I stumbled upon this sentence in Wikipedia:

Titan is 50% larger than Earth's moon and 80% more massive.

I struggle with the "more massive" part. I find some books do use that phrase. Is it correct, pedantically? Do you recommend using it? Do you use it oftentimes, especially if you are an astronomer?

Which one do you prefer: "more massive" or "more in mass" or just "heavier"? Any other alternative is welcome.

  • Massive solid planet is an expression used in astronomy: Massive solid planets. Solid planets up to thousands of Earth masses may be able to form around massive stars (B-type and O-type stars; 5–120 solar masses), where the protoplanetary disk would contain enough heavy elements. en.m.wikipedia.org/wiki/Giant_planet#Massive_solid_planets
    – user 66974
    May 18, 2020 at 7:28
  • 4
    "Heavier" would be a reference to weight rather than mass, and while I'm not an astronomer I don't think it makes sense to talk about a planet or moon's weight.
    – nnnnnn
    May 18, 2020 at 7:52
  • 1
    Although '50% more voluminous' is not idiomatic, '50% more massive' (with, of course, the meaning 'having a mass 1·5 times that of the antecedent') is. The confusion arises because of the conflicting everyday and scientific definitions / distributions of 'mass' / 'massive'. May 18, 2020 at 11:36
  • How about 80% massiver :)
    – GEdgar
    Jun 12, 2021 at 23:13
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    @nnnnnn 'Heavier' is definitely inappropriate. An object's mass is constant regardless of its environment, it's weight is a function of its mass and the gravitational field in which it finds itself. Thus a space vehicle on the Moon or Mars weighs less than it did on Earth. However an object in orbit is in free fall so has no weight (only mass). All items in orbit weigh nothing whether they are pieces of space debris in orbit around the Earth, The Earth or Saturn orbiting the Sun or Titan orbiting Saturn. 'More massive' is the correct way to compare Titan to our moon.
    – BoldBen
    Jun 12, 2021 at 23:20

1 Answer 1


Massive is pedantically correct, and probably the standard in scientific circumstances. Especially when you are specifically talking about mass and not weight, which is usually an important distinction.

Another way of phrasing it could be “Titan is 50% larger than Earth's moon and has 80% more mass.”

Mass - More massive Weight - Heavier Volume - Larger

  • One presumes that larger means 'has greater volume', so you can be precise and compare volume to mass, which puts the comparison clearly without resorting to comparatives with percentages: Titan has 1.5 times the volume of Earth's moon, and 1.8 times its mass. May 18, 2020 at 20:08
  • Perhaps ironically, @JohnLawler, the "50% larger ... 80% more massive" construction may have been used to avoid using the "1.5 times the volume...1.8 times its mass" formula you propose in the interests of readability. (I think that people generally hate reading anything that sounds like a math problem, but they connect more to the percentages commonly touted in commercial media.)
    – RobJarvis
    Jun 17, 2020 at 21:15
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    Why "pedantically"? I find "more massive" here completely ordinary, run of the mill, and clear. (And I'm no astrophysicist.)
    – Drew
    Feb 12, 2021 at 21:17
  • This is not relevant to the core of the question, but it should be noted that '50% larger' is ambiguous between having 1.5 times the volume and having 1.5 times the diameter. In some contexts, other interpretations may also be possible.
    – jsw29
    Jun 13, 2021 at 20:20
  • But it could also be the surface area, the formula for which is 4πr2 (the 2 should be a superscript), from which the formula for volume is derived: V=4/3 πr3 (the 3 should be a superscript). The initial variable is r, and that is what NASA uses when comparing planets. ttps://solarsystem.nasa.gov/resources/686/solar-system-sizes/ However, when comparing moons, they seem to use diameter: nasa.gov/mission_pages/msl/multimedia/pia17351.html My money is on larger "diameter," which seems adequate for a visual comparison.
    – Zan700
    Jun 7, 2022 at 23:53

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