Kepler-22b is a planet orbiting in the habitable zone of its sun-like
star, Kepler-22, which is located roughly 600 light-years from Earth.
With a radius of about 2.4 times that of Earth, astronomers noted after
its discovery in 2011 that the planet's temperatures about the same. If
the greenhouse effect is the same as well, scientists estimated its
surface temperature is a life-friendly 72 degrees Fahrenheit (22 degrees
Celsius).
Although the planet is larger than Earth, astronomers hailed the discovery as a step to Kepler's goal of discovering Earth-size planets in the habitable zones of their respective stars.
"We're getting closer and closer to discovering the so-called 'Goldilocks planet,'" Pete Worden, director of NASA's Ames Research Center in Moffett Field, Calif., said during the 2011 press conference announcing its discovery.
According to NASA's exoplanet archive, Kepler-22b orbits its star every 290 days and is about 0.85 Earth-sun distances or astronomical units away. It has a density that is similar to that of rock, meaning that its environment could be similar to that of Earth -- assuming other properties are also within the same range as our planet.
Habitability depends not only on the distance from the star, but also on things such as the star's variability and whether the planet has an atmosphere. It's harder for current telescopes to pick out planetary properties for those worlds that are closer to Earth's size, however.
Kepler-22b was discovered using the planet-seeking Kepler space telescope, which launched in March 2009 and concluded its primary planetary mission four years later after two of its four reaction wheels or pointing devices failed. (As of late 2013, NASA is considering other uses for the telescope, which could have it looking for planets again.) [Infographic: NASA's Planet-Hunting Kepler Telescope Explained]
The telescope detected thousands of planets, including Kepler-22b, by monitoring a decrease in light from its host star that occurs when the planet passes in front of the star from the perspective of Earth. This process is called the "transit method," as opposed to the "radial velocity" method that looks at how the star wobbles as the planet orbits around it.
Kepler-22b ended up being a very early discovery for the telescope, which caught the planet in the act of transiting only three days after mission managers said the telescope was ready to start observations. The "defining transit", as managers put it, took place during the holidays in 2010.
Although the planet is larger than Earth, astronomers hailed the discovery as a step to Kepler's goal of discovering Earth-size planets in the habitable zones of their respective stars.
"We're getting closer and closer to discovering the so-called 'Goldilocks planet,'" Pete Worden, director of NASA's Ames Research Center in Moffett Field, Calif., said during the 2011 press conference announcing its discovery.
According to NASA's exoplanet archive, Kepler-22b orbits its star every 290 days and is about 0.85 Earth-sun distances or astronomical units away. It has a density that is similar to that of rock, meaning that its environment could be similar to that of Earth -- assuming other properties are also within the same range as our planet.
Habitability depends not only on the distance from the star, but also on things such as the star's variability and whether the planet has an atmosphere. It's harder for current telescopes to pick out planetary properties for those worlds that are closer to Earth's size, however.
Kepler-22b was discovered using the planet-seeking Kepler space telescope, which launched in March 2009 and concluded its primary planetary mission four years later after two of its four reaction wheels or pointing devices failed. (As of late 2013, NASA is considering other uses for the telescope, which could have it looking for planets again.) [Infographic: NASA's Planet-Hunting Kepler Telescope Explained]
The telescope detected thousands of planets, including Kepler-22b, by monitoring a decrease in light from its host star that occurs when the planet passes in front of the star from the perspective of Earth. This process is called the "transit method," as opposed to the "radial velocity" method that looks at how the star wobbles as the planet orbits around it.
Kepler-22b ended up being a very early discovery for the telescope, which caught the planet in the act of transiting only three days after mission managers said the telescope was ready to start observations. The "defining transit", as managers put it, took place during the holidays in 2010.