# Let's say I drill a hole through the Moon, and drop a golf ball into it **URL:** \ **Category:** Factual Questions\ **Created:** [November 5, 2011, 2:11am UTC](https://boards.straightdope.com/t/lets-say-i-drill-a-hole-through-the-moon-and-drop-a-golf-ball-into-it/601921 "2011-11-05T02:11:09Z")\ **Posts on this page:** 15\ **Page:** 2
**Author:** ![automagic](https://avatars.discourse-cdn.com/v4/letter/a/a698b9/32.png) [@automagic](https://boards.straightdope.com/u/automagic)\ **Post date:** [November 5, 2011, 1:36pm UTC](https://boards.straightdope.com/t/lets-say-i-drill-a-hole-through-the-moon-and-drop-a-golf-ball-into-it/601921/21 "2011-11-05T13:36:21Z")
> [@notsoheavyd3](#): > > Ok, I’ve been think about this a bit more and as far as I can tell it’s totally not going to work. If I drilled a hole from the near side to the far side in the middle of the disc at the equator I have a bit of a problem. The moon rotates once every 29.5 days and the circumference is about 6800 miles. That means at the top of the hole the hole and the ball are both moving sideways at about 10 miles per hour. However as you go down the hole the hole is moving sideways at a speed slower than that so the ball hits the side on the way down. Basically in order to stay in the tunnel at all points the ball’s sideway(translational) speed needs to match the hole and I think the geometry just won’t let that work. (Hell the hole on the other side is moving in the opposite direction. If the ball was in an orbit then gravity could reverse the direction but we don’t have the option here.) > > Of course if we have a non rotating moon it might be possible. I think that problem might be solved if the hole were to be drilled from pole to pole (aka its axis of rotation). Of course if its axis of rotation were to wobble during its rotation then we have another problem. ---
**Author:** ![jjimm](https://avatars.discourse-cdn.com/v4/letter/j/ba8739/32.png) [@jjimm](https://boards.straightdope.com/u/jjimm)\ **Post date:** [November 5, 2011, 2:05pm UTC](https://boards.straightdope.com/t/lets-say-i-drill-a-hole-through-the-moon-and-drop-a-golf-ball-into-it/601921/22 "2011-11-05T14:05:24Z")
> [@automagic](#): > > I think that problem might be solved if the hole were to be drilled from pole to pole (aka its axis of rotation). Of course if its axis of rotation were to wobble during its rotation then we have another problem. Isn’t the Moon’s axis of rotation the centre of the earth? ---
**Author:** ![Colophon](https://avatars.discourse-cdn.com/v4/letter/c/f05b48/32.png) [@Colophon](https://boards.straightdope.com/u/Colophon)\ **Post date:** [November 5, 2011, 2:07pm UTC](https://boards.straightdope.com/t/lets-say-i-drill-a-hole-through-the-moon-and-drop-a-golf-ball-into-it/601921/23 "2011-11-05T14:07:14Z")
> [@automagic](#): > > I think that problem might be solved if the hole were to be drilled from pole to pole (aka its axis of rotation). Of course if its axis of rotation were to wobble during its rotation then we have another problem. The OP did specify pole-to-pole. > [@](#): > > What would happen if I drilled a, say, one foot diameter hole through the Moon, from pole to pole. ---
**Author:** ![Napier](https://avatars.discourse-cdn.com/v4/letter/n/ce73a5/32.png) [@Napier](https://boards.straightdope.com/u/Napier)\ **Post date:** [November 5, 2011, 10:21pm UTC](https://boards.straightdope.com/t/lets-say-i-drill-a-hole-through-the-moon-and-drop-a-golf-ball-into-it/601921/24 "2011-11-05T22:21:51Z")
This would never work. Astronauts would keep hitting the golf balls before you could get them into the hole. I never did quite get why, but they’re always doing that. ---
**Author:** ![Leo\_Bloom](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leo_bloom/32/10377_2.png) [@Leo\_Bloom](https://boards.straightdope.com/u/Leo_Bloom)\ **Post date:** [November 6, 2011, 1:53am UTC](https://boards.straightdope.com/t/lets-say-i-drill-a-hole-through-the-moon-and-drop-a-golf-ball-into-it/601921/25 "2011-11-06T01:53:27Z")
> [@automagic](#): > > I think that problem might be solved if the hole were to be drilled from pole to pole (aka its axis of rotation). … Proposed in OP. ETA: Should read to end of thread first..:smack: ---
**Author:** ![appleciders](https://avatars.discourse-cdn.com/v4/letter/a/85f322/32.png) [@appleciders](https://boards.straightdope.com/u/appleciders)\ **Post date:** [November 6, 2011, 3:58am UTC](https://boards.straightdope.com/t/lets-say-i-drill-a-hole-through-the-moon-and-drop-a-golf-ball-into-it/601921/26 "2011-11-06T03:58:32Z")
> [@Little\_Nemo](#): > > There’s one other factor I think would exist even in an ideal system. Gravity is a two way attraction. While the moon is pulling the golf ball around much more noticeably, the golf ball is also pulling the moon towards itself. As the golf ball moves it’s minutely dragging the moon along with it. I believe the net effect of this over a few billion years would be to synchronize their movement with the golf ball motionless in the center of the moon. That’s not how Newtonian mechanics works. The moon accelerates the ball, and the ball accelerates the moon. There is no loss of energy through this process. > [@Boyo\_Jim](#): > > IIRC, the moon is slowly pulling away from the earth. Is this a gravitational effect, or due to orbital velocity? If the latter, will it eventually reach equilibrium? > > In either case, I think this would result in an eventual collision between the ball and the wall. The moon is pulling away from from the Earth because of gravitational forces. It’s complex, and it has to do with the Earth’s tides. Basically, the moon is sucking Earth’s rotational energy away as orbital velocity. The Earth is rotating more slowly, and the moon moves further away from the Earth. I can’t imagine why this would cause the ball to hit the wall, though. > [@notsoheavyd3](#): > > Ok, I’ve been think about this a bit more and as far as I can tell it’s totally not going to work. If I drilled a hole from the near side to the far side in the middle of the disc at the equator I have a bit of a problem. The moon rotates once every 29.5 days and the circumference is about 6800 miles. That means at the top of the hole the hole and the ball are both moving sideways at about 10 miles per hour. However as you go down the hole the hole is moving sideways at a speed slower than that so the ball hits the side on the way down. Basically in order to stay in the tunnel at all points the ball’s sideway(translational) speed needs to match the hole and I think the geometry just won’t let that work. (Hell the hole on the other side is moving in the opposite direction. If the ball was in an orbit then gravity could reverse the direction but we don’t have the option here.) > > Of course if we have a non rotating moon it might be possible. I’m not sure about this. I wonder if the ball would retain the rotational energy from the surface of the moon, and so not hit the wall. Like I said, though, I’m not sure, and it might. ---
**Author:** ![cmyk](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cmyk/32/3353_2.png) [@cmyk](https://boards.straightdope.com/u/cmyk)\ **Post date:** [November 6, 2011, 4:13am UTC](https://boards.straightdope.com/t/lets-say-i-drill-a-hole-through-the-moon-and-drop-a-golf-ball-into-it/601921/27 "2011-11-06T04:13:29Z")
> [@jjimm](#): > > Isn’t the Moon’s axis of rotation the centre of the earth? No, it’s just in a synchronous rotation with the earth (keeping one side locked facing earth). It still turns on its [own axis,](http://en.wikipedia.org/wiki/File:Earth-Moon.PNG) one revolution about every 27.3 days (as opposed to earth’s 23 hours, 56 minutes). ---
**Author:** ![Napier](https://avatars.discourse-cdn.com/v4/letter/n/ce73a5/32.png) [@Napier](https://boards.straightdope.com/u/Napier)\ **Post date:** [November 7, 2011, 3:44am UTC](https://boards.straightdope.com/t/lets-say-i-drill-a-hole-through-the-moon-and-drop-a-golf-ball-into-it/601921/28 "2011-11-07T03:44:04Z")
> [@jjimm](#): > > Isn’t the Moon’s axis of rotation the centre of the earth? It doesn’t even revolve around the Earth, much less rotate about it. I don’t know how the idea got started that the Moon revolves around the Earth, but the Earth and Moon are 400 times further away from the Sun than they are from each other. It is pretty accurate to say the Earth and Moon maintain a constant separation and the system rotates in local space around a point on this separation axis but very much closer to the Earth end of this axis. Then the whole system revolves around the Sun at a much larger constant separation. There are about 12 Earth-Moon system rotations for every Earth/Moon - Sun system rotation. The Moon therefore moves in a circular path around the sun, which varies in radius by about 1/4%, with 12 more distant spots and 12 less distant spots spaced around the circle. You would never see the deviation from a perfect circle if you could look down on this from above. In fact you would have to draw a big circle with a sharp pencil to not have the deviation hide within the thickness of the line. There are all sorts of other deviations from the ideal I describe, but they are all small relative to the issue of whether the Moon is circling the Sun or the Earth. The Moon’s path is always concave toward the Sun. It looks very much like a circle. ---
**Author:** ![BigT](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bigt/32/12044_2.png) [@BigT](https://boards.straightdope.com/u/BigT)\ **Post date:** [November 7, 2011, 8:41pm UTC](https://boards.straightdope.com/t/lets-say-i-drill-a-hole-through-the-moon-and-drop-a-golf-ball-into-it/601921/29 "2011-11-07T20:41:06Z")
> [@Napier](#): > > I don’t know how the idea got started that the Moon revolves around the Earth, And I don’t know why people think it doesn’t. The Moon’s path around a stationary Earth deviates even less than that of a stationary Sun. That pencil-width you talk about is a rather large amount of space, bigger than the Earth itself. At best you can argue that the Moon orbits both the Earth and the Sun, depending on your point of reference. ---
**Author:** ![nd\_n8](https://avatars.discourse-cdn.com/v4/letter/n/439d5e/32.png) [@nd\_n8](https://boards.straightdope.com/u/nd_n8)\ **Post date:** [November 8, 2011, 3:13pm UTC](https://boards.straightdope.com/t/lets-say-i-drill-a-hole-through-the-moon-and-drop-a-golf-ball-into-it/601921/30 "2011-11-08T15:13:10Z")
> [@BigT](#): > > And I don’t know why people think it doesn’t. The Moon’s path around a stationary Earth deviates even less than that of a stationary Sun. That pencil-width you talk about is a rather large amount of space, bigger than the Earth itself. > > At best you can argue that the Moon orbits both the Earth and the Sun, depending on your point of reference. That’s all crap. Everyone knows the Sun, the Earth and the Moon all orbit Chuck Norris. ---
**Author:** ![Irishman](https://avatars.discourse-cdn.com/v4/letter/i/b487fb/32.png) [@Irishman](https://boards.straightdope.com/u/Irishman)\ **Post date:** [November 8, 2011, 4:21pm UTC](https://boards.straightdope.com/t/lets-say-i-drill-a-hole-through-the-moon-and-drop-a-golf-ball-into-it/601921/31 "2011-11-08T16:21:15Z")
> [@jjimm](#): > > Isn’t the Moon’s axis of rotation the centre of the earth? Nope, the Moon’s axis of rotation is such that the Moon rotates 1 time per approx 28 days. It keeps essentially the same face toward the Earth, but it does it while going around the Earth. When it is on the side closest to the Sun, the side toward Earth is away from the Sun. When the Moon is on the far side of Earth from the Sun, the side toward Earth faces the Sun. The only way for this to happen is for the Moon to turn with respect to the Sun. And yes, there is a slight wobble, called libration. I am not certain how wobbly the axis is. > [@Napier](#): > > I don’t know how the idea got started that the Moon revolves around the Earth, Maybe the same was the idea got started that the Sun revolved around the Earth? > [@](#): > > The Moon therefore moves in a circular path around the sun, which varies in radius by about 1/4%, with 12 more distant spots and 12 less distant spots spaced around the circle. You would never see the deviation from a perfect circle if you could look down on this from above. In fact you would have to draw a big circle with a sharp pencil to not have the deviation hide within the thickness of the line. And yet it does so in a way that it is at different times in front of Earth, behind Earth, between the Earth and the Sun, and on the far side of the Earth from the Sun. That is a pretty good definition of revolving around the Earth. To be pedantic, yes the Earth and Moon are each revolving about a point somewhere between the two, but there’s still a trading places occurring. ---
**Author:** ![ruh-roh](https://avatars.discourse-cdn.com/v4/letter/r/8797f3/32.png) [@ruh-roh](https://boards.straightdope.com/u/ruh-roh)\ **Post date:** [November 8, 2011, 9:33pm UTC](https://boards.straightdope.com/t/lets-say-i-drill-a-hole-through-the-moon-and-drop-a-golf-ball-into-it/601921/32 "2011-11-08T21:33:59Z")
It seems to me that the OP has postulated a thought experiment, and to give that experiment substance has given the example of a hole through the moon and a golf ball. Everybody has jumped on the effects of that specific example. I think the more holistic question would be simply: How does an object move in a gravitational field, specifically if it is moving through the center of mass, and hence the center of the gravity field. So, to re-word the op’s question: If you have an object that is moving through the center of a gravitational field with no influences by other sources, what happens? I’m always amazed at how every space based sci-fi story ever told (or filmed) always seems to have complete control over gravity. Artificial gravity in the space ships, and ships that can hover with ‘anti-gravity’ in a gravitational field. They just take it for granted. HEY… if you can do that, you can, dare I say it, TAKE OVER THE UNIVERSE, no matter what the problems of the plot line are. ---
**Author:** ![Snarky\_Kong](https://avatars.discourse-cdn.com/v4/letter/s/a183cd/32.png) [@Snarky\_Kong](https://boards.straightdope.com/u/Snarky_Kong)\ **Post date:** [November 8, 2011, 9:47pm UTC](https://boards.straightdope.com/t/lets-say-i-drill-a-hole-through-the-moon-and-drop-a-golf-ball-into-it/601921/33 "2011-11-08T21:47:13Z")
> [@ruh-roh](#): > > It seems to me that the OP has postulated a thought experiment, and to give that experiment substance has given the example of a hole through the moon and a golf ball. Everybody has jumped on the effects of that specific example. I think the more holistic question would be simply: How does an object move in a gravitational field, specifically if it is moving through the center of mass, and hence the center of the gravity field. > > So, to re-word the op’s question: If you have an object that is moving through the center of a gravitational field with no influences by other sources, what happens? > > I’m always amazed at how every space based sci-fi story ever told (or filmed) always seems to have complete control over gravity. Artificial gravity in the space ships, and ships that can hover with ‘anti-gravity’ in a gravitational field. They just take it for granted. HEY.. if you can do that, you can, dare I say it, TAKE OVER THE UNIVERSE, no matter what the problems of the plot line are. Artificial gravity is easy. Drunk homeless people conjur it up all the time at town fairs. ---
**Author:** ![Andy\_L](https://avatars.discourse-cdn.com/v4/letter/a/c67d28/32.png) [@Andy\_L](https://boards.straightdope.com/u/Andy_L)\ **Post date:** [November 8, 2011, 9:54pm UTC](https://boards.straightdope.com/t/lets-say-i-drill-a-hole-through-the-moon-and-drop-a-golf-ball-into-it/601921/34 "2011-11-08T21:54:24Z")
> [@ruh-roh](#): > > It seems to me that the OP has postulated a thought experiment, and to give that experiment substance has given the example of a hole through the moon and a golf ball. Everybody has jumped on the effects of that specific example. I think the more holistic question would be simply: How does an object move in a gravitational field, specifically if it is moving through the center of mass, and hence the center of the gravity field. > > So, to re-word the op’s question: If you have an object that is moving through the center of a gravitational field with no influences by other sources, what happens? The OP gives the answer to that - simple harmonic motion from the surface to the center to the opposite surface and back again, over and over (subject to the extremely weak damping effects I mentioned in my first post). Cecil has a column on it [What if you fell into a tube through the earth? - The Straight Dope](http://www.straightdope.com/columns/read/154/what-if-you-fell-into-a-tube-through-the-earth) ---
**Author:** ![Leaffan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leaffan/32/299_2.png) [@Leaffan](https://boards.straightdope.com/u/Leaffan)\ **Post date:** [November 9, 2011, 2:06am UTC](https://boards.straightdope.com/t/lets-say-i-drill-a-hole-through-the-moon-and-drop-a-golf-ball-into-it/601921/35 "2011-11-09T02:06:09Z")
> [@Andy\_L](#): > > The OP gives the answer to that - simple harmonic motion from the surface to the center to the opposite surface and back again, over and over (subject to the extremely weak damping effects I mentioned in my first post). Cecil has a column on it [What if you fell into a tube through the earth? - The Straight Dope](http://www.straightdope.com/columns/read/154/what-if-you-fell-into-a-tube-through-the-earth) I believe this answers my question. But no reason to keep the thread going for other ancillary ideas and questions. [Previous page](https://boards.straightdope.com/t/lets-say-i-drill-a-hole-through-the-moon-and-drop-a-golf-ball-into-it/601921.md?page=1)