Kepler-22b -- Comfortably Circling within the Habitable Zone

Kepler-22b -- Comfortably Circling within the Habitable Zone

This 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.
than our sun, so its habitable zone is slightly closer in. The diagram shows 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. It's about 2.4 times the size of Earth.

Image credit: NASA/Ames/JPL-Caltech
Kepler-22's star is a bit smaller

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Artist's Concept of Kepler-20f

Artist's Concept of Kepler-20f

NASA's Kepler mission has discovered the first Earth-size planets orbiting a sun-like star outside our solar system. The planets, called Kepler-20e and Kepler-20f, are too close to their star to be in the so-called habitable zone where liquid water could exist on a planet's surface, but they are the smallest exoplanets ever confirmed around a star like our sun.

Kepler-20f is the closest object to the Earth in terms of size ever discovered. With an orbital period of 20 days and a surface temperature of 800 degrees Fahrenheit, it is too hot to host life, as we know it.

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

http://www.nasa.gov/kepler

Image credit: NASA/Ames/JPL-Caltech

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Artist's Concept of Kepler-20e

Artist's Concept of Kepler-20e

NASA's Kepler mission has discovered the first Earth-size planets orbiting a sun-like star outside our solar system. The planets, called Kepler-20e and Kepler-20f, are too close to their star to be in the so-called habitable zone where liquid water could exist on a planet's surface, but they are the smallest exoplanets ever confirmed around a star like our sun.

Kepler-20e is the first planet smaller than the Earth discovered to orbit a star other than the sun. A year on Kepler-20e only lasts 6 days, as it is much closer to its host star than the Earth is to the sun. The temperature at the surface of the planet, around 1400 degrees Fahrenheit, is much to hot to support life, as we know it.

Kepler-20e is likely to be entirely rocky and without an atmosphere. The planet is tidally locked, always showing the same side to its host star, as the moon to the Earth, and could have large temperature differences between its permanent night and day sides.

Astronomers think that the planet is likely to be geologically active, due to its own formation process and the strong gravitational interactions with its host star. In this artistic depiction, the planet is represented with active volcanoes on both the night and day sides.

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

http://www.nasa.gov/kepler

Image credit: NASA/Ames/JPL-Caltech

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Earth-class Planets Line Up

Earth-class Planets Line Up

This chart compares the first Earth-size planets found around a sun-like star to planets in our own solar system, Earth and Venus. NASA's Kepler mission discovered the new found planets, called Kepler-20e and Kepler-20f. Kepler-20e is slightly smaller than Venus with a radius .87 times that of Earth. Kepler-20f is a bit larger than Earth at 1.03 times the radius of Earth. Venus is very similar in size to Earth, with a radius of .95 times that our planet. Prior to this discovery, the smallest known planet orbiting a sun-like star was Kepler-10b with a radius of 1.42 that of Earth, which translates to 2.9 times the volume.

Both Kepler-20e and Kepler-20f circle in close to their star, called Kepler-20, with orbital periods of 6.1 and 19.6 days, respectively. Astronomers say the two little planets are rocky like Earth but with scorching temperatures.

There are three other larger, likely gaseous planets also know to circlethe same star, known as Kepler-20b, Kepler-20c and Kepler-20d.

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

http://www.nasa.gov/kepler

Image credit: NASA/Ames/JPL-Caltec

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'Honey I Shrunk the Planetary System'

'Honey I Shrunk the Planetary System'

This artist's conception compares the KOI-961 planetary system to Jupiter and the largest four of its many moons. The KOI-961 planetary system hosts the three smallest planets known to orbit a star beyond our sun (called KOI-961.01, KOI-961.02 and KOI-961.03). The smallest of these planets, KOI-961.03, is about the same size as Mars. All three planets take less than two days to whip around their star.The planets were discovered using data from NASA's Kepler mission and ground-based telescopes. The KOI-961 star is a tiny "red dwarf," just one-sixth the size of our sun. This planetary system is the most compact detected to date, with a scale closer to Jupiter and its moons than another star system.

The planet and moon orbits are drawn to the same scale. The relative sizes of the stars, planets and moons have been increased for visibility.

Image credit: Caltech

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Sizing Up Exoplanets

Sizing Up Exoplanets

This chart compares the smallest known exoplanets, or planets orbiting outside the solar system, to our own planets Mars and Earth. Astronomers using data from NASA's Kepler mission and ground-based telescopes recently discovered the three smallest exoplanets known to circle another star, called KOI-961.01, KOI-961.02 and KOI-961.03. The smallest of these, KOI-961.03, is about the size of Mars with a radius of only 0.57 times that of Earth. Not long ago, in Dec. of 2011, the Kepler team announced the discovery of Kepler-20e and Kepler-20f -- the first Earth-size planets ever found outside the solar system. All five of these small exoplanets have toasty orbits close to their stars, and do not lie in the more temperate habitable zone.

The ground-based observations contributing to the KOI-961 discoveries were made with the Palomar Observatory, near San Diego, Calif., and the W.M. Keck Observatory atop Mauna Kea in Hawaii.Image credit: NASA/JPL-Caltech

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Mini Planetary System

Mini Planetary System

This artist's concept depicts an itsy bitsy planetary system -- so compact, in fact, that it's more like Jupiter and its moons than a star and its planets. Astronomers using data from NASA's Kepler mission and ground-based telescopes recently confirmed that the system, called KOI-961, hosts the three smallest exoplanets known so far to orbit a star other than our sun. An exoplanet is a planet that resides outside of our solar system.

The star, which is located about 130 light-years away in the Cygnus constellation, is what's called a red dwarf. It's one-sixth the size of the sun, or just 70 percent bigger than Jupiter. The star is also cooler than our sun, and gives off more red light than yellow.

The smallest of the three planets, called KOI-961.03, is actually located the farthest from the star, and is pictured in the foreground. This planet is about the same size as Mars, with a radius only 0.57 times that of Earth. The next planet to the upper right is KOI-961.01, which is 0.78 times the radius of Earth. The planet closest to the star is KOI-961.02, with a radius 0.73 times the Earth's.

All three planets whip around the star in less than two days, with the closest planet taking less than half a day. Their close proximity to the star also means they are scorching hot, with temperatures ranging from 350 to 836 degrees Fahrenheit (176 to 447 degrees Celsius). The star's habitable zone, or the region where liquid water could exist, is located far beyond the planets.The ground-based observations contributing to these discoveries were made with the Palomar Observatory, near San Diego, Calif., and the W.M. Keck Observatory atop Mauna Kea in Hawaii.

Image credit: NASA/JPL-Caltech

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