NASA’s Kepler mission announced during a press conference Thursday morning, the discovery of a planet more like Earth than any discovered so far.
According to NASA scientists, Kepler-452b was discovered, through observations of the Kepler space telescope, orbiting in the habitable zone of a G2-type star similar to our Sun, about 1,400 light years away in the Constellation Cygnus.
The discovery of Kepler-452b and its star system was confirmed through independent observations at three sites – the University of Texas at Austin’s McDonald Observatory, the W.M. Keck Observatory at Mauna Kea in Hawaii, and the Fred Lawrence Whipple Observatory of the Smithsonian Astrophysical Observatory near Amado, Arizona.
Kepler-452b is 60 percent larger in diameter than Earth, but it is the smallest planet yet discovered orbiting in the habitable zone of its star, Kepler-452.
The habitable zone of a star, otherwise known as the Goldilocks zone, is the region around the star where temperatures are just right for liquid water and other materials necessary for life to occur on the surface of an orbiting planet.
Kepler-425b’s parent star, called Kepler-452, is about 6 billion years old, that is, 1.5 billion years older than our Sun. It is about 20 percent brighter, with a diameter 10 percent larger, and about the same temperature as the Sun.
Because Kepler-452b is so similar to Earth, scientists estimate a “substantial opportunity” that the planet hosts life similar to Earth. It orbits its star at about the same distance that Earth orbits the Sun and thus has about the same length of year.
The planet is only about 5 percent farther from its parent star than the Earth is from the Sun and has a 385-day orbit, compared with Earth’s 365-day orbital period, equivalent to a sidereal year.
According to John Grunsfeld, NASA’s associate administrator of Science Mission Directorate in Washington, D.C., Kepler-452b is “the closest twin to Earth, or the Earth 2.0 that we’ve found so far in the dataset.”
He added, “This exciting result brings us one step closer to finding an Earth 2.0.”
“The Kepler exoplanet explorer has discovered a planet and star which most closely resemble the Earth and our Sun. This exciting result brings us one step closer to finding an Earth 2.0.”
NASA scientists have not yet determined the new planet’s mass or composition. They are still uncertain whether the planet is rocky. However, they believe it is very likely the planet is rocky.
“While its mass and composition are not yet determined, previous research suggests that planets the size of Kepler-452b have a better than even chance of being rocky.”
Although, scientists have not found evidence of life on Kepler-452b, NASA scientists speculated at the press conference that if plants from Earth were taken to the planet they would be able to photosynthesize and survive because the planet receives about the same spectrum and intensity of light from its star as the Earth receives from the Sun.
According to Dr. Daniel Brown at the Nottingham Trent University, “you could even get a get a healthy tan [on planet Kepler-452b) like here on holiday.”
“This is so fascinating because Kepler 452b receives the same kind of spectrum and intensity of light as we do on Earth. This means plants from our planet could grow there if it were rocky and had an atmosphere.
“You could even get a healthy tan like here on holiday.”
Dr. John Jenkins, who leads the Kepler mission team at NASA’s Ames Research Center in Moffet Field, California, said, “This is the closest thing that we have to another planet like the Earth. It would feel a lot like home based on the sunshine.”
“It’s awe-inspiring to consider that this planet has spent 6 billion years in the habitable zone of its star; longer than Earth. That’s substantial opportunity for life to arise, should all the necessary ingredients and conditions for life exist on this planet.”
The latest discovery brings the total number of planets discovered so far by NASA’s Kepler mission to 1,030. The team was also able to identify more than 520 objects that could be planets, bringing the number of planet candidates discovered by the Kepler mission to more than 4,600.
Scientists point out that having been orbiting its Sun-like star for more than one billion years longer than Earth, the planet would be in a phase of its history that Earth will experience in a billion years from now, thus offering a glimpse of Earth’s future.
According to Dr. Dough Caldwell, with the Kepler mission, the planet could be going through the early stages of runaway greenhouse phase of its climate history, receiving 10 percent more energy from its parent star.
“The increasing energy from its ageing sun might be heating the surface and evaporating any oceans. The water vapor would be lost from the planet forever.”
Kepler-452b takes the distinction of being the most Earth-like planet from Kepler-186F, an Earth-sized planet orbiting the star Kepler-186 about 500 light years from Earth.
The discovery of several Earth-like exoplanets orbiting their stars in the habitable zone, has helped to convince scientists that there must be Earth-like exoplanets with Earth-like biological life. Scientists currently estimate that there are billions of Earth-like exoplanets orbiting their stars in the habitable zone.
NASA scientists hope to be able to refine their search for Earth-like exoplanets when a successor to the Kepler mission is launched in 2017 to scan nearer solar systems for exoplanets.
According to Grunsfeld, scientists equipped with better telescopes will soon be able to determine through direct observation whether newly discovered Earth-like planets have rocky surfaces, oceans, clouds and seasons of the year like Earth’s. They would be able to construct sketchy maps of the planets.
Meanwhile, the Kepler team has submitted a report on its latest finding for publication in the Astrophysical Journal.
[Images: NASA; SETI Institute]