|Comparison of planets around stars Trappist-1 and some of the planets in our solar system|
(AFP / European Southern Observatory).
For years astronomers have been pursuing the universe to find planets like Earth. Scientists hope to find new planets that could be inhabited by humans, or even find a new alias alien life forms.
This search has found thousands of exoplanets - planets outside our solar system - with a variety of characters, including a number of Earth-like planets are believed to support life.
Included are seven planets orbiting a small star called Trappist-1, which is about 44 light years from Earth. Three of the seven planets is called very similar to Earth, because in addition to a rocky surface is also located in the habitable zone of its parent star.
The discovery of seven planets in the solar system Trappist-1 is reviewed in the journal Nature this week.
But long before the solar system Trappist-1 was discovered, astronomers have known a number of planets with Earth-like characters and even more unique. Here are 7 unique Earth-like planet discovered earlier:
1. Proxima b
Only 4.2 light-years or about 40 trillion kilometers from Earth, dancing a star called Proxima Centauri. He is the star closest parent our solar system, the sun.
European investigators in August 2016 and then announced that there was a planet orbiting Proxima Centauri has a character very much like Earth. Earth's twin is named Proxima b. Its size is about 1.3 times that of Earth.
In addition to a similar size, Proxima b also be in the habitable zone of Proxima Centauri that allegedly could sustain life or even have my own life.
Kepler-438b orbits a red dwarf star within 470 light years from Earth. The planet is considered to be very similar to Earth in terms of radius and weight.
Kepler-438b remains apparently not included that can sustain life, because in a study in 2015 discovered that the planet's parent star is very unstable, is still sending waves of radiation energy that is 10 times more powerful than the energy emitted by our sun.
The planet is located in a binary star system - a system that possessed two parent star. But OGLE-2013-BLG-0341LBb only one star orbiting at a distance equal to the distance of Earth to the sun.
However the parent star OGLE-2013-BLG-0341LBb dimmer than our sun and did not produce enough heat. Therefore the researchers suspect that OGLE-2013-BLG-0341LBb can not be inhabited by humans.
Unique findings of OGLE-2013-BLG-0341LBb the scientists found evidence that rocks berpermukaan planet like Earth, seems to exist in a binary star system.
OGLE-2013-BLG-0341LBb own size about twice the mass of Earth and its discovery was announced in 2013. It is located about 3000 light-years from Earth in the constellation Sagittarius.
The discovery of this planet is a milestone in astronomy because it is the first Earth-like planets are known to be located in the habitable zone. Kepler-186f, whose discovery was announced in 2014, orbiting a red dwarf star located 500 light years from Earth.
Kepler-186f size of about 1.1 times that of Earth. He took the equivalent of 130 Earth days to orbit its parent star - compared with Earth takes about 365 days.
5. Gliese 667 Cc
Gliese 667 Cc distance from Earth only about 24 light-years away. Its mass is about 4 times the mass of Earth, however only about 1.5 times the radius of Earth.
The unique design of Gliese 667 Cc was its location. It is difficult for scientists to trace the planets around Gliese 667 C, the planet's parent star.
In 2016 only two planets that could certainly be in the solar system Gliese 667 C. Allegedly there are five other planets near the star, but there is no accurate data to support this assumption.
6. Wolf 1061c
The planet is larger than Earth, its radius is four times longer than the Earth. In addition, according to the scientists say, he looked more like Uranus than Earth because of the character of its unique atmosphere.
But Wolf 1061c locations are in the habitable zone of its parent star. This planet also had two neighbors who have a rocky surface, the same as two neighboring planet Earth.
The solar system where Wolf 1061c is only 14 light years from Earth.
Announced its discovery in 2011, Kepler-22b measuring 2.4 times that of Earth. He is the first exoplanets were found to lie within the habitable zone.
More unique, Kepler-22b has a parent star similar to our sun. Not only that, one year in duration of Kepler-22b is equivalent to 290 Earth days.
The temperature at the surface of Kepler-22b is estimated that only around 22 degrees Celsius, quite cool as on Earth. Astronomers suspect Kepler-22b's surface covered by oceans.
Yet further research into Kepler-22b could not be held in the near future, because the distance is about 600 light-years from Earth. (Live Science)