An international team of astronomers have reached the most definitive conclusion, one with profound implications: our galaxy contains a minimum of 100 billion planets. Of those, most are small planets like ours. Statistically, every star would have at least one planet.
According to Stephen Kane — at NASA's Exoplanet Science Institute at CalTech in Pasadena and one of the authors of the study — "not only are planets common in the galaxy, but there are more small planets than large ones. This is encouraging news for investigations into habitable planets."
Kane is being too conservative when he says that this is "encouraging news". This is amazingly great news! The number of Earth-like planets is much higher than Jupiter-sized giants. The rough estimate is that there are at least 10 billion terrestrial planets across our galaxy.
That is a mind-blowing number.
Couple this with the increasing number of planets orbiting in the goldilocks zone — the area where Earth-like environments can happen — and the fact that life happens spontaneously even under the most extreme conditions, and the idea of a Universe thriving with life is impossible to deny. There's no doubt that, statistically, there's life out there.
Of course, how much of this life is smart enough to build computers, communication dishes or Imperial Star Destroyers is another matter altogether. As far as we know, all those habitable worlds may be full of killer snails and dozy fish
But the fact remains that, until now, we could only guess much of this stuff. Now we know. That makes a big difference.
The fact that there are at least 100 billion planets in our Milky Way alone has profound implications for our understanding of the Universe. These discoveries, made using Hubble and Kepler, are finally putting some real numbers in the Drake Equation.
The equation — created by Frank Drake, Emeritus Professor of Astronomy and Astrophysics at the University of California, Santa Cruz — is used to estimate the number of extraterrestrial civilizations in the Milky Way galaxy.
Until know, as Dr Sagan explains in the video above, we could only use educated guesses. Now we are starting to fill in the gaps and things couldn't look better. [Hubble]