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Could Life Survive Without a Star?

Could Life Survive Without a Star?

[♪ INTRO] When we look at life on Earth, we see rich,
diverse ecosystems powered by our host star, the Sun. So, when we think about life elsewhere in the universe, we usually imagine something pretty similar: an Earth-like planet orbiting at an Earth-like
distance from a Sun-like star. But we now know that there are billions of
planets in our galaxy that look nothing like this. In fact, there are billions of rogue planets
that aren’t orbiting a star at all. It’s thought they formed inside star systems
like regular planets, but were then somehow ejected from their original
orbit and flung into deep space. The sheer abundance of these planets has led
some scientists to wonder if life could emerge without a star. And, though obviously we don’t have conclusive
evidence, there’s actually good reason to think it could. It’s hard to imagine anything thriving with
no star because our sun is so vital to life on Earth. But it turns out that a star’s light and
heat might not be deal-breakers. For instance, while the life we’re most
familiar with is powered by sunlight, there are plenty of living things that survive
without it. In fact, for at least a little while, no life
on Earth used sunlight as an energy source. The molecular tools to perform photosynthesis
arose after the first microbes. And that’s part of why multiple hypotheses on how life first emerged involve some pretty dark places. Like, today, we know of a large number of
microorganisms that live deep underground, where they survive off chemical reactions
in the surrounding rocks. So one hypothesis is that life first emerged
in subterranean pockets of water. Or, life could have started around hydrothermal
vents, places on the seafloor where volcanic activity produces jets of steam. A variety of organisms live around these vents, so it’s not hard to imagine life beginning there before it found its way to the surface. What all of these origin stories have in common,
though, is liquid water. That’s because water is vital to all life
on this planet. And if we assume that life, period, needs
liquid water, then its existence on a rogue planet is much less likely, as water can only be liquid at a very narrow
range of temperatures and pressures. Of course, it’s not guaranteed that water
is needed for life. As we said in a previous video on this topic,
“there’s an awful lot of chemistry out there!” But even if life can live without water, it
probably still needs some heat. Deep space is just too cold to envision any
interesting biochemistry going on, water or no water. And without host stars to warm them, most
rogue planets are probably deep-space cold. We’re talking just a few degrees above absolute
zero. Except there are a surprising number of ways
they could be heated up just enough to support life. They might warm themselves from the inside,
for instance. That’s something we see with a lot of planets,
including Earth. In our case, about 10% of the core’s heat
is left over from the collisions that formed Earth, while the rest is from radioactive
decay. And it’s been suggested that similar processes
could produce enough heat inside a rogue planet to warm a subsurface ocean of water for billions
of years, plenty of time for life to emerge and evolve. Even with this kind of core heat, though, a world like this would probably need a surface layer of ice several kilometers thick to act as insulation, much like, oh I don’t know, we see on Jupiter’s
moon Titan. Or, there is another potential way to insulate
a rogue planet: a super-thick atmosphere. A hydrogen-rich one ten to one hundred times
thicker than ours would do the trick. And it turns out rogue planets may be better-suited
to retaining these atmospheres than ones in so-called ‘habitable zones’ around stars, because stellar radiation can blast that sort
of atmosphere away. It’s also possible a rogue planet could get a temperature boost from a mechanism called tidal heating. Essentially, gravity warms up two orbiting
bodies for the same reason it causes tides. The differences in gravity felt by different
parts of the worlds make them squash and stretch, generating large amounts of friction. And again, there seems to be a somewhat local
example a subsurface ocean that’s heated this way: Saturn’s moon Enceladus. So there’s no reason to think that this
couldn’t happen on a rogue planet with its own moon. Now I know what you’re thinking, if these
planets are off roaming the galaxy, they’re probably doing it solo. But it seems like rogue planets can have moons. In fact, simulations suggest that close to
50% of moons could stick by their planets when they go rogue! But before we get too excited about the possibility
of life on these wandering worlds, it’s worth noting that it’s hard to imagine
anything more complex than microorganisms on rogue planets. That’s because these heating mechanisms
give nowhere near as much energy as direct starlight like what we get from our sun. As far as we know, the sun is what gave life
on Earth the ability to evolve the diversity and complexity we see today. Still, it’s fun to imagine what strange
forms of life could be living in pure darkness in a vast, subterranean ocean. Plus, it’s definitely possible that there
are some ambitious creatures out there eeking out a life for themselves on a rogue planet. And who doesn’t want to carve out their
own little piece of the universe? Luckily for us here on Earth, that’s not
quite as tough as it is on a starless world. Like, you can learn more about how to start
and run your own business by watching the Crash Course Business: Entrepreneurship Learning Playlist hosted by Anna Akana. Like SciShow Space, it’s produced by Complexly. And it shows that anyone can be an entrepreneur,
in fact, the first video can help you figure out if you want to be, or already are, one. So whether you’re considering taking your
hobby to the next level or trying to rebuild after a major setback, which is a totally normal part of the process! This 17-episode course can help you figure
out how to take an idea and grow it into a thriving business. If that sounds like something you’d be interested
in, check it out. The link for the playlist in the description. [♪ OUTRO]

100 thoughts on “Could Life Survive Without a Star?”

  1. Ummm… Saturn’s Moon Titan… which ISNT under kilometers of ice (Enceladus is). Europa is Jupiter’s moon with all the ice.

  2. Did Saturn lose a bet with Jupiter? Then how did Jupiter collect Titan? Wow, so much stuff has happened in 2020 already, and it's just January.

  3. What about celestial objects around the heliopause boundary? Wasn't it recently proven that there was a huge temperature increase just outside our solorsystem caused by solar wind smashing into the interstellar medium? Is this stable enough to provide enough heat at one place for a long enough period of time to allow life to form? It appears that at just the right distance from the sun, well past Pluto there's a relatively large area of space near room temperature, no where near just above absolute zero.

  4. Damn… Pretty hard to believe anything this guy says now. Who can say the words "Jupiter's moon, Titan" and pretend to know a single thing about space?

  5. As far as I know we have no quality theory for how life begins. This is an interesting imaginative exercise but ought to be clear how speculative it is.

  6. I thought that when the black hole era kicks in the only way for life to exist would be to collect the Hawking radiation such black holes emit.

  7. Um, Titan is SATURN'S moon, not Juputer's. Did you do this on purpose, just to watch the internet burn? Or do you honestly not know ANYTHING about astronomy, and just read scripts that someone equally as stupid wrote?

  8. I highly doubt it. I highly doubt that life could exist anywhere else, unless there's another solar system out there similar to our own. Another earth-like planet orbiting in the habitable zone of a sun-like star, and the solar system would need at least one gas giant planet orbiting at a distance of about 5.2 AU from its star. We have not found a solar system like that, aside from our own. So our solar system is pretty special, and thank God it is. I like this corner of the universe.

    Great video, keep up the good work. God bless.
    Have a nice day/night.
    ————————————————————————————— with luv from a nerdy Christian.

  9. Could a highly developed species used there whole planet as a spaceship to travel between stars for multiple generations?

  10. Doesn't life already survive without a star near hydrothermal vents in the ocean? GIant tube worms. Though I guess you could argue the sun keeps the oceans from freezing over.

  11. Wait. Ana Akana made more than half of her videos about not knowing what she's doing and now she made a crash course on entrepreneurship? Yeah… No thanks.

  12. Who needs artificial gravity technology when you could borrow a moon from one of the outer planets and use it as a core to build a space ship around. Not so much unlike the death star.

  13. Great vid, but 'in a nutshell' beat ya by a year XD. Love you guys.
    Both content is different enough that i still enjoyed both

  14. At 450 degrees below zero and in darkness the oceans would freeze and all life would cease to exist. Even the hot magma core would start to cool and cool and cool until it turned to rock and even the life on the steam vents would die.The Sun is the source of life consciousness and intelligence. Every cell in my body and thought in my mind is made of Sun. No Sol =No No Soul

  15. Funny that these are basically the circumstances the elves lived in in Tolkien's universe before the sun and moon 🤔🧝‍♂️

  16. I've wondered if hitching a ride on a rogue planet in the distant future would be a good way to travel thru space. You get the planet and resources to live and set up a colony… and eventually you reach a far off solar system or even distant galaxy

  17. Volcanoes, lightning and distant stars could provide some visible light. And if the planet was warmed by the various methods mentioned then the life there could have eyes that see infrared etc. So Darkness wouldn't really be dark. Or they could just use echo location or touch etc to get by.

  18. The host is quite the charmer. And he is a pleasure to listen to. Why didn't I have teachers like that, at school? Oh, well, I had two. But two is not enough and they were not charmers.

  19. There are some theories that liquid CO2 could also be a medium that may allow life to exist. Again it needs to exist in high pressures, but that's the prerequisite for other rogue planets too.

  20. Calling it a rogue "planet" a "wandering world" really suggests that your script writers don't know their science. The word "Planet" is Greek for "Wanderer".

    Actually on second thought, this could be an in-joke that I missed at first. Sorry for the internet-jerk approach (if that's the case).

  21. Possible? Yes. Likely? Not so much. Rogue planets are going to be some of the smaller members of their original systems. That does leave room for them to be Super Earths and smaller Gas Giants. However, planets being whipped around that strongly (like ejecting a Neptune) will likely loose any large moons.
    The moons (Io, Europa, Enceladus) would be more likely to benefit from tidal heating than the larger planet. But ONLY if they are in an highly elliptical orbit. A near double planet (Pluto-Charon) would NOT remain together (more likely to merge into a single body).
    Liquid water isn't the only viable solvent. Ammonia forms the same solutions as water, but really both (plus soluble carbon and trace minerals) and an energy source to support bactiria and fungus. Technology? Not likely at all. No underwater lifeforms have EVER tamed fire or developed radio.

  22. I sometimes wonder if there could be plants that use the light of glowing laa instead of staar light for photosynthesis. If a rogue planet has glowing lava ( maybe from tidal heating from large moons), maybe there could be plants that use the light of it.
    Deepsea ecosystems could exist in rogue planets if they have liquid underground oceans, they would need moons for tidal heating or themselves be the moons of a larger rogue planet.

  23. Going about this another way, there already could be evolved intelligent organisms where oxygen is poison to them, and they die in the heat we are used to and only survive in cold places.

    Even here on earth we have extremophiles.

  24. It's to imagine complex life developing on a rogue planet. Bacteria and other simple life forms would seem more likely.

  25. Imagine if they evolved so completely without light, that instead they can 'see' everything else, but they can't see light…. Radio waves, the electricity flowing through your nerves… Perhaps we're the only ones who have evolved under a sun. Might explain why ufos never have any windows 😂😂😂

  26. If Earth is a perfect place to host life, is new life being generated through chemistry still happening? It happened once, yes, but is it ongoing

  27. The examples that you gave are dubious, the event that ejects the planet could disperse the atmosphere and the moons that you cited are affected by their parent planet and the combined gravity of the Solar System, a different game to just a solitary planet.

  28. Wow there are so many people who are salty about a mistake. They're human too. I know they're trying to inform us, but people in the comments got it. So yeah.

  29. It is possible that many rogue planets are planets that have been kicked out of their natal solar systems ( the systems that they were formed in) due to planet-planet scattering during the formation of their natal solar systems.

  30. "A planet of awesome size, lit by no sun, an invisible titan,
    all thick black forests and jagged mountains and deep, turbulent oceans"

  31. I wonder how often rogue planets get captured by host stars? t would be awesome to think that a planet could get thrown from orbit, develop life in deep space, then travel millions of light-years, and end up at a star producing multicellular life.

  32. One little 'thing'… so far 'we' found approximately ZERO rogue planets. So… how do we know that there are 'billions' of them?

  33. Could Life Start Without a Star is the correct title for this video, Surviving and starting are not the same thing.

  34. A rogue planet with a molten core like ours could also move heat to the atmosphere through volcanism and potentially allow for complex surface life that thrives on those volcanic gasses. I guess it's up to how long these heat sources could continue to operate without a star vs. how long complex life needs to evolve. It's doesn't necessarily need enough time for biogenesis to start; a planet with pre-existing life could use the remaining heat to evolve to better survive the worsening environment. Even if something ejected Earth from our solar system, it's conceivable that humans could survive for a while by burrowing underground.

  35. That photosynthesis wasn't present already in the first life forms (not a hypothesis anyone considers for the first life form, AFAIK) doesn't mean they didn't use sunlight as energy in some other way, even if more indirectly.

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