NASA scientists reached an exciting milestone in the decades-long hunt for planets and possible life outside our solar system Wednesday with the announcement of the discovery of the most Earth-like planet yet.
Quickly dubbed "Earth 2.0" -- the planet, Kepler-452, is a near-Earth-size planet orbiting in what's commonly known as the habitable zone of a star much like our sun. The zone is considered important in the search for life because the temperatures allow for liquid water, which many scientists believe is crucial to fostering life as we know it.
Close cousins? Comparison between Earth and Kepler-452b and their host starsScientists using data from NASA's Kepler...
"On the 20th anniversary year of the discovery that proved other suns host planets, the Kepler exoplanet explorer has discovered a planet and star which most closely resemble the Earth and our Sun," John Grunsfeld, associate administrator of NASA's Science Mission Directorate, said of the discovery. "This exciting result brings us one step closer to finding an Earth 2.0."
As NASA noted in its announcement, the planets have striking similarities.
Both planets orbit a G2-type star of about the same temperature; however, the star hosting Kepler-452b is 6 billion years old, 1.5 billion years older than our sun. As stars age, they become larger, hotter and brighter, as represented in the illustration. Kepler-452b's star appears a bit larger and brighter
Although the planet is far too faint to be seen with the naked eye, stargazers looking to peer in its direction would want to glance toward the constellation Cygnus. The Kepler-452 system where the planet orbits its sun-like star is located 1,400 light-years away.
Scientists named Kepler-452b after the tool they used to find it. The Kepler Space Telescope has been used by the Kepler mission to identify thousands of planets far beyond our solar system.
NASA's Kepler Space Telescope
NASA unveils newly-discovered 'Earth 2.0'
NASA's Kepler spacecraft. (Photo via NASA)
This artist's concept compares Earth (left) to the new planet, called Kepler-452b, which is about 60 percent larger in diameter. (Photo via NASA/JPL-Caltech/T. Pyle)
This artist's concept depicts one possible appearance of the planet Kepler-452b, the first near-Earth-size world to be found in the habitable zone of star that is similar to our sun. The habitable zone is a region around a star where temperatures are right for water -- an essential ingredient for life as we know it -- to pool on the surface. Scientists do not know if Kepler-452b can support life or not. What is known about the planet is that it is about 60 percent larger than Earth, placing it in a class of planets dubbed "super-Earths." 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. Kepler-452b orbits its star every 385 days. The planet's star is about 1,400 light-years away in the constellation Cygnus. It is a G2-type star like our sun, with nearly the same temperature and mass. This star is 6 billion years old, 1.5 billion years older than our sun. As stars age, they grow in size and give out more energy, warming up their planets over time. (Photo via NASA Ames/JPL-Caltech/T. Pyle)
Highlighted are new planet candidates from the seventh Kepler planet candidate catalog that are less than twice the size of Earth and orbit in the stars' habitable zone—the range of distances from a star where liquid water could exist on the surface of an orbiting planet. The dark green area represents an optimistic estimate for the habitable zone, while the light green area represents a more conservative estimate for the habitable zone. The candidates are plotted as a function of the star's surface temperate on the vertical axis and by the amount of energy the planet candidate receives by its host star. Open yellow circles show new planet candidates in the seventh catalog. Open blue circles show candidates from previous catalogs. Filled-in circles represent candidates that have been confirmed as planets due to follow-up observations. Note that the new candidates tend to be around stars more similar to the sun, representing progress in finding planets that are similar to the Earth in size and temperature that orbit sun-like stars. (Photo via NASA Ames/W. Stenzel)
The sweep of NASA Kepler mission’s search for small, habitable planets in the last six years. The first planet smaller than Earth, Kepler-20e, was discovered in December 2011 orbiting a Sun-like star slightly cooler and smaller than our sun every six days. But it is scorching hot and unable to maintain an atmosphere or a liquid water ocean. Kepler-22b was announced in the same month, as the first planet in the habitable zone of a sun-like star, but is more than twice the size of Earth and therefore unlikely to have a solid surface. Kepler-186f was discovered in April 2014 and is the first Earth-size planet found in the habitable zone of a small, cool M dwarf about half the size and mass of our sun. Kepler-452b is the first near-Earth-Size planet in the habitable zone of a star very similar to the sun. (Photo via NASA Ames/W. Stenzel)
This size and scale of the Kepler-452 system compared alongside the Kepler-186 system and the solar system. Kepler-186 is a miniature solar system that would fit entirely inside the orbit of Mercury. The habitable zone of Kepler-186 is very small compared to that of Kepler-452 or the sun because it is a much smaller, cooler star. The size and extent of the habitable zone of Kepler-452 is nearly the same as that of the sun, but is slightly bigger because Kepler-452 is somewhat older, bigger and brighter. The size of the orbit of Kepler-452b is nearly the same as that of the Earth at 1.05 AU. Kepler-452b orbits its star once every 385 days. (Photo via NASA/JPL-CalTech/R. Hurt)
IN SPACE - UNSPECIFIED: In this handout illustration made available on December 5, 2011 by NASA, the Kepler-22b, a planet known to comfortably circle in the habitable zone of a sun-like star is digitally illustrated. For the first time NASA's Kepler mission has confirmed a planet to orbit in a star's habitable zone; the region around a star, where liquid water, a requirement for life on Earth, could persist. The planet is 2.4 times the size of Earth, making it the smallest yet found to orbit in the middle of the habit. Clouds could exist in this earth's atmosphere, as the artist's interpretive illustration depicts. (Photo Illustration by Ames/JPL-Caltech/NASA via Getty Images)
IN SPACE - UNSPECIFIED: In this handout illustration made available on December 5, 2011 by NASA, a diagram compares our own solar system to Kepler-22, a star system containing the first 'habitable zone' planet discovered by NASA's Kepler mission. The habitable zone is the sweet spot around a star where temperatures are right for water to exist in its liquid form. Liquid water is essential for life on Earth. The diagram displays an artist's rendering of the planet comfortably orbiting within the habitable zone, similar to where Earth circles the sun. Kepler-22b has a yearly orbit of 289 days. The planet is the smallest known to orbit in the middle of the habitable zone of a sun-like star and is about 2.4 times the size of Earth. (Photo Illustration by Ames/JPL-Caltech/NASA via Getty Images)
IN SPACE, UNSPECIFIED: In this handout digital illustration released on September 15, 2011 by NASA, the newly-discovered gaseous planet Kepler-16b orbits it's two stars. NASA's Kepler Mission discoverd the world orbiting two Stars, the larger a K dwarf and the smaller a red dwarf. (Photo by NASA/JPL-Caltech/R. Hurt via Getty Images)
IN SPACE, UNSPECIFIED: In this handout digital illustration released on September 15, 2011 by NASA, the newly-discovered gaseous planet Kepler-16b orbits it's two stars. NASA's Kepler Mission discoverd the world orbiting two Stars, the larger a K dwarf and the smaller a red dwarf. (Photo by NASA/JPL-Caltech/T. Pyle via Getty Images)
The graphic tells NASA's Kepler spacecraft's story by the numbers from the moment it began hunting for planets outside our solar system on May 12, 2009. From the trove of data collected, we have learned that planets are common, that most sun-like stars have at least one planet and that nature makes planets with unimaginable diversity. (Photo via NASA Ames/W Stenzel)
(Photo via NASA Ames/W. Stenzel)
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