In the vast and chaotic environment that is the cosmos, it may be hard to imagine the existence of planets as complex and habitable as Earth. Since NASA’s 2009 Kepler mission, astronomers have risen to the challenge of searching for these Earth-like planets and are finding success.
Earlier this month, a team of astronomers announced the discovery of two “super-Earth” planets residing within a five-planet solar system. San Diego State astronomy professors William Welsh and Jerome Orosz were among the team of 40 researchers who contributed to the finding.
The super-Earth planets, labeled Kepler-62e and Kepler-62f, were found orbiting in a “habitable zone,” which is an area around a star where liquid water can form on a planet and potentially sustain life.
Kepler-62f is approximately 40 percent larger than Earth, and Kepler-62e is about 60 percent larger. They are the smallest planets found in the habitable zone.
“The combination of Earth-sized body and Earth-like temperature is very rare, so these planets are the best cases so far,” Orosz said. “If you want a place to go if you’re getting tired of the Earth, this is our best place to go to.”
Welsh’s research focused primarily on estimating the planets’ temperature to determine if the planets shared the habitable characteristics of Earth.
The discovery was made using data from the Kepler mission. The mission’s purpose is to discover and catalogue potentially habitable planets in the Milky Way. More than 2,700 candidate planets have been found since the mission began.
Orosz explained that in order to locate Earth-like planets, the telescope for the Kepler mission focuses on distant stars and searches for dips in the stars’ light intensity during the course of several years.
“When the planet passes around the star, they make a little dip in the stars’ brightness,” Orosz said. “What Kepler observed in Kepler-62 was a particular star where a very small dip in the brightness seemed to happen on an irregular basis. Our interpretation is that it has five planets that orbit the star on various periods.”
The size and frequency of these dips in light intensity can reveal the size of the planet as well as its distance from the star it orbits. These dips can also be misleading and lead researchers to false conclusions about planetary systems. That is where Orosz’s expertise comes into play.
Orosz said situations called “false positives” can mimic that signal; instead of one star it could be two, but the stars are so far away that they’re blurred together as one.
Part of Orosz’s task was to eliminate ambiguous possibilities.
“The dips in brightness can be diluted, so you can be fooled into thinking that there’s a small planet instead of a big star,” Orosz said.
Welsh and Orosz have helped with the Kepler mission for the last four years. Near the end of 2012, the two also aided in discovering a new type of planet that orbited in the habitable zone in a solar system containing four stars. Their work contributed to the discovery of a dozen new habitable zone planets.
Funding for all research and discoveries was provided by NASA and the National Science Foundation.
