# if you have the ISS circle a globe, it's orbit is 1/16 of an inch above the surface. ? **URL:** \ **Category:** Factual Questions\ **Created:** [November 26, 2013, 4:23pm UTC](https://boards.straightdope.com/t/if-you-have-the-iss-circle-a-globe-its-orbit-is-1-16-of-an-inch-above-the-surface/674832 "2013-11-26T16:23:13Z")\ **Posts on this page:** 14\ **Page:** 1
**Author:** ![jharvey963](https://avatars.discourse-cdn.com/v4/letter/j/54ee81/32.png) [@jharvey963](https://boards.straightdope.com/u/jharvey963)\ **Post date:** [November 26, 2013, 4:23pm UTC](https://boards.straightdope.com/t/if-you-have-the-iss-circle-a-globe-its-orbit-is-1-16-of-an-inch-above-the-surface/674832/1 "2013-11-26T16:23:13Z")
I heard Neil DeGrasse Tyson say something like this: “If you take a globe and imagine the ISS orbiting around the globe, it’s height above the globe surface would be 1/16 of an inch.” He didn’t specify the size of the globe. Now, my addled brain couldn’t get the math to work to see if this is true. My assumptions: the ISS is 230 miles above the surface of the earth. The earth’s radius is 4000 miles (approx.). So, is this true? How big would the globe have to be to make this true? And what is the math (simplified!) to show this is true? Thanks, Jeff ---
**Author:** ![UncleRojelio](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/unclerojelio/32/3160_2.png) [@UncleRojelio](https://boards.straightdope.com/u/UncleRojelio)\ **Post date:** [November 26, 2013, 4:27pm UTC](https://boards.straightdope.com/t/if-you-have-the-iss-circle-a-globe-its-orbit-is-1-16-of-an-inch-above-the-surface/674832/2 "2013-11-26T16:27:25Z")
.0625/x = 230/4000, x = 1 inch. ---
**Author:** ![yellowjacketcoder](https://avatars.discourse-cdn.com/v4/letter/y/4bbf92/32.png) [@yellowjacketcoder](https://boards.straightdope.com/u/yellowjacketcoder)\ **Post date:** [November 26, 2013, 4:29pm UTC](https://boards.straightdope.com/t/if-you-have-the-iss-circle-a-globe-its-orbit-is-1-16-of-an-inch-above-the-surface/674832/3 "2013-11-26T16:29:11Z")
First, let’s convert units. If the ISS is 230 miles above the Earth, that’s 230 \* 5280 \* 12 = 14572800 inches If the Earth’s radius is 4000 miles, that’s 4000 \* 5180 \* 12 = 253440000 inches. Therefore, the conversion factor is 16 \* 14572800 or 233164800 253440000 / 233164800 = 1.08, or about an inch and a sixteenth radius of the globe. That’s a pretty small globe, unless I fudged the numbers somewhere. Sounds like it should be even closer. ---
**Author:** ![bup](https://avatars.discourse-cdn.com/v4/letter/b/6bbea6/32.png) [@bup](https://boards.straightdope.com/u/bup)\ **Post date:** [November 26, 2013, 4:30pm UTC](https://boards.straightdope.com/t/if-you-have-the-iss-circle-a-globe-its-orbit-is-1-16-of-an-inch-above-the-surface/674832/4 "2013-11-26T16:30:37Z")
NM - mathed wrong. x/.0625 = 4000/230 x = 1.0869 inches. ---
**Author:** ![bup](https://avatars.discourse-cdn.com/v4/letter/b/6bbea6/32.png) [@bup](https://boards.straightdope.com/u/bup)\ **Post date:** [November 26, 2013, 4:49pm UTC](https://boards.straightdope.com/t/if-you-have-the-iss-circle-a-globe-its-orbit-is-1-16-of-an-inch-above-the-surface/674832/5 "2013-11-26T16:49:22Z")
A reasonable globe of 12" diameter, with a 6" radius, would have the ISS about .345" off the surface - somewhere between 5/16" and 3/8". ---
**Author:** ![garygnu](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/garygnu/32/2924_2.png) [@garygnu](https://boards.straightdope.com/u/garygnu)\ **Post date:** [November 26, 2013, 5:05pm UTC](https://boards.straightdope.com/t/if-you-have-the-iss-circle-a-globe-its-orbit-is-1-16-of-an-inch-above-the-surface/674832/6 "2013-11-26T17:05:57Z")
The radius of Earth is 3959 miles, and your run of the mill 12" globe has a radius of 6 inches. The radius of the ISS orbit is 4189 miles, so on that 12" globe it would be ~0.35 inches off the surface. 4189/3959=1.0581 6\*1.0581=6.3486 So more like three-eighths of an inch. (Ninja’d, but I’ll post anyway.) ---
**Author:** ![AlsoNamedBort](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/alsonamedbort/32/3213_2.png) [@AlsoNamedBort](https://boards.straightdope.com/u/AlsoNamedBort)\ **Post date:** [November 26, 2013, 5:57pm UTC](https://boards.straightdope.com/t/if-you-have-the-iss-circle-a-globe-its-orbit-is-1-16-of-an-inch-above-the-surface/674832/7 "2013-11-26T17:57:07Z")
> [@bup](#): > > A reasonable globe of 12" diameter, with a 6" radius, would have the ISS about .345" off the surface - somewhere between 5/16" and 3/8". It’s turns out, that’s pretty much what Tyson said: [http://blog.al.com/space-news/2010/12/astrophysicist\_neil\_degrasse\_t.html](http://blog.al.com/space-news/2010/12/astrophysicist_neil_degrasse_t.html) > [@](#): > > The target now is Mars, and Tyson used an analogy to show how far away it is. If the Earth were the size of a school room globe, he said, our atmosphere would be no thicker than the lacquer on the globe, the moon would be 30 feet away, and the International Space Station three-eighths of an inch away. Mars would be a mile away. ---
**Author:** ![KneadToKnow](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kneadtoknow/32/3999_2.png) [@KneadToKnow](https://boards.straightdope.com/u/KneadToKnow)\ **Post date:** [November 26, 2013, 6:05pm UTC](https://boards.straightdope.com/t/if-you-have-the-iss-circle-a-globe-its-orbit-is-1-16-of-an-inch-above-the-surface/674832/8 "2013-11-26T18:05:59Z")
Using the 3/8" number for the ISS, how far out is geosynchronous orbit? Sorry, my math is in the shop this week. ---
**Author:** ![chrisk](https://avatars.discourse-cdn.com/v4/letter/c/6de8d8/32.png) [@chrisk](https://boards.straightdope.com/u/chrisk)\ **Post date:** [November 26, 2013, 6:11pm UTC](https://boards.straightdope.com/t/if-you-have-the-iss-circle-a-globe-its-orbit-is-1-16-of-an-inch-above-the-surface/674832/9 "2013-11-26T18:11:42Z")
Geostationary orbit is 22,236 miles above the surface. We were using 4189 for the ISS orbital height, so geostationary would be 5.3 times that, or almost exactly 2 inches! ---
**Author:** ![KneadToKnow](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kneadtoknow/32/3999_2.png) [@KneadToKnow](https://boards.straightdope.com/u/KneadToKnow)\ **Post date:** [November 26, 2013, 6:13pm UTC](https://boards.straightdope.com/t/if-you-have-the-iss-circle-a-globe-its-orbit-is-1-16-of-an-inch-above-the-surface/674832/10 "2013-11-26T18:13:30Z")
Sweet. Thanks, **chrisk**! ---
**Author:** ![BlinkingDuck](https://avatars.discourse-cdn.com/v4/letter/b/eada6e/32.png) [@BlinkingDuck](https://boards.straightdope.com/u/BlinkingDuck)\ **Post date:** [November 26, 2013, 6:15pm UTC](https://boards.straightdope.com/t/if-you-have-the-iss-circle-a-globe-its-orbit-is-1-16-of-an-inch-above-the-surface/674832/11 "2013-11-26T18:15:56Z")
> [@chrisk](#): > > Geostationary orbit is 22,236 miles above the surface. We were using 4189 for the ISS orbital height, so geostationary would be 5.3 times that, or almost exactly 2 inches! That doesn’t seem right… 22,236 miles divided by about 4000 mile radius would be about 5 and a half times the radius or about 2 and 3/4 feet ? ---
**Author:** ![chrisk](https://avatars.discourse-cdn.com/v4/letter/c/6de8d8/32.png) [@chrisk](https://boards.straightdope.com/u/chrisk)\ **Post date:** [November 26, 2013, 6:19pm UTC](https://boards.straightdope.com/t/if-you-have-the-iss-circle-a-globe-its-orbit-is-1-16-of-an-inch-above-the-surface/674832/12 "2013-11-26T18:19:13Z")
Whoops, sorry! Math only works if you plug in the correct numbers! :smack: 22236 / **230** \* (3/8) = 36.25 inches, or a little over three feet away! ---
**Author:** ![KneadToKnow](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kneadtoknow/32/3999_2.png) [@KneadToKnow](https://boards.straightdope.com/u/KneadToKnow)\ **Post date:** [November 26, 2013, 6:34pm UTC](https://boards.straightdope.com/t/if-you-have-the-iss-circle-a-globe-its-orbit-is-1-16-of-an-inch-above-the-surface/674832/13 "2013-11-26T18:34:19Z")
Ah! Even better! 🙂 ---
**Author:** ![Dog80](https://avatars.discourse-cdn.com/v4/letter/d/6bbea6/32.png) [@Dog80](https://boards.straightdope.com/u/Dog80)\ **Post date:** [November 26, 2013, 7:03pm UTC](https://boards.straightdope.com/t/if-you-have-the-iss-circle-a-globe-its-orbit-is-1-16-of-an-inch-above-the-surface/674832/14 "2013-11-26T19:03:14Z")
See here: [![](http://tinypic.com/images/goodbye.jpg) ](http://tinypic.com/images/goodbye.jpg) The white dot at the upper right corner represents an object at about 600km from the surface of the earth. The ISS is even closer than that at 300-400 km