So basic introduction: my world has things which naturally should never exist due to seemingly violating certain laws we deem as natural, for this, let's just call them "anomalies". Among these various creatures lies one of the most troublesome, simply because it's proportions may most certainly represent a threat.

The creature in question is a space-faring, serpentine-like being that's seemingly made of a singular type of tissue that's borderline indestructible, and sustains itself through strange organs inside of itself which provide both the energy it needs to survive and the propulsion mechanisms it needs to travel through space.

For a more exact description of the thing: It's length is approximately 250000 km, it weights around $6,25 \times 10^{26}$ kg and its cruising speed through the solar system is constant and equal to ~320000 km/h (~89 km/s). In case it's important, the tissues its made of have a density of roughly 100000 $kg/m^{3}$, and its weight is distributed fairly equally throughout its body.

Here's a crude drawing of the being near earth and Jupiter to better illustrate: enter image description here

In the current moment of the story, this being has come closer to our solar system, and, for plot reasons, I wanted it to get as close to earth as possible without outright destroying the planet.

Now, the main problem started to appear when I went to research on the effects of such a thing existing and how it'd interact with nearby celestial bodies (I was having problems picturing the effects of such an astronomical creature in the solar system, and I am no expert in astronomy or the physics involving celestial bodies and planetary masses). I was fairly unsuccessful in understanding how it's own gravity would work, assuming it's mass would still be enough to generate a noticeable gravitational pull despite its shape. I did however find some worrying side effects of its large size and mass while looking for questions with similar themes on this SE, such as that the creature's sheer mass and potential gravity might cause it to shatter the earth's crust simply by getting too close, temporarily mess with the orbits of some planets and even risk causing the moon to be "slingshot" away, unless I got something wrong in what I've read.

So summing it up, because asking about its effects on the solar system would be too broad, what's the closest such a creature could get from Earth before it started to cause serious risks to the planet's integrity? Besides its nigh indestructible body and seeming violation of the laws of thermodynamics, the creature conforms to all known laws of physics.

Answers which also include the effects of it getting too close and whether its long form would cause any major changes to its roche limit, if at all, would be greatly appreciated, as understanding how it's own gravitational forces manifest in its non-spherical body are my main problem right now .

If I've missed any important details or failed to clarify something, please let me know so that I can fix these problems.

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    $\begingroup$ How can this thing be 5 time denser than the densest natural element? $\endgroup$
    – L.Dutch
    Commented Nov 12, 2021 at 3:30
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    $\begingroup$ @L.Dutch -- Administratium $\endgroup$
    – elemtilas
    Commented Nov 12, 2021 at 3:40
  • $\begingroup$ @PcMan Please don't answer in comments. $\endgroup$ Commented Nov 12, 2021 at 8:02
  • $\begingroup$ @PcMan The science-based tag does not require citations, links or math. You're thinking of the hard-science tag $\endgroup$ Commented Nov 12, 2021 at 11:58
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    $\begingroup$ Your creature has close to the same mass as Saturn. It must have an extremely strong internal structure to avoid collapsing into a sphere due to gravity. Imagine tidal effects as it passes close to any planet. $\endgroup$ Commented Nov 12, 2021 at 15:06

2 Answers 2


I used university simulator to simulate what a close encounter between Saturn (which is of a similar mass to earth) would do to earth.

[enter image description here][1

Here is Earth, happy and in a normal orbit.

enter image description here

Here is Earth, in a rather unpleasant orbital distance of 1.45 AU after Saturn flashes near earth and a year passes.

Saturn's Rings are notably wider than Jupiter. The Roche limit of the stellar snake will be at a similar distance. The shape will cause sharper fluctuations.

Having a roaming Saturn would be catastrophic to life on Earth if it got anywhere close, so you might want to reconsider it's speed or gravity if you want it to get close and humans to not all die.

Edit. To calculate the approximate impact of a Saturn near Earth, use this calculator.

Set earth mass as 1, object mass as 95, and I set the distance at 1 sun, about 700000km. The force is approximately 10^27 N. This is about twice as far away as the moon.

Compare this number to this list of energy magnitudes. This is enough force to evaporate most water on earth, and 100,000 times more energy than the energy of the most destructive earthquake in history.

You can adjust the numbers as you choose.

  • $\begingroup$ Just another question: do you know of any resources I could use to better see the effects of this creature should it get very close and calculate its gravity across its body? $\endgroup$ Commented Nov 27, 2021 at 22:42
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    $\begingroup$ I added a method to calculate the impact. $\endgroup$
    – Nepene Nep
    Commented Nov 28, 2021 at 12:27
  • $\begingroup$ @ProjectApex it's roughly the diameter of Earth and 18 times as dense. You can consider it to be a string of about 20 super-earths, each of them being 18 earth masses. Honestly, you may as well just approximate it as a sphere of the same total mass: if it gets close enough for the mass distribution to matter, it makes Earth just as complex by converting it into a debris field. $\endgroup$ Commented Nov 29, 2021 at 0:44
  • $\begingroup$ That simplifies it a lot in figuring out its surface gravity. Thank you very much. $\endgroup$ Commented Nov 29, 2021 at 0:55
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    $\begingroup$ Glad to help. Anything else you want for a best answer? $\endgroup$
    – Nepene Nep
    Commented Nov 29, 2021 at 14:30

Jupiter mass is $1.9 \times 10^{27}$ kg, your creature is half of that.

Considering that Jupiter is already massive enough to perturb Earth's orbit, it's safe to say that that thing should not get anywhere closer than somewhere between the Jupiter orbit and the asteroid belt, even though I am afraid that already its passing through the Oort cloud will cause a massive meteor shower toward the inner solar system, thanks to the jolt it will give to all the bodies orbiting there.

Past that the most likely effects will include disruption of inner solar system orbits, Earth included.

  • $\begingroup$ It's mass is distributed completely differently than a planet. Can you even calculate that? $\endgroup$
    – HyperNym
    Commented Nov 12, 2021 at 5:06
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    $\begingroup$ @HyperNym, until you get much closer, how the mass it's distributed doesn't matter $\endgroup$
    – L.Dutch
    Commented Nov 12, 2021 at 5:08
  • $\begingroup$ And when it gets closer, it's worse - you have half of the mass extending in space closer to you than if it would have been if just a ball. $\endgroup$ Commented Nov 12, 2021 at 6:17
  • $\begingroup$ @HyperNym I think it doesn't matter. It all ends up canceling out. Tidal forces would be massive but I don't think it can physically pull earth apart, so it would be mostly the same as a point mass. $\endgroup$
    – Bubbles
    Commented May 14 at 22:47

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