PhysicsGeneralQuality 84 · Exceptional

Why Gravity Is Weaker on the Moon

PR
Mio Quigley Verified Teacher
@author · 2026-06-28 · v1
7 min read
Gravitational acceleration depends on mass and distance:
g=GM/r2g = GM/r^2
. The Moon has about 1/81 of Earth's mass and 1/4 of its radius, so its surface gravity is roughly 1.6 m/s² compared to Earth's 9.8 m/s². This is why astronauts could leap high despite wearing heavy suits — the downward pull was about six times weaker.
0 teacher endorsements

Discussion

Comments support LaTeX — write ∫01x2 dx\int_0^1 x^2\,dx inline with $...$.

Sign in to join the discussion.

Sofia Garcia
24 days ago
The line "Gravitational acceleration depends on mass and distance: g=GM/r2g = GM/r^2" is the part that finally made it click for me. I'd been fuzzy on gravitational before — seeing it spelled out this way connects it to acceleration in a way my notes never did. The g=gm/r2g = gm/r^2 bit is a nice touch too.
Mateo Rossi
24 days ago
Yeah, the gravitational point is exactly right. I'd add that acceleration matters here too — if you drop it, the astronauts case breaks down even though it *looks* optional. Learned that the hard way on a problem set last week.
Ethan Park
24 days ago
Quick question on gravitational: does that also explain what happens with acceleration? My textbook mentions both but never ties them together, and this explanation of astronauts makes me think they're the same mechanism from two angles.
Yuki Tanaka
24 days ago
Adding to this: "Gravitational acceleration depends on mass and distance: g=GM/r2g = GM/r^2" also generalizes to acceleration. I tried it on astronauts and the same logic holds, which makes me think gravitational is the deeper principle behind all of them. The g=gm/r2g = gm/r^2 detail is what trips people up though.
Olivia Murphy
24 days ago
What stood out is "The Moon has about 1/81 of Earth's mass and 1/4 of its radius, so its surface gravity is roughly 1.6 m/s² compared to Earth's 9.8 m/s²" — most resources skip the *why* and just give the formula. Adding acceleration to the picture is what makes gravitational feel like a real tool instead of trivia. Saved this one.