Milky Way may Harbor 100 Million Other Life-Sustaining Worlds

There are some 100 million other places in the Milky Way galaxy that could support complex life, report a group of astronomers in the journal Challenges.

Researchers utilized a newly developed computation method to examine data from planets orbiting other stars in the Universe. While it's possible that other worlds close to home could house living organisms, that's not to say that such planets undeniably exist.

"This study does not indicate that complex life exists on that many planets. We're saying that there are planetary conditions that could support it. Origin of life questions are not addressed - only the conditions to support life," authors said, according to a press release from Cornell University.

The study's team surveyed more than 1,000 planets, looking at factors such as planet density, temperature, chemistry, distance from its central star and age. From there, they created the Biological Complexity Index (BCI) to determine just how many planets in the Milky Way could sustain life.

Calculations revealed that one to two percent of the planets showed a BCI rating higher than Europa, a moon of Jupiter thought to have a subsurface global ocean that may harbor complex forms of life. Out of the roughly 10 billion stars in the Milky Way galaxy, the BCI yields 100 million plausible planets.

"Complex life doesn't mean intelligent life - though it doesn't rule it out or even animal life - but simply that organisms larger and more complex than microbes could exist in a number of different forms," researchers explained.

Despite the large number of possible life-giving planets out there, the Milky Way is vast, with high BCI-valued planets far apart from one another. The closest one to Earth - 20 light years away - is Gliese 581, which has two planets with the apparent, possible capacity to host complex biospheres.

"It seems highly unlikely that we are alone," researchers concluded.