I'm coming up with a science fiction world for an assignment.

Would it be possible for a planet like Earth to be eaten by a giant alien creature that moves through space at a relatively slow speed and still remain somewhat intact after impact with the back of creatures stomach (assuming the creatures insides is almost like a tunnel). Most research proves that any large impact with Earth would be cataclysmic, I'm just curious that if the speed of which the impact occurs, could it potentially be survivable if the people on this planet had time to build bunkers and technologies that could help them withstand a certain amount of the impact or other destructive results of the incident?

Also would a creature of the size required to eat a planet be able to exist?

It's very far fetched and unbelievable, but I'm just looking for some way of backing it up logically so it's not completely ridiculous. If that's possible.

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    $\begingroup$ If the Earth were eaten, not only would it be covered in eternal darkness, the earth would likely be destroyed by the eating process - if the creature chews. If the creature doesn't chew, and swallows us whole, we're still fcked, because a creature that large would produce a gravitational field that would likely rip the earth apart (and or strip our atmosphere, pull us out of orbit, etc etc) $\endgroup$
    – Aify
    Commented Jun 9, 2015 at 4:45
  • 1
    $\begingroup$ The biggest challenge to large-scale creature design is always the square cube law. $\endgroup$
    – Philipp
    Commented Jun 9, 2015 at 9:28

3 Answers 3


could it potentially be survivable if the people on this planet had time to build bunkers and technologies that could help them withstand a certain amount of the impact or other destructive results of the incident?

I foresee a few problems.

  1. It'll block out sunlight, so the entire food-chain is going to die. People with it.
  2. A giant space alien is going to have lots of mass. Things with mass have gravity. Surrounding a planet is going to have an apparent drop in gravity as suddenly you're going to be pulled 'upwards' towards the alien.
  3. A spinning Earth has a lot of rotational inertia. There's been questions on changing the Earth's spin answered in detail before, and the prognosis is that the Earth is going to continue doing what it wants come hell or high-water. An alien eating us will scour the surface of the Earth flat. No more buildings. No more mountains.

Also would a creature of the size required to eat a planet be able to exist?

Consider the size of such a massive creature and the effect its own gravity would have on itself.

The creature needs to be bigger than Earth, so it's going to be very massive. While it doesn't need to be more massive than Earth, it does need to be hollow. Massive and hollow don't play well together.

This sort of alien needs to be very carefully balanced and incredibly strong otherwise it'll collapse in on itself. The impact of a planet to the inner-surface is more than likely going to upset that balance.

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    $\begingroup$ There would be no change of gravity (assuming the alien has a simmetrical distribution of mass). The parts of the alien over you would attract you upwards, but those on the oppsing side of Earth would attract you downwards (and yes, the areas over you are closer, but the areas under you are greater, both by the square law, so they do cancel) $\endgroup$
    – SJuan76
    Commented Jun 9, 2015 at 8:37
  • $\begingroup$ @SJuan76, that makes sense. Good point. $\endgroup$
    – user6511
    Commented Jun 9, 2015 at 23:10
  • $\begingroup$ I am not sure if I agree with your point 2. If the alien was basically a hollow sphere you would experience an increase in gravity towards the center of that sphere, proportional to your distance to it. If the alien is of a different shape this will become more complicated. However, if you are experiencing a pull away from the earth the earth is experiencing he same pull, meaning that it will not yet be at rest. $\endgroup$
    – Taemyr
    Commented Jul 15, 2015 at 12:07
  • $\begingroup$ Taemyr's comment above is correct, you would be pulled towards the apparent center of mass. But it doesn't matter anyways, because the alien wouldn't suddenly appear surrounding the earth. There'd be a gravitationally awkward transition period as said slow-moving creature approached the Earth and slowly engulfed it. The point where it was close enough to have a significant effect but not yet eating the planet would tear the planet to shreds. $\endgroup$
    – Jason C
    Commented Mar 4, 2017 at 21:11

An early "modern" science fiction story was written by a famous astromomer Fred Hoyle. I recall a series of novels about space vampires bred to combat a threat that was a fine wisp that gathered itself over the planet and ate it. David Gerrold, perhaps? And don't forget one of our planets is missing from Star Trek TAS.

So, there is plenty of precedent for the idea. You ought to read some of those at the very least.

You can probably take latitude with what it means to be eaten. So don't think of a giant star-sized animal, which would be fantasy and not hard SF by today's standards. Get creative. Maybe nanobots are disassembling all the planets, perhaps to create a Matrioshka Brain. Perhaps it is moving in from a different dimension of space where scale is different, and Earth seems small. It might be a grey goo apocalypse of our own making.

For an actual huge creature, an extended cloud or gossamer gause sounds like a good idea, so you avoid the huge mass but it can be very large and what mass you do have can spread out and balance out the gravity.

Contradicting user6511, the source doesn't need to be larger than Earth. It could be a small seed or swarm that converts the planet into more of the same like a virus "eating" a cell, and disperses many many small copies over time.

A survivable scenario at least for individuals in a bunker would be the idea of a wisp gathering around the planet and eating just the thin skin of biosphere. The bulk of the rock would be unaffected, but people often think of the biosphere as "the earth" e.g. how human action is "destroying the planet".


The are many objects in space that are large enough to swallow the earth. Many in our own solar system. Neptune is 3.9 times the earths size but could fit the volume of 57 earths within it. A living planet could definitely consume the earth.


The breakdown of the earth as the surface rotation changed to meet that of the consumer could be part of a digestive system mechanic similar to teeth/chewing(this would also take a long time as the RPMs at the earths surface are so low{.00069 RPM}[or would this depend more upon linear motion? Should it change depending upon how the two objects met?]).

Now what if one of the supper earths hidden within the outer edges of our solar system was an egg for such a creature and it just recently hatched and started moving closer to the more edible sized planets closer to the warmth of the sun Mars, Earth, and Venus? Perhaps it wonders about the Kipper belt first, consuming smaller objects. We might have thousands of years to ready a response. It might even eat our moon first.


Humans could launch themselves into space creating orbital habitats. These could be short term habitats and humans will soon land on the back of the beast. Or long term meant to survive once the beast leaves.

Tunnels could also be built to the center of the earth (science fiction tech level right now).The seismic activities of the first contact would be the largest issue I think. If human built structures survived this then life could continue. Since the current RPM's of the earth would take eons to wear through the crust. Humanity would need an alternative power source to grow food. If nuclear is not good enough, then we can use geothermal as we approach the core.


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