La NASA conferma la scoperta di un vecchio pianeta "cugino" della nostra Terra.
Il pianeta si chiama Kepler 452b e la sua esistenza è stata annunciata oggi dalla Nasa durante una conferenza stampa.
NASA’s Kepler Mission Discovers Bigger, Older Cousin to Earth
This artist's concept compares Earth (left) to the new planet, called Kepler-452b, which is about 60 percent larger in diameter.
Credits: NASA/JPL-Caltech/T. Pyle
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.
Credits: NASA/JPL-CalTech/R. Hurt
There are 4,696 planet candidates now known with
the release of the seventh Kepler planet candidate catalog - an increase
of 521 since the release of the previous catalog in January 2015.
Credits: NASA/W. Stenzel
Since Kepler launched in 2009, twelve planets less
than twice the size of Earth have been discovered in the habitable zones
of their stars.
Credits: NASA/N. Batalha and W. Stenzel
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.
Credits: NASA/JPL-Caltech/T. Pyle
NASA's Kepler mission has confirmed the first near-Earth-size planet
in the “habitable zone” around a sun-like star. This discovery and the
introduction of 11 other new small habitable zone candidate planets mark
another milestone in the journey to finding another “Earth.”
The newly discovered Kepler-452b is the smallest planet to date
discovered orbiting in the habitable zone -- the area around a star
where liquid water could pool on the surface of an orbiting planet -- of
a G2-type star, like our sun. The confirmation of Kepler-452b brings
the total number of confirmed planets to 1,030.
"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," said John
Grunsfeld, associate administrator of NASA’s Science Mission Directorate
at the agency’s headquarters in Washington. “This exciting result
brings us one step closer to finding an Earth 2.0."
Kepler-452b is 60 percent larger in diameter than Earth and is
considered a super-Earth-size planet. While its mass and composition are
not yet determined, previous research suggests that planets the size of
Kepler-452b have a good chance of being rocky.
While Kepler-452b is larger than Earth, its 385-day orbit is only 5
percent longer. The planet is 5 percent farther from its parent star
Kepler-452 than Earth is from the Sun. Kepler-452 is 6 billion years
old, 1.5 billion years older than our sun, has the same temperature, and
is 20 percent brighter and has a diameter 10 percent larger.
“We can think of Kepler-452b as an older,
bigger cousin
to Earth, providing an opportunity to understand and reflect upon
Earth’s evolving environment," said Jon Jenkins, Kepler data analysis
lead at NASA's Ames Research Center in Moffett Field, California, who
led the team that discovered Kepler-452b. "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.”
To help confirm the finding and better determine the properties of
the Kepler-452 system, the team conducted ground-based observations at
the University of Texas at Austin's McDonald Observatory, the Fred
Lawrence Whipple Observatory on Mt. Hopkins, Arizona, and the W. M. Keck
Observatory atop Mauna Kea in Hawaii. These measurements were key for
the researchers to confirm the planetary nature of Kepler-452b, to
refine the size and brightness of its host star and to better pin down
the size of the planet and its orbit.
The Kepler-452 system is located 1,400 light-years away in the
constellation Cygnus. The research paper reporting this finding has been
accepted for publication in The Astronomical Journal.
In addition to confirming Kepler-452b, the Kepler team has increased
the number of new exoplanet candidates by 521 from their analysis of
observations conducted from May 2009 to May 2013, raising the number of
planet candidates detected by the Kepler mission to 4,696. Candidates
require follow-up observations and analysis to verify they are actual
planets.
Twelve of the new planet candidates have diameters between one to two
times that of Earth, and orbit in their star's habitable zone. Of
these, nine orbit stars that are similar to our sun in size and
temperature.
“We've been able to fully automate our process of identifying planet
candidates, which means we can finally assess every transit signal in
the entire Kepler dataset quickly and uniformly,” said Jeff Coughlin,
Kepler scientist at the SETI Institute in Mountain View, California, who
led the analysis of a new candidate catalog. “This gives astronomers a
statistically sound population of planet candidates to accurately
determine the number of small, possibly rocky planets like Earth in our
Milky Way galaxy.”
These findings, presented in the seventh Kepler Candidate Catalog,
will be submitted for publication in the Astrophysical Journal. These
findings are derived from data publically available on the
NASA Exoplanet Archive.
Scientists now are producing the last catalog based on the original
Kepler mission’s four-year data set. The final analysis will be
conducted using sophisticated software that is increasingly sensitive to
the tiny telltale signatures of Earth-size planets.
Ames manages the Kepler and K2 missions for NASA’s Science Mission
Directorate. NASA's Jet Propulsion Laboratory in Pasadena, California,
managed Kepler mission development. Ball Aerospace & Technologies
Corporation operates the flight system with support from the Laboratory
for Atmospheric and Space Physics at the University of Colorado in
Boulder.
For more information about the Kepler mission, visit:
-end-
