth are common in our Milky Way galaxy," University of Hawaii astronomer Andrew Howard said in the press release. "We also discovered some Earth-size planets that appear to be made of the same materials as our Earth, mostly rock and iron."
"There is a very real possibility that the outer planet is rocky like Earth," said a graduate student from the University of California, Berkeley, Erik Petigura, who visited the UH Institute for Astronomy for a year. "If so, this planet could have the right temperature to support liquid water oceans."
The existence of the planets was confirmed by the NASA Infrared Telescope Facility (IRTF) and Keck Observatory in Hawaii, as well as by telescopes in California and Chile. The Hubble Space Telescope will determine atmospheric composition of the three planets.
"A thin atmosphere made of nitrogen and oxygen has allowed life to thrive on Earth," said study lead Ian Crossfield from the University of Arizona. "But nature is full of surprises. Many extrasolar planets discovered by the Kepler mission are enveloped by thick, hydrogen-rich atmospheres that are probably incompatible with life as we know it."
Kepler launched in 2009 but lost two reaction wheels, so it was stuck looking at the same spot. In 2014, it was reborn as K2 when scientists fixed the telescope to point in the plane of the Earth's orbit. "I was devastated when Kepler was crippled by a hardware failure," Petigura said, according to the press release. "It's a testament to the ingenuity of NASA engineers and scientists that Kepler can still do great science."
"It's remarkable that the Kepler telescope is now pointed in the ecliptic, the plane that Earth sweeps out as it orbits the Sun," UH graduate student Benjamin Fulton said. "This means that some of the planets discovered by K2 will have orbits lined up with Earth's, a celestial coincidence that allows Kepler to see the alien planets, and Kepler-like telescopes in those very planetary systems (if there are any) to discover Earth."
So, like the aliens in an episode of "The Simpsons," they could be looking at us, looking at them.
