Two billion alien earths in our Galaxy

Recently, after the first results from NASA’s Kepler mission, scientists estimated there could be about 500 miilion Earth-like planets in our Galaxy. According to the new estimate, 1 out of 37 Sun-like stars could harbor an Earth-like world.

Considering the number of Sun-like stars in the Milky Way, billions of Earth-like planets might exist in our Galaxy alone. Scientists at NASA’s Jet Propulsion Laboratory in Pasadena, California, calculated that there could be up to at least 2 billion planets similar to our own.

What is exactly an Earth-like planet? Such a planet is between 0.8 and 2 times the size of Earth, and within the habitable zone of its star (the distance from a star where an Earth-like planet can maintain liquid water on its surface).

With four months of data, the researchers determined that 1.4 to 2.7 percent of the stars similar to our Sun are home to Earth-like planets. Extrapolating to the total amount of Sun-like stars in the Milky Way, that gives 2 billion stars.

It is interesting to note that this only concerns stars similar to the Sun. Red dwarfs, which are much smaller and dimmer could also theoretically support habitable planets. As there are many more of them than Sun-like stars, if they happened to have habitable planets in the same proportions, the number of possible alien earths could skyrocket.

Anyway, even if scientists were to find only one twin planet to ours, that would surely be one of mankind’s greatest discoveries.