I’m trying to write a new short story that will take place on a craft that is on Neptune (or “in”, depending on how you want to look at it since it’s an ice/gas giant.)

How important is realism to readers? How can I make the story as realistic as possible, based on how Neptune really is?

  • Realism => Wikipedia entry for Neptune
    – BillOnne
    Commented Dec 24, 2022 at 3:01
  • Welcome to Writing.SE! I've removed your second question asking for plot advice, as such questions are off-topic here and questions should only contain one question at a time. The remaining question about realism is perfectly on-topic here.
    – F1Krazy
    Commented Dec 24, 2022 at 12:08
  • I don't think the premise is very realistic, because entering a gas giant sounds like a very expensive way to commit suicide. I'd abandon realism and just go for making it fun.
    – user54131
    Commented Dec 24, 2022 at 19:35
  • @towr: Check out A Meeting with Medusa by Arthur C. Clarke. It is about a mission into the atmosphere of Jupiter.
    – JRE
    Commented Dec 24, 2022 at 22:03

4 Answers 4


You can't get real realism because the technology to visit Neptune doesn't exist (yet.)

What you have to do is to at least not be wrong. I mean, you've specifically picked Neptune. If you don't at least try to get things right then you could have just made up a fantasy place.

Try to get the obvious things right. Neptune is a gas giant, so at least try to consider the difficulties involved in visiting it - getting there, diving into an atmosphere (with horrendous storms) that's very nearly also an ocean, etc.

  • Get things correct that people can easily check or be expected to know. Approximate size, location relative to the other planets, etc.
  • Get basic facts of history correct if your characters refer to them (discovery, discoverer, etc.)
  • At least pay lip service to the difficulties involved in getting there and exploring the place (travel time there, difficulties dealing with the atmospheric pressure, maximum depth the ship can visit, fuel reserves for getting back out again, limited supplies on board, etc.)

People will accept a lot of inaccuracies in a good story, but blatantly wrong things will drive off readers. One story that gets it wrong is Backblast. One part of the plot hinges on an area of space that is especially dangerous because there are so few particles in that region for the rocket engines to push against.

Anything that is mentioned in the narration should be as factual as you can make it - given the limits of common knowledge and fanciful future technology. Common characters (non-specialists) can get things wrong (how many common people can give you a clear description of how a car motor operates,) but characters who should (in-story) know better should not get known facts wrong (a planetologist shouldn't claim that Neptune has an oxygen atmosphere.)

  • It would help to read about hot air balloons (for travel in Neptune's atmosphere) and submarine construction (for how a ship might need to be built to withstand high external pressure.)
  • General knowledge of spaceship operation and travel times would be good (you can't have them travelling from Earth to Neptune in a couple of days unless you at least mention some special ship drive or engine that makes it possible.)

Readers expect to have to suspend their disbelief. Don't break it by putting something blatantly wrong in the story.


Neptune is a gas giant with some of the most extreme weather in the solar system.

It has violent storms that can rage at 2100 km per hour. (Source.)

It has an average temperature of about 214 degrees Celsius. (Source.)

With no solid surface to land on, incredibly low temperatures, and extremely violent storms, sending a craft into Neptune is bound to get it destroyed.

For comparison, the Galileo probe, which was sent into Jupiter, a gas giant of similar make, only lasted about 78 minutes before burning up, losing half its mass, and losing communication with the people who made it. (Source.)

So, to answer your question, how do you write a craft inside of Neptune and make it realistic:

You don't.

A well-made, unmanned probe might last a little while in Neptune's atmosphere, but no one in their right mind would send a craft with people into a gas giant's atmosphere, because that would undoubtedly kill every single person in the crew. Your only way to explain it is by using some ridiculously advanced technology.

I have two suggestions:

  1. Make the story about a craft orbiting around Neptune rather than inside of it. Only people knowledgeable about space will care about what planet the ship is around.

  2. Have the story take place on one of Neptune's moons. With their powerful gravity, gas giants have lots of moons. Some of those moons even have atmospheres of their own.

I suggest the moon Triton as it's the most famous and I believe it has the most atmosphere.

Those are my suggestions. A research station orbiting Neptune or an outpost on one of the moons.

I just can't see any logical reason why a person would send a manned spacecraft straight into Neptune. Any benefit is outweighed by the risk of instant death.


There are more important things: Engaging characters, a well structured plot, crisp and entertaining writing are all more important than realism. Most readers will care more about the realism in characterisation than about realism about (say) visibility at 10000 mBar depth within Neptunes atmosphere.

It is still good to do your research, and to use what we know about the real Neptune in your worldbuilding. It gives your setting depth that is hard to achieve otherwise.

On the other hand, don't let realism get in the way of a good story! The fundamental element of fiction is the suspension of disbelief. Your readers will accept unrealistic things if they follow rules that make sense. You will be creating a fictional Neptune that will be based (more or less) on the real one. Your version of Neptune must convince readers that it could be real, even if elements are made up.


You're not stating in your question if the time/era of this expedition is today (fictional science expedition?), a few years into the future (hard SF?), or far into the future (space opera SF?)

Depending on the time/era of the story your characters might have access to technology that will make this possible.

If it's far future SF, you don't need to explain how the tech works, it's like Clarke said, indistinguishable from magic. Just make sure you don't invent something that makes people indestructible, etc, or you'll remove all danger. (Though the rule is usually that if the protection is magical, so are the weapons and the treats...) And of course, since the descent into Neptune may not be dangerous, you may have to add other dangers instead. (Space monsters?!)

I once did a scene in a far future SF setting where they argued about a past event like this where one side of the argument was along the line "it's innocent fun and you need to live a little" and the counterargument was "you're an idiot and shouldn't be allowed near any gas giants at all".

I suggest you still do research on Neptune. For one to get your facts right and also because the little you've already gotten in other answers here indicates several juicy sources of conflict. Research can bring up the most interesting types of problems and pain you can throw at your characters!

Hyperrealistically, you can, of course, not go to Neptune, not with today's tech, and would you dive into it, it would be a short dive with a violent end.

So I would classify your story as SF regardless of the level of realism you wish to apply.

When it comes to SF, the requirement for realism is usually, even in hard SF, subordinate to not-yet-possible technological advances (though some authors have made predictions that were later realized), the rule of cool (especially cool gadgets, technology, and science), and similar.

For hard SF, you need a technical solution for doing this (perhaps with a pinch of techno-babble handwavium to explain away things we don't yet know how to do today). You could, for instance, get away with protecting your Neptune divers with an energy field even though such a thing could possibly have effects throughout society. That problem is usually solved by making the tech brand new, experimental, and, of course, not entirely reliable. (Only desperate idiots would get into that thing!)

If you don't give a technical explanation, I'm not sure it's hard SF, so the hard SF fans won't be happy, and if it's not in space opera time, neither will the space opera fans.

Although there are, of course, other types of SF as well, not to mention other genres where the story can be "realistic" within its genre such as a comment on Jules Verne's classics along the line of "A (steampunk) Journey into Neptune". Or perhaps a comedy where something hilarious protects them with an even more hilarious result of their dive, or even a children's story where the logic of planet diving need not apply.

The goal isn't usually to be hyperrealistic or even realistic and put that in the novel (it will be super boring), but rather to prevent readers from saying "this is unrealistic rubbish" or constructing a wobbly Ringworld.

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