Two New Habitable Planets Found By NASA Kepler Mission

Eight new Earth-like planets have been found orbiting stars at a distance where water can exist on the surface. Among the eight discovered planets, two of them are believed to most resemble the Earth. These are Kepler-438b and Kepler-442b.

Kepler-438b is located 470 light-years from Earth while the more distant Kepler-442b is 1,100 light-years away. Both stars orbit red dwarf stars which are smaller and cooler than the Sun.

The zone where exoplanets can maintain water in its surface is known as the Goldilocks zone. These planets must receive about as much sunlight as the Earth. The discovery of Kepler-438b and Kepler-442b doubles the number of small planets that are believed to be habitable.

These findings were announced today in a press conference at a meeting of the American Astronomical Society.

Planet Found Orbiting Rare Solar Twin In Open Star Cluster Messier 67

Using ESO's High Accuracy Radial Velocity Planet Searcher (HARPS), astronomers have discovered an exoplanet that is remarkable in two aspects; it is orbiting a rare solar twin and that it is found in an open star cluster.

The planet, found in star cluster Messier 67, is orbiting a star that has features almost identical to the Earth's Sun; a solar twin. This is the first solar twin in a star cluster to have a planet orbiting it. The planet is more massive than Jupiter and takes 122 days to orbit the solar twin.

A star cluster is a group of stars that are bound together by the gravitational attraction of each star. Messier 67 is an open star cluster which is a group of young stars held together by a weak gravitational field. The existence of a planet within a star cluster is considered very rare and that only six have been found out of around 3000 exoplanets discovered (1000 of these exoplanets have been confirmed).

There are two other planets found by HARPS inside Messier 67. One similar to the Sun and the other planet is orbiting a red giant star. The two exoplanets are about 30% the mass of Jupiter.

All three planets are outside the habitable zone and orbit close to their host stars making them too hot which rules out the possibility of the presence of water in them.

20% of Sun-Stars in the Universe Contain Habitable Planets

Astronomers studying data collected by NASA's Kepler spacecraft announced that based on the analysis, one out of every five sun-like stars in the Universe have Earth-sized planets with a surface temperature conducive to life.

Habitable planets are located in an orbit around a star where the heat of the star is just the right temperature where liquid water can exist. Water is one element that is believed to be important to the existence of life. When a planet is too far, water freezes and if it is too close to the star, water vaporizes.

Although it is presumed that the presence of water is an important factor, the planet's atmosphere and surface terrain is also of importance. Without a suitable atmosphere, the planet is exposed to radiation and extreme temperatures. The surface terrain helps harbor the liquid water to sustain life.

By knowing that 20% of sun-like stars harbor a habitable planet, astronomers can start planning for a mission to take an actual picture of it. This also means that there may be habitable planets as close as 12 light years away from the Earth.

The closest exoplanet to the Earth was discovered orbiting Alpha Centauri B in the Alpha Centauri system 4.3 light years away. Although the planet has a mass similar to the Earth, its orbit around Alpha Centauri B is too close to the star that it is outside of the habitable zone.

Two Planets Within Habitable Zone Discovered Orbiting Kepler 62

Researchers have found two planets the size of the Earth within the habitable zone of its star, Kepler 62.

In a short span of years, discoveries of habitable planets have been reported. Observations by the High Accuracy Radial velocity Planet Searcher (HARPS),a high-precision echelle spectrograph, reveal that there may be billions of habitable planets just in the Milky Way alone.

Over 3,000 extrasolar planets (planets located outside the solar system) have been discovered to date. close to 800 of these exoplanets have been identified while the rest are being observed by the Kepler space telescope for confirmation. An exoplanet that is about the same mass of the Earth was observed to be orbiting Alpha Centauri B, the closest star system to the Earth.

Despite the number of planets, scientists are still looking for planets that can be habitable or has features similar to Earth. For it to be habitable, it has to be of the right size, composition, and at a safe distance from its star.