I'm trying to edit someone's sci-fi novel, and I'm running into a need to refer to levels of gravity in a space station and on other planets in terms of Earth gravity. I cannot find a correct standard for this. Would it be 0.3 g? 0.3 G? 0.3 Gs? 0.3 G's?

And generally it's desirable to spell out units of measure in fiction, I think, but that doesn't really work here, does it? "A third of Earth's gravity" is a fine workaround when it's seldom needed, but when the concept comes up a lot, the correct unit is necessary.

I have had no luck Googling this; believe me, I tried. I'm not even sure if conceptually what I'm dealing with is G (Newton's gravitational constant) or g-force. I have seen both "g" and "G's" used in various places, but what I'm looking for is the accepted standard for use in science fiction novels.

EDIT: For clarity's sake, I should mention that almost all the main characters are humans from Earth or space stations near Earth, so the perspective is based on Earth gravity.

  • The accepted standard for use in science fiction novels written on Telus of Sol or Velantia? Modelled on zero-g, I'd expect 'a 3-g planet', as found in Smith's and Goldin's writings, to be totally acceptable (what would 3-G mean? g is the acceleration due to gravity at the Earth's surface, whereas G is the universal gravitational constant.) But do you really expect SF writers, of all people, to accept literary constraints? Mar 4, 2016 at 22:43
  • @EdwinAshworth So we're looking at, for instance, scenes involving people moving from one place to another on a spinning space station, like, "...passing from Deck A at 0.3 g to Deck Z at a full 'g' would..." I'm totally at a loss.
    – Rae
    Mar 4, 2016 at 22:50
  • Keep in mind that "g" references Earth's gravity. There's no reason to expect residents of the planet Adhoc to use the same term or numbers on the same scale.
    – Hot Licks
    Mar 4, 2016 at 22:51
  • @Hot Licks And chocolate chip cookies (even the best of them) are probably deadly poisonous to Adhocians. Mar 4, 2016 at 22:53
  • 1
    In the d'Alembert series, mention is made of 'three gravities' (meaning the acceleration due to gravity on that world / that deck of the ship is / is set at 30m/s/s). Mar 4, 2016 at 22:57

1 Answer 1


It might require you to embed some explanation up front, but, for levels of gravity in the space station (or other such spacecraft), you could leverage the term micro-g (or µg).

Wikipedia says:

The term micro-g environment is more or less a synonym of weightlessness and zero-g, but indicates that g-forces are not quite zero, just very small.

As for the gravitational forces on other planets, I don't know if there's a "standard" convention, but you could easily devise your own early in the work, and stick with it from there. For example:

Special gravity boots were standard issue on this mission. Xerov was a .3G planet, so Ted would weigh less than one-third of his normal body weight after they landed.

I think most sci-fi fans would be able to put two and two together with an introduction like that.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.