The Milky Way Galaxy Contains About 100 Million Life-Sustaining Planets

The Milky Way Galaxy contains around 100 million places that can support living organisms, according to a report featured in the journal Challenges. The report is the first quantitative estimate of life-harboring planets in our galaxy.

The discovery might make you think that, somewhere in the Milky Way, there is a cantina where alien dregs of all shapes and sizes gather to listen to a repetitive jazz ensemble. Before your mind wanders into imagination land, the study does have some essential caveats.

First, this finding doesn’t necessarily mean the Milky Way has an abundance of complex life. The study focuses on conditions needed for microbial life, simple one-celled organisms like bacteria. Complex life does not mean intelligent life, which would require an even stricter set of environmental requirements (not to mention a lot of luck).

Furthermore, the study does not say that there are organisms on these 100 million worlds. It simply states that the environments on these worlds have the right conditions for simple life forms to live.

Even with all these limitations, this discovery about our Milky Way home is still inspiring.

The report reminds us there is still a lot we don’t know about the Milky Way Galaxy. Another recent discovery may finally give us the size and shape of the Milky Way, something we’ve known about other galaxies for years.

Before, the conditions for life seemed so fastidious that some wondered if it could happen anywhere else at all, much less in our galactic home. There’s density, temperature, planetary chemistry, age of the planet, distance from the nearest star — all factors that can make a planet uninhabitable for life as we know it.

When the researchers who wrote this report compared those factors with 1000 known planets, they found that only 1 to 2 percent could sustain life.

That percentage maybe low, but in a galaxy like the Milky Way, which contains at least 100 billion planets, that 1 to 2 percent means more livable planets than a single person could hope to count in a lifetime.

The study used Europa, a moon circling Jupiter, as the “low bar” for planetary environments (that is to say those 100 million Milky Way worlds can sustain life as well as or better than Europa).

Europa is the only place in the solar system, aside from Earth, where scientists believe there could be life.

It seems strange, Europa isn’t even a planet and it is far from the sun, but Europa contains more water than the Earth. Not only that, the sheer gravity forces from Jupiter push and pull the planet in a way that the center is warm enough for liquid water to exist, although it’s under a thick layer of ice on the surface.

So when will we visit these potentially existent aliens? No time soon.

The closest system that contains one of these life-sustaining planets is Gliese 581, and its about 20 light years away. Our fastest spacecraft, the Voyager 1, would take about 350,000 years to get there.

Until then we’ll have to look out on the Milky Way Galaxy and continue to wonder what might be out there.

(Image Source: Wikipedia)