Washington (SINDO) - The Universe is a mystery that is so big. Many people are curious to know the answer to all of the mystery. Similarly, scientists who continue to conduct research on the universe. And because the earth, human habitation, located on the ranks of the Solar System which is actually a part of the universe, the planet was not separated from research.Astronomers describe the number of Earth-like planet is no longer one, as has been revealed. From the results of a recent study, found one out of four stars surrounded by planets similar to Earth. So there are approximately 10 billion planets like Earth in the circumference of the Milky Way.So far, scientists can only predict that the planets were composed of rock. No other information related to the type and amount of content contained on the surface billions of planets.In a simple, provisional estimates it could mean that humans are not alone. So, where it is located? Most of the planet, according to scientists, is in the zone "Goldilocks", this one area of the universe has a temperature that is not too hot or cold to measure water content and the possibility of life.Starting from five years ago, research on planets like Earth was launched. Until now, astronomers have investigated no fewer than 166 sun-like star. Hundreds of stars are scattered in the range of 80 light years (or 470 trillion miles) from Earth.In the last decade, scientists have discovered about 500 planets outside the Solar system. Scientists from the University of California, Berkeley, United States (USA), Dr Andrew Howard had time to reveal the size of planets that have been found. "The two Jupiter-sized planets around six planets of Neptune. While 12 other planets between 3 to 10 times the Earth ". Geoffrey Marcy of the Kepler mission of the U.S. National Space Agency (NASA) participated added, scientists discovered a total of 33 planets orbiting a star 22.