Smallest 'Habitable Zone' Planets to Date

[Waspie_Dwarf]

NASA's Kepler Discovers its Smallest 'Habitable Zone' Planets to Date

Relative sizes of Kepler habitable zone planets discovered as of April 18, 2013. Left to right: Kepler-22b, Kepler-69c, Kepler-62e, Kepler-62f, and Earth (except for Earth, these are artists' renditions). Image credit: NASA Ames/JPL-Caltech.

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MOFFETT FIELD, Calif. -- NASA's Kepler mission has discovered two new planetary systems that include three super-Earth-size planets in the "habitable zone," the range of distance from a star where the surface temperature of an orbiting planet might be suitable for liquid water.

The Kepler-62 system has five planets; 62b, 62c, 62d, 62e and 62f. The Kepler-69 system has two planets; 69b and 69c. Kepler-62e, 62f and 69c are the super-Earth-sized planets.

Two of the newly discovered planets orbit a star smaller and cooler than the sun. Kepler-62f is only 40 percent larger than Earth, making it the exoplanet closest to the size of our planet known in the habitable zone of another star. Kepler-62f is likely to have a rocky composition. Kepler-62e, orbits on the inner edge of the habitable zone and is roughly 60 percent larger than Earth.

The third planet, Kepler-69c, is 70 percent larger than the size of Earth, and orbits in the habitable zone of a star similar to our sun. Astronomers are uncertain about the composition of Kepler-69c, but its orbit of 242 days around a sun-like star resembles that of our neighboring planet Venus.

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Scientists do not know whether life could exist on the newfound planets, but their discovery signals we are another step closer to finding a world similar to Earth around a star like our sun.

"The Kepler spacecraft has certainly turned out to be a rock star of science," said John Grunsfeld, associate administrator of the Science Mission Directorate at NASA Headquarters in Washington. "The discovery of these rocky planets in the habitable zone brings us a bit closer to finding a place like home. It is only a matter of time before we know if the galaxy is home to a multitude of planets like Earth, or if we are a rarity."

The Kepler space telescope, which simultaneously and continuously measures the brightness of more than 150,000 stars, is NASA's first mission capable of detecting Earth-size planets around stars like our sun. Orbiting its star every 122 days, Kepler-62e was the first of these habitable zone planets identified. Kepler-62f, with an orbital period of 267 days, was later found by Eric Agol, associate professor of astronomy at the University of Washington and co-author of a paper on the discoveries published in the journal Science.

The size of Kepler-62f is now measured, but its mass and composition are not. However, based on previous studies of rocky exoplanets similar in size, scientists are able to estimate its mass by association.

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"The detection and confirmation of planets is an enormously collaborative effort of talent and resources, and requires expertise from across the scientific community to produce these tremendous results," said William Borucki, Kepler science principal investigator at NASA's Ames Research Center at Moffett Field, Calif., and lead author of the Kepler-62 system paper in Science. "Kepler has brought a resurgence of astronomical discoveries and we are making excellent progress toward determining if planets like ours are the exception or the rule."

The two habitable zone worlds orbiting Kepler-62 have three companions in orbits closer to their star, two larger than the size of Earth and one about the size of Mars. Kepler-62b, Kepler-62c and Kepler-62d, orbit every five, 12, and 18 days, respectively, making them very hot and inhospitable for life as we know it.

The five planets of the Kepler-62 system orbit a star classified as a K2 dwarf, measuring just two-thirds the size of the sun and only one-fifth as bright. At seven billion years old, the star is somewhat older than the sun. It is about 1,200 light-years from Earth in the constellation Lyra.

A companion to Kepler-69c, known as Kepler-69b, is more than twice the size of Earth and whizzes around its star every 13 days. The Kepler-69 planets' host star belongs to the same class as our sun, called G-type. It is 93 percent the size of the sun and 80 percent as luminous and is located approximately 2,700 light-years from Earth in the constellation Cygnus.

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"We only know of one star that hosts a planet with life, the sun. Finding a planet in the habitable zone around a star like our sun is a significant milestone toward finding truly Earth-like planets," said Thomas Barclay, Kepler scientist at the Bay Area Environmental Research Institute in Sonoma, Calif., and lead author of the Kepler-69 system discovery published in the Astrophysical Journal.

When a planet candidate transits, or passes in front of the star from the spacecraft's vantage point, a percentage of light from the star is blocked. The resulting dip in the brightness of the starlight reveals the transiting planet's size relative to its star. Using the transit method, Kepler has detected 2,740 candidates. Using various analysis techniques, ground telescopes and other space assets, 122 planets have been confirmed.

Early in the mission, the Kepler telescope primarily found large, gaseous giants in very close orbits of their stars. Known as "hot Jupiters," these are easier to detect due to their size and very short orbital periods. Earth would take three years to accomplish the three transits required to be accepted as a planet candidate. As Kepler continues to observe, transit signals of habitable zone planets the size of Earth orbiting stars like the sun will begin to emerge.

Ames is responsible for Kepler's ground system development, mission operations, and science data analysis. NASA's Jet Propulsion Laboratory in Pasadena, Calif., managed Kepler mission development.

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Ball Aerospace & Technologies Corp. in Boulder, Colo., developed the Kepler flight system and supports mission operations with the Laboratory for Atmospheric and Space Physics at the University of Colorado in Boulder.

The Space Telescope Science Institute in Baltimore archives, hosts and distributes Kepler science data. Kepler is NASA's 10th Discovery Mission and was funded by the agency's Science Mission Directorate.

For more information about the Kepler mission and to view the digital press kit, visit:

http://www.nasa.gov/kepler

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Video: Kepler Discovers its Smallest 'Habitable Zone' Planets to Date

Click here to go to a site with downloadable video.

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Text issued as NASA release 13-112 and NASA Ames release 13-31AR

Michele Johnson

Ames Research Center, Moffett Field, Calif.

650-604-6982

michele.johnson@nasa.gov

J.D. Harrington

Headquarters, Washington

202-358-5241

j.d.harrington@nasa.gov

Source

Edited April 18, 2013 by Waspie_Dwarf

[Q-C]

I hope Earth isn't one of a kind.

[Waspie_Dwarf]

I hope Earth isn't one of a kind.

Given the countless possibilities I suspect that Earth will be unique, in the same sort of way that every human on the planet is unique. But given that evidence suggests that there are billions of "Earth like" planets in just this galaxy then there must be countless millions similar enough for life as we know it to have arisen.

[Asadora]

I watched the NASA news briefing (which was on Ustream and NASA TV at 11am PST today) on this latest Kelper discovery and it was pretty awesome, though the reporter from the New Scientist seemed to be sweating a lot when he stood up to ask questions and he wasn't very sure that he understood the answers. Must have been an intern!

Discovery is an awe-inspiring thing and so is watching it live when they announce it.

Yay for Kepler!

Kind Regards

[Geladius]

Bring on the twi'leks

[marcos anthony toledo]

Super Earths Kryptons anyone.

[DBunker]

Given the countless possibilities I suspect that Earth will be unique, in the same sort of way that every human on the planet is unique. But given that evidence suggests that there are billions of "Earth like" planets in just this galaxy then there must be countless millions similar enough for life as we know it to have arisen.

.... with humans???

[Waspie_Dwarf]

.... with humans???

How did you come to that conclusion from what I wrote? I thought what I had written was fairly simple to understand and would require no further explanation. It seems I was wrong.

I mentioned humans as an analogy, to point out that although there are several billion of us and despite are similarities we are all still unique, in the same way that there are believed to be several billion Earth like worlds but none will be exactly like Earth.

I then said that with that many Earth like worlds it is probable that many have life as we know it (actually I used the word "must" which is a bit naughty on my part as I am forever pointing out that "highly probable"and" certain" are not the same thing).

No where did I imply that humans must have arisen on other planets.

[Starseed hybrid 1111]

planet earth is not the only lucky planet to have life however what will be interesting and soon find out is that it might not be in the way most humanity thinks of or some refuse to admit.life exists on many levels and etc people.there are many planets close to earth.

[mrknownothing]

What an amazing time to be alive, hope I'm still here when we prove there is life on other planets.

[Paranomali]

Same here. I hope before I die, it will be common knowledge.