# Darts on the Moon

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#### dartoid

##### Guest
I am hoping some of you can help me. I have never posted before...<br /><br />For the past dozen years or so I have written a syndicated humor column about darts. The column is the most widely read of its kind and is carried in numerous countries.<br /><br />I am beginning research on a story about what it would be like to throw darts on the moon. <br /><br />Here's the scenario. The dart weighs 24 grams. The board is 7' 9 1/4 inches from the throwing line (oche) and the center of the board (bull) is 5' 8" from the floor.<br /><br />Can anyone out there help me understand what would happen, how it would feel -- to throw a dart under such conditions in zero gravity (on the moon). For example, how fast might the dart fly? If it missed the board, how far woud it travel? How heavy would a 24 gram dart be on the moon?<br /><br />I know such questions may sound ridiculous. Perhaps you can cut me some slack. I dropped out of Algebra in 10th grade and blew up my Bunsen Burner in science. <br /><br />Thanks for any help any of you can help me in building this story.<br /><br />Dartoid

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#### najab

##### Guest
><i>Can anyone out there help me understand what would happen, how it would feel -- to throw a dart under such conditions in zero gravity (on the moon).</i><p>Methinks you need to do some more research! There is gravity on the Moon, it's just less than on Earth - 1/6 to be more exact. So in that regard it wouldn't be any different to throwing a dart on Earth, except tha the dart would go about 6 times further before it hit the floor<p>The lack of an appreciable atmosphere would make a <b>huge</b> difference to darts however. With no air to act on the flight, the dart would travel in whatever orientation it was in when it left your hand - if you threw it flight first, it would hit the board flight first. I think this would make your game of darts difficult, if not impossible as I don't think there are many players who throw the dart exactly perpendicular to the board.</p></p>

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#### emperor_of_localgroup

##### Guest
Just a slight correction, najaB. It would travel only 2.45 times farther, not 6 times. Because of a square root. <br /><br />Other than that what najaB said about motion is alright. The dart will go horizontally much straighter on the moon than on earth. <div class="Discussion_UserSignature"> <font size="2" color="#ff0000"><strong>Earth is Boring</strong></font> </div>

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#### jindivik

##### Guest
i dont think it would go any faster either? unless you can move your arm faster on the moon (which would be rather difficult in a bulky space suit)

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*doh*

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#### bobvanx

##### Guest
>bulky space suit<br /><br />I'd hate to have a mishap and tear a hole in my suit.<br /><br />Perhaps this dart game is conducted within a pressurized volume. In which case, the darts would get oriented to the board through their aerodynamics, the trajectory would be very flat, and seasoned throwers could be differentiated from kooks because neophytes would tend to throw too hard. Throwing too hard would tend to make people fall down, since their inertia is still the same, but their contact with the floor is 1/6th as strong.<br /><br />Sitting in a swivel chair with your feet off the floor and tossing darts would be a way to practise for lunar dart throwing.

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#### bobw

##### Guest
A good way to practice for moon darts on earth could be to hang one dartboard above another. Aim at the top board and count your score off the bottom one and when you get to the moon the dart will fall less and go where you have practiced aiming. <div class="Discussion_UserSignature"> </div>

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#### mrmorris

##### Guest
<font color="yellow">"...to hang one dartboard above another."</font><br /><br />Um -- don't know if you were kidding. No smileyface, so I assume not. In darts, you're only 8-ish feet from the board and flight times are on the order of 1/5th of a second. In 1G a free-falling object would drop ~20 cm, and in 1/6th G it would drop ~3 cm. So the maximum difference would be on the order of ~17 cm (~6.7 in) assuming no aerodynamic 'lift' effects from the dart's flight.<br /><br />So there's a few problems. <br /><br />One -- that's a *lot* less than the diameter of a dartboard, so the top/bottom concept isn't really feasible.<br /><br />Two -- the concept itself is flawed. If you aim at the top board on Earth -- that's where you'll hit -- unless you're a really bad player. You can't use the lower board for scoring purposes. You <b>can</b> practice aiming lower than you normally would and simply add a predefined 'fudge-factor' (i.e. 17cm) to the dart's ending location to determine where to score it.<br /><br />Three -- since the darts will fall *more* on Earth and *less* on the Moon -- even if it would work -- you'd want to practice aiming <b>lower</b> than you normally would, not higher.

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#### bobw

##### Guest
Maybe I am so bad at darts because I throw way too slow <img src="/images/icons/smile.gif" /> I figgured it would be hard to aim one place and score another. <div class="Discussion_UserSignature"> </div>

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#### tony873004

##### Guest
If you stood on the Moon's equator and threw the dart level to the ground, east or west at 1700 meters / second, the dart would hit you in the back 1 hour 50 minutes later.

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#### mrmorris

##### Guest
<font color="yellow">"If you stood on the Moon's equator..."</font><br /><br />Among other things -- you might change that to: 'If you stood on the highest point of the Moon's equator...'. Otherwise, you're almost certain to hit a terrain feature somewhere along that path.<br /><br />Also -- assuming an orbit at ground level (~1,738,000 meters from the center of the moon), the orbital period would be ~108 minutes (a 110 minute period would be at a height of about 17 km above the surface of the moon). You're pretty close on the velocity though -- ~1685 meters per second.

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#### igorsboss

##### Guest
Another correction...<br /><br /><font color="yellow">The lack of an appreciable atmosphere would make a huge difference to darts however. With no air to act on the flight, the dart would travel in whatever orientation it was in when it left your hand - if you threw it flight first, it would hit the board flight first. I think this would make your game of darts difficult, if not impossible as I don't think there are many players who throw the dart exactly perpendicular to the board.</font><br /><br />If the dart was thrown with spin, the dart would tumble in flight. The dart's orientation would depend on the original orientation, the spin direction and (angular) velocity, and the time of flight.<br /><br />A dart could be thrown flight first, tumble end-over-end, and strike the board point-first, for exmple. However, if the tumble was too rapid or too slow, the dart would strike the board side-first. This would resemble a tomahawk (or axe) throw.<br /><br />http://www.inquiry.net/outdoor/skills/beard/throw_tomahawk.htm<br /><br />With a traditional dart-shape, the thrower might choose to spin-stabilize the dart. If the dart were thrown point first, with a rapid spin along the long axis of the dart, the dart would hit the board point-first every time. This type of throw would resemble an (american) football spiral.

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#### igorsboss

##### Guest
Whatever you do, don't go painting a dartboard on the thin aluminum side of your lunar lander.<br /><br />"Gosh, it was airtight when we landed!"

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#### dartoid

##### Guest
I just want to say THANKYOU to everybody who has participated in this discussion so far. Please keep it going a while loker. Your insights (and humor) are both outstanding and helpful. I truly appreciate it -- and promise to retunr the favor by eventually posting the column I write at this forum.

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#### najab

##### Guest
Yeah, I thought about a tumbling dart, but decided to leave it out, since most players tend not to do that.

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#### igorsboss

##### Guest
<font color="yellow">I thought about a tumbling dart, but decided to leave it out, since most players tend not to do that.</font><br /><br />The flights mask the fact that most players actually do cause their darts to tumble.<br /><br />Come to think of it, does it really make any sense to play darts in a vaccuum, in a full spacesuit? What a tremendously dangerous game that would be!<br /><br />Young Frankenstein: "Nice Grouping!"

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#### najab

##### Guest
I'd like to think that inside or out, there's gotta be better things to do on the Moon than play darts. <img src="/images/icons/tongue.gif" />

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#### mrmorris

##### Guest
<font color="yellow">"...better things to do on the Moon than play darts. "</font><br /><br />Pool? Gonna be hard to keep those balls on the felt*... <br /><br /><br /><img src="/images/icons/smile.gif" /><br /><br /><br />* The 'break' is going to take on a whole new meaning to anyone else unfortunate enough to be in the lunar habitat.

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#### CalliArcale

##### Guest
Oh, that really puts some funny images in my mind. <img src="/images/icons/wink.gif" /> <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>

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#### mrmorris

##### Guest
<font color="yellow">"Daedalus anyone? "</font><br /><br />I: Stay in the middle of the chamber, Daedalus. Don't get too near the ceiling with those 1000W Halogen lights!<br />D: Oooh... pretty lights... *ZAP* AAAAiiiieeeeeee.

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#### nacnud

##### Guest
Clarke had a good sectionin one of his books about flight in air on the moon, I'll look it up.

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#### dartoid

##### Guest
I have been away for the past few days and am just now catching up on your input to my question. Tnanks again to all of you. It appears I need to be a bit more specific...<br /><br />My column envisions throwing darts outside, not inside. So, in addition to the effects of gravity and so on, what might it look like? What will I see? Is it light, dark? Does it rain. Etc. I gather that the dart will feel less heavy and fly straighter and essentially forever, if nothing blocks its flight, but at 1/6 Earth's gravity will it not eventually hit the ground -- as opposed to returning to hit me in the back (as in the one example above -- and how fast in miles per hour is 1700 meters per second)? What will I have to wear? What's a spacesuit cost? What did the last manned flight to the moon cost and how long did it take to get there? How far away is the moon? I seem to recall that someone once hit a golf ball on the moon -- where would that ball be now; is it still flying in space somewhere? If I drank a six-pack of Budweiser on the moon would it effect me differently than on Earth? What would happen if I lit a cigarette? What would happen if I took off my spacesuit? If a dart hits a wire on the board but bounces off, is it lost forever? How will it feel to walk back and forth to the board -- will it be easier or more laborious? Does the female breast sag only 1/6 as much on the moon???? Do I have any volunteers to go with me? Seriously, I know nothing about any of this and sincerely appreciate all of your input. I promise to post the column here when it is completed and, of course, to acknowledge your input when it it published. Thank you again and sorry for asking what to all of you must seem to be inanely stupid questions!

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#### najab

##### Guest
Wow, a lot of questions! I'll answer the ones I can, I'm sure others will chip in:<br /><br /><font color="yellow">So, in addition to the effects of gravity and so on, what might it look like?</font><br /><br />The Moon has been described in various ways by the Apollo astronauts - "magnificent desolation" (Lovell?) is probably the most apt. "Miles and miles of grey beach sand" (Borman?) is another. Scott was all for "the exploration of beautiful places". It really is the kind of landscape that affects everyone who sees it in a different way.<br /><br /><font color="yellow">What will I see? Is it light, dark? </font><br />Yes. It is light and dark - contrary to the popular misconception, there is no "Dark Side" of the Moon. The Moon has day and night, just like here on Earth, the only difference is that its revolution and rotation period are the same, which means that the day is 14 Earth days long, as is its night.<br /><br /><font color="yellow">Does it rain?</font><br />No. Clouds, rain and duststorms are products of a significant atmosphere.The Moon does have a very tenous atmosphere, but it isn't thick enough to produce any meteorological effects, nor to fly any rotary wing vehicles <img src="/images/icons/smile.gif" /><br /><br /><font color="yellow">I gather that the dart will feel less heavy and fly straighter and essentially forever, if nothing blocks its flight, but at 1/6 Earth's gravity will it not eventually hit the ground -- as opposed to returning to hit me in the back (as in the one example above -- and how fast in miles per hour is 1700 meters per second)?</font><br /><br />It won't fly forever, as you pointed out, since on the Moon there <b>IS</b> gravity. The dart will go about twice as far on the Moon as it would on Earth. 1.7 kilometers is <i>slightly</i> more than 1 mile, so 1.7km

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#### CalliArcale

##### Guest
Excellent answers, but I'd like to supplement them a little. <img src="/images/icons/wink.gif" /><br /><br /><b><font color="yellow">What will I see? Is it light, dark?</font><br />Yes. It is light and dark - contrary to the popular misconception, there is no "Dark Side" of the Moon. The Moon has day and night, just like here on Earth, the only difference is that its revolution and rotation period are the same, which means that the day is 14 Earth days long, as is its night. </b><br /><br />If it is daytime, you will see the Moon's surface. It is bright, with lots of glassy particles in the regolith to reflect sunlight. This will wash out any stars in the sky, because your eyes will adjust to the brightness of the lunar surface. But the sky will be black, because there is no air to diffuse it. If you're on the nearside (the side facing Earth), you'll see the Earth in the sky, about twice as wide as the Moon appears from here. The phase of the Earth will depend on the phase of the Moon; if Earth observers are seeing the full moon, you will see only a very thin crescent Earth -- or possibly no Earth at all. If you are lucky enough to be there during a lunar eclipse, you'll see the Earth eclipse the Sun! If it is a half-moon for observers on Earth, you will see a half Earth.<br /><br />If it is nighttime and you are on the Moon's farside, you will be on an absolutely pitch-black surface underneath a star-studded night sky that would make any astronomer drool with excitement. <img src="/images/icons/smile.gif" /> It will be better than the stars as seen from the top of a very high mountain at night. If you are on the nearside, however, it won't be quite so dark. The Earth will most likely be better than half full, which will cast a lot of light. (The Earth is not only bigger but also a lot more reflective than the Moon. You can see by moonlight, so you'd see even better by earthlight.) If Earth observers are seeing a new moon (i.e. not seeing the moon at <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>

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