New research suggests planets similar to Earth are much more common across the galaxy than previously thought. “Our solar system is not as unique as we might have thought,” says Courtney Dressing, graduate student at the Harvard-Smithsonian Center for Astrophysics.
Astronomers have discovered eight new exoplanets that may be capable of supporting life as we know it, including what they say are the two most Earthlike alien worlds yet found. One of eight new planets spied in distant solar systems has usurped the title of “most Earth-like alien world”, astronomers have said.
— NASA (@NASA) January 6, 2015
All eight were picked out by Nasa’s Kepler space telescope, taking its tally of such “exoplanets” past 1,000. But only three sit safely within the “habitable zone” of their host star – and one in particular is rocky, like Earth, as well as only slightly warmer.
The Exoplanets orbit red dwarf stars, smaller and less hot than our Sun. Kepler-438b has a 35-Earth-day year: Kepler-442b’s year is 112 days long (the most promising candidates for alien or human habitability). With a diameter just 12 percent bigger than Earth, Kepler-438b has a 70-percent chance of being rocky, according to the team’s calculations. Kepler-442b is about one-third larger than Earth, but still has a 60-percent chance of being rocky.
“We are now closer than we have ever been to finding a twin for the Earth around another star,” Fergal Mullally of the Kepler Science Office said. “These candidates represent the closest analogs to the Earth’s own system found to date.”
Although the two planets may be closest to Earth in size and temperature in the gargantuan scale of the universe, they are not close in distance – being 500 and 1,100 light years away, with a light year measuring 5.9 trillion miles.
“We don’t know for sure whether any of the planets in our sample are truly habitable,” David Kipping of the Harvard-Smithsonian Center for Astrophysics said.
“From the Kepler measurements and the other measurements we made, we don’t know if these planets have oceans with fish and continents with trees,” Doug Caldwell from the Search for Extra-Terrestrial Intelligence Institute in California noted.
“All we know is their size and the energy they’re receiving from their star. So we can say: Well, they’re of a size that they’re likely to be rocky, and the energy they’re getting is comparable to what the Earth is getting,” he continued.
“As we fill in these gaps in our solar system that we don’t have, we learn more about what it means to be Earth-like, in some sense.”
The Harvard-Smithsonian team used a computer program called Blender to confirm that the planets originally spotted by the Kepler space telescope were real (all the planets were too small to confirm by measuring their masses). False sightings can happen when pairs of stars that lie behind the one being studied eclipse each other, causing the background light to dim slightly. In some cases, this can be mistaken for a planet moving in front of its star.
“The pair of stars can be way behind the target star, but if they are in the same line of sight, the result is a very tiny dimming that can look like a planet,” said Torres. The Blender program gives a statistical probability that the planet is real and not an effect of background stars eclipsing one another. Of 12 suspected planets Torres and his colleagues assessed with the program, 11 came out at more than 99.7% likely to be real.