# What if I jumped off a cliff on the moon? **URL:** \ **Category:** Factual Questions\ **Created:** [January 5, 2004, 3:50pm UTC](https://boards.straightdope.com/t/what-if-i-jumped-off-a-cliff-on-the-moon/222822 "2004-01-05T15:50:20Z")\ **Posts on this page:** 13\ **Page:** 2
**Author:** ![av8rmike](https://avatars.discourse-cdn.com/v4/letter/a/edb3f5/32.png) [@av8rmike](https://boards.straightdope.com/u/av8rmike)\ **Post date:** [January 6, 2004, 4:23pm UTC](https://boards.straightdope.com/t/what-if-i-jumped-off-a-cliff-on-the-moon/222822/21 "2004-01-06T16:23:54Z")
If you can only jump off a 4-foot cliff on Earth without getting hurt. 😛 I think I’ve jumped further than that without injury. Also, **FoamFighter** , your location is confusing. Shouldn’t it be 39Âș 37’N, instead of 38Âș 97’N? On my map that puts you about 10 miles west of Prettyboy Reservoir. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [January 6, 2004, 4:34pm UTC](https://boards.straightdope.com/t/what-if-i-jumped-off-a-cliff-on-the-moon/222822/22 "2004-01-06T16:34:39Z")
Yes, also assuming that the lowered gravity didn’t cause you to misjudge your leap and land head-first or something. ---
**Author:** ![Agent\_Foxtrot](https://avatars.discourse-cdn.com/v4/letter/a/9fc29f/32.png) [@Agent\_Foxtrot](https://boards.straightdope.com/u/Agent_Foxtrot)\ **Post date:** [January 6, 2004, 6:25pm UTC](https://boards.straightdope.com/t/what-if-i-jumped-off-a-cliff-on-the-moon/222822/23 "2004-01-06T18:25:56Z")
> [@](#): > > \*Originally posted by av8rmike \* > \*\*If you can only jump off a 4-foot cliff on Earth without getting hurt. 😛 I think I’ve jumped further than that without injury. > > Also, **FoamFighter** , your location is confusing. Shouldn’t it be 39Âș 37’N, instead of 38Âș 97’N? On my map that puts you about 10 miles west of Prettyboy Reservoir. \*\* Actually, I live in Catonsville. 🙂 - Adam ---
**Author:** ![DanBlather](https://avatars.discourse-cdn.com/v4/letter/d/f4b2a3/32.png) [@DanBlather](https://boards.straightdope.com/u/DanBlather)\ **Post date:** [January 6, 2004, 9:21pm UTC](https://boards.straightdope.com/t/what-if-i-jumped-off-a-cliff-on-the-moon/222822/24 "2004-01-06T21:21:15Z")
You also need to keep in mind the mass of the space suit. That could easily double the energy of impact. Of course the suit could potentially give some “crush space” to decrease the de-accelleration (I know there is no such thing). ---
**Author:** ![rjk](https://avatars.discourse-cdn.com/v4/letter/r/ed655f/32.png) [@rjk](https://boards.straightdope.com/u/rjk)\ **Post date:** [January 7, 2004, 5:51am UTC](https://boards.straightdope.com/t/what-if-i-jumped-off-a-cliff-on-the-moon/222822/25 "2004-01-07T05:51:40Z")
> [@](#): > > \*Originally posted by ftg \* > **Since the Moon, like the Earth is hollow with openings at the poles (big smirk), if you fall into the North pole hole on the Moon, you will continue to accelerate until you reach the center, far faster than the escape velocity at surface.** No, not if the Moon is properly hollow, i.e. a relatively thin shell with relatively small openings at the poles. There’s no gravitational acceleration inside a spherical shell. If you’re off-centre, the attraction of the near side is balanced by the attraction of the greater mass (more area in your field of view!) on the far side. Unless you’re in Pellucidar. ---
**Author:** ![umop\_ap\_sdn](https://avatars.discourse-cdn.com/v4/letter/u/dbc845/32.png) [@umop\_ap\_sdn](https://boards.straightdope.com/u/umop_ap_sdn)\ **Post date:** [January 7, 2004, 8:36am UTC](https://boards.straightdope.com/t/what-if-i-jumped-off-a-cliff-on-the-moon/222822/26 "2004-01-07T08:36:18Z")
Once I fell 5 feet on to my back (in Earth gravity) and walked away; guess that means 30 feet on the Moon wouldn’t kill me. 😃 > [@](#): > > \*Originally posted by rjk \* > **If you’re off-centre, the attraction of the near side is balanced by the attraction of the greater mass (more area in your field of view!) on the far side.** Is that because they both obey the inverse square rule? ---
**Author:** ![Achernar](https://avatars.discourse-cdn.com/v4/letter/a/e274bd/32.png) [@Achernar](https://boards.straightdope.com/u/Achernar)\ **Post date:** [January 7, 2004, 8:39am UTC](https://boards.straightdope.com/t/what-if-i-jumped-off-a-cliff-on-the-moon/222822/27 "2004-01-07T08:39:56Z")
Yes. ---
**Author:** ![Achernar](https://avatars.discourse-cdn.com/v4/letter/a/e274bd/32.png) [@Achernar](https://boards.straightdope.com/u/Achernar)\ **Post date:** [January 7, 2004, 8:53am UTC](https://boards.straightdope.com/t/what-if-i-jumped-off-a-cliff-on-the-moon/222822/28 "2004-01-07T08:53:48Z")
Actually, that’s probably not the best way to say it, though I think you have the right idea. The amount of mass per solid angle goes as the square of the distance, and the amount of gravity force per mass goes as the inverse-square of the distance. So they cancel, and the gravity force per solid angle is constant with distance. (Solid angle is the measure of “field of view”.) ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [January 10, 2004, 12:05am UTC](https://boards.straightdope.com/t/what-if-i-jumped-off-a-cliff-on-the-moon/222822/29 "2004-01-10T00:05:30Z")
You don’t fall on the moon; you and the moon fall toward your shared centre of mass. ---
**Author:** ![umop\_ap\_sdn](https://avatars.discourse-cdn.com/v4/letter/u/dbc845/32.png) [@umop\_ap\_sdn](https://boards.straightdope.com/u/umop_ap_sdn)\ **Post date:** [January 10, 2004, 7:43am UTC](https://boards.straightdope.com/t/what-if-i-jumped-off-a-cliff-on-the-moon/222822/30 "2004-01-10T07:43:39Z")
Well that’s also true of Earth but in both cases the center of mass is so close to the center of the celestial body that for all practical purposes it makes no difference. For that matter, the Earth and Moon revolve around a common center of mass but that center stays a few thousand miles below the Earth’s surface at all times. ---
**Author:** ![a\_gherkin](https://avatars.discourse-cdn.com/v4/letter/a/f6c823/32.png) [@a\_gherkin](https://boards.straightdope.com/u/a_gherkin)\ **Post date:** [January 10, 2004, 3:03pm UTC](https://boards.straightdope.com/t/what-if-i-jumped-off-a-cliff-on-the-moon/222822/31 "2004-01-10T15:03:47Z")
i think, technically the original question is somewhat flawed, as the moon holds no water, therefore there are no coastal erosive processes taking place and therefore, strictly, no CLIFFS. but we all know what you mean. ---
**Author:** ![umop\_ap\_sdn](https://avatars.discourse-cdn.com/v4/letter/u/dbc845/32.png) [@umop\_ap\_sdn](https://boards.straightdope.com/u/umop_ap_sdn)\ **Post date:** [January 11, 2004, 6:06am UTC](https://boards.straightdope.com/t/what-if-i-jumped-off-a-cliff-on-the-moon/222822/32 "2004-01-11T06:06:40Z")
Well, according to [this site](http://www.physics.uq.edu.au/people/ross/phys2081/moon/moon.htm), the Moon has at least one cliff: > [@](#): > > With a small telescope such features as the straight wall, **a 250 metre high cliff** (fault?) and the Alpine valley, a gouge in the Alps (south of Mare Frigoris) become visible. That would be quite a fall though, and it’s doubtful anybody would survive it even in the Moon’s gravity. :eek: ---
**Author:** ![Agent\_Foxtrot](https://avatars.discourse-cdn.com/v4/letter/a/9fc29f/32.png) [@Agent\_Foxtrot](https://boards.straightdope.com/u/Agent_Foxtrot)\ **Post date:** [January 11, 2004, 6:43am UTC](https://boards.straightdope.com/t/what-if-i-jumped-off-a-cliff-on-the-moon/222822/33 "2004-01-11T06:43:28Z")
Even if there are no erosive processes on the moon, a sizable asteroid could create a nice gash in the surface. - Adam [Previous page](https://boards.straightdope.com/t/what-if-i-jumped-off-a-cliff-on-the-moon/222822.md?page=1)