Rogue Planets and the Potential for Life

So Many Lonely Planet With No Star to Guide Them

Our Galaxy may be full of worlds without a sun to call their own.

Scattered about the Milky Way are floating, Jupiter-mass objects, which are likely to be planets wandering around the Galaxy's core instead of orbiting host stars. But these planets aren't rare occurrences in the interstellar sea: the drifters might be nearly twice as numerous as the most common stars...

To find the wanderers, scientists turned their telescopes towards the Galactic Bulge surrounding the centre of the Milky Way. Using a technique called gravitational microlensing, they detected 10 Jupiter-mass planets wandering far from light-giving stars. Then they estimated the total number of such rogue planets, based on detection efficiency, microlensing-event probability and the relative rate of lensing caused by stars or planets. They concluded that there could be as many as 400 billion of these wandering planets, far outnumbering main-sequence stars such as our Sun. Their work is published today in Nature.

Not just outnumbering the number of stars but also the number of planets orbiting them...

They likely outnumber "normal" alien planets with obvious parent stars by at least 50 percent, and they're nearly twice as common in our galaxy as main-sequence stars, according to the new study.

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That number does not just include Jovian-sized worlds but Earth-like as well. Incredibly, despite not having a sun, these interstellar rogues may be capable of harboring life or be life-giving...

Unbound Earth-mass planets might still be capable of carrying liquid water, Stevenson says, even in the frozen reaches of interstellar space – as long as they have a heat-trapping hydrogen atmosphere.

This is supported by another study published earlier this month...

"It has been speculated that Earth-like rogue planets could have very thick atmosphere that keeps them relatively warm, or moons of giant rogue planets could experience tidal heating and have oceans beneath their icy surface," said planetary scientist Heikki Vanhamaki at the Finnish Meteorological Institute in Helsinki.

Source

We live in an extraordinary universe.

reply to post by WingedBull


I think there are two threads on that from last week.

Potential for life on a planet without a stable environment. Probably the least likely to develop life I think.

Its a nice idea but I really don't see how it could be possible for a rogue planet to be habitable , the fact its traveling through space would make it more likely , I would imagine , to bump into stuff like moons or asteroids , maybe even other planets .
I don't see how a planet without a parent star could maintain a temperature suitable to sustain any complex life forms , but I guess if by Potential for Life you mean microbial life forms then yeah , why not , we have found Extremophiles in the harshest places on Earth , I think its safe to assume that given the opportunity life will find a way .

Originally posted by gortex
Its a nice idea but I really don't see how it could be possible for a rogue planet to be habitable , the fact its traveling through space would make it more likely , I would imagine , to bump into stuff like moons or asteroids , maybe even other planets .

In interstellar space, the chances of that happening are far greater than two gnats colliding in the Grand Canyon.

Originally posted by gortex
I don't see how a planet without a parent star could maintain a temperature suitable to sustain any complex life forms...

It would depend on the atmosphere and any tidal forces active on the planet or any orbiting moon.

I think we have a good observational base closer to home in learning more about tidal forces of Neptune and Triton. For a moon to have any chance of exerting tidal forces on a large gas giant in deep space Triton is the best example we have at an observable distance while also considering Triton is a large moon, but only the 7th largest in the solar system. Triton is one of the few moons in the Solar System known to be geologically active. Though by comparison nothing comes close to the mass comparison of our earth and moon, as well as the relative distance but the moon is largely void of tectonic activity.

Yes, there is Pluto and Charon (the closest in size relationship) referred to by some as being a double planetoid, unique in our system as being terrestrial planets beyond the gas giant area of our system, but like Neptune and Triton, are frozen worlds regardless of any tidal activity. I would expect without a star, a rouge planet would need a much larger moon to create sufficient tidal heating, be nearly a double planet system, or have such a mass as to be a near failed star to generate heat in near absolute zero space. I'm not prepared to speculate on what kind of surface if one is defined would be like on a rouge planet that's not frozen, not that a defined surface is necessary for life, but I think a defined surface is necessary for intelligent life capable of a civilization.