# What's the longest, naturally-occurring straight edge, circle, and sphere? **URL:** \ **Category:** Factual Questions\ **Created:** [September 1, 2006, 3:18pm UTC](https://boards.straightdope.com/t/whats-the-longest-naturally-occurring-straight-edge-circle-and-sphere/371080 "2006-09-01T15:18:08Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Kidney](https://avatars.discourse-cdn.com/v4/letter/k/34f0e0/32.png) [@Kidney](https://boards.straightdope.com/u/Kidney)\ **Post date:** [September 1, 2006, 3:18pm UTC](https://boards.straightdope.com/t/whats-the-longest-naturally-occurring-straight-edge-circle-and-sphere/371080/1 "2006-09-01T15:18:08Z")
It is very unusual to find perfect circles or straight lines in nature. But are there any reasonably perfect approximations? The rules are as follows: [ul]It has to naturally occuring–not man made. [/ul] [ul]It has to occur as a repeatable natural process. A single, unique object wouldn’t count. [/ul] [ul]It has to be durable. Something that could be held without deforming it. So things like bubbles and spider silk wouldn’t count.[/ul] [ul]Perfection doesn’t need to be perfect, just reasonable. As straight as a ruler, as circular as I could draw with a compass, as spherical as a ball. [/ul] I can’t think of any natural object that I would consider a perfect circle or sphere. Maybe there’s an animal with a perfect circle for an eye socket or something? As for a straight edge, I would guess it would be some sort of crystal. Like the Blahblah Quartz usually grows to a length of 6 inches or whatever. ---
**Author:** ![Squink](https://avatars.discourse-cdn.com/v4/letter/s/b5e925/32.png) [@Squink](https://boards.straightdope.com/u/Squink)\ **Post date:** [September 1, 2006, 3:29pm UTC](https://boards.straightdope.com/t/whats-the-longest-naturally-occurring-straight-edge-circle-and-sphere/371080/2 "2006-09-01T15:29:27Z")
[They’re so smooth that the only thing rounder is a neutron star](http://www.collisiondetection.net/mt/archives/2004/04/the_smoothest_s.html). So at about 20 km diameter, the silhouette of a neutron star is the largest really, really accurate natural circle. ---
**Author:** ![Joey\_P](https://avatars.discourse-cdn.com/v4/letter/j/919ad9/32.png) [@Joey\_P](https://boards.straightdope.com/u/Joey_P)\ **Post date:** [September 1, 2006, 3:57pm UTC](https://boards.straightdope.com/t/whats-the-longest-naturally-occurring-straight-edge-circle-and-sphere/371080/3 "2006-09-01T15:57:43Z")
[QUOTE=Squink] [They’re so smooth that the only thing rounder is a neutron star](http://www.collisiondetection.net/mt/archives/2004/04/the_smoothest_s.html). So at about 20 km diameter, the silhouette of a neutron star is the largest really, really accurate natural circle. [/QUOTE] Those are handmade though. ---
**Author:** ![Squink](https://avatars.discourse-cdn.com/v4/letter/s/b5e925/32.png) [@Squink](https://boards.straightdope.com/u/Squink)\ **Post date:** [September 1, 2006, 4:19pm UTC](https://boards.straightdope.com/t/whats-the-longest-naturally-occurring-straight-edge-circle-and-sphere/371080/4 "2006-09-01T16:19:26Z")
[QUOTE=Joey P] Those are handmade though. [/QUOTE] Yeah, the ref was to the stars, which are a natural form. ---
**Author:** ![Ethilrist](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ethilrist/32/4604_2.png) [@Ethilrist](https://boards.straightdope.com/u/Ethilrist)\ **Post date:** [September 1, 2006, 4:33pm UTC](https://boards.straightdope.com/t/whats-the-longest-naturally-occurring-straight-edge-circle-and-sphere/371080/5 "2006-09-01T16:33:28Z")
[QUOTE=Squink] Yeah, the ref was to the stars, which are a natural form. [/QUOTE] Yeah, but although you could, technically, hold it in your hand without deforming _it_, that would probably be undesirable in the extreme. Killing the ref costs you serious points. ---
**Author:** ![Smeghead](https://avatars.discourse-cdn.com/v4/letter/s/f1d935/32.png) [@Smeghead](https://boards.straightdope.com/u/Smeghead)\ **Post date:** [September 1, 2006, 5:01pm UTC](https://boards.straightdope.com/t/whats-the-longest-naturally-occurring-straight-edge-circle-and-sphere/371080/6 "2006-09-01T17:01:21Z")
The earth is actually closer to a perfect sphere than your average billiard ball, even with all the mountains and oceans and whatnot. ---
**Author:** ![Peter\_Morris](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/peter_morris/32/359_2.png) [@Peter\_Morris](https://boards.straightdope.com/u/Peter_Morris)\ **Post date:** [September 1, 2006, 5:11pm UTC](https://boards.straightdope.com/t/whats-the-longest-naturally-occurring-straight-edge-circle-and-sphere/371080/7 "2006-09-01T17:11:30Z")
[QUOTE=Squink] So at about 20 km diameter, the silhouette of a neutron star is the largest really, really accurate natural circle. [/QUOTE] But is it a perfect sphere though? Most bodies in space are oblate spheroids, ie wider at the equator and flatter at the poles. Are neutron stars an exception? ---
**Author:** ![Schnitte](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/schnitte/32/9033_2.png) [@Schnitte](https://boards.straightdope.com/u/Schnitte)\ **Post date:** [September 1, 2006, 6:21pm UTC](https://boards.straightdope.com/t/whats-the-longest-naturally-occurring-straight-edge-circle-and-sphere/371080/8 "2006-09-01T18:21:48Z")
Neutron stars are objects of extremely high density (10[sup]12[/sup] kilograms per cubic centimeter, according to [Wikipedia](http://en.wikipedia.org/wiki/Neutron_star) - they contain several solar masses with a diameter of about 20 kilometers), according to and extremely high gravitational forces, which cause the star to tend to the form of a sphere. In the case of the Earth, the oblate form is caused by centrifugal forces at the Equator, but those are too weak to match the much stronger gravitation in a neutron star. ---
**Author:** ![Schnitte](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/schnitte/32/9033_2.png) [@Schnitte](https://boards.straightdope.com/u/Schnitte)\ **Post date:** [September 1, 2006, 6:24pm UTC](https://boards.straightdope.com/t/whats-the-longest-naturally-occurring-straight-edge-circle-and-sphere/371080/9 "2006-09-01T18:24:23Z")
My last post was messed up. Here is how it was intended to read: Neutron stars are objects of extremely high density (in the order of 10[sup]12[/sup] kilograms per cubic centimeter, according to [Wikipedia](http://en.wikipedia.org/wiki/Neutron_star) - they contain several solar masses with a diameter of about 20 kilometers), and extremely high gravitational forces, which cause the star to tend to the form of a sphere. In the case of the Earth, the oblate form is caused by centrifugal forces at the Equator, but those are too weak to match the much stronger gravitation in a neutron star. ---
**Author:** ![flex727](https://avatars.discourse-cdn.com/v4/letter/f/258eb7/32.png) [@flex727](https://boards.straightdope.com/u/flex727)\ **Post date:** [September 1, 2006, 6:34pm UTC](https://boards.straightdope.com/t/whats-the-longest-naturally-occurring-straight-edge-circle-and-sphere/371080/10 "2006-09-01T18:34:23Z")
[QUOTE=Ethilrist] Yeah, but although you could, technically, hold it in your hand without deforming _it_, that would probably be undesirable in the extreme. Killing the ref costs you serious points. [/QUOTE] The OP said _durable_, and merely gave an example of what might be durable. A neutron star is quite durable by any definition. ---
**Author:** ![flex727](https://avatars.discourse-cdn.com/v4/letter/f/258eb7/32.png) [@flex727](https://boards.straightdope.com/u/flex727)\ **Post date:** [September 1, 2006, 6:36pm UTC](https://boards.straightdope.com/t/whats-the-longest-naturally-occurring-straight-edge-circle-and-sphere/371080/11 "2006-09-01T18:36:18Z")
[QUOTE=Peter Morris] But is it a perfect sphere though? Most bodies in space are oblate spheroids, ie wider at the equator and flatter at the poles. Are neutron stars an exception? [/QUOTE] Take the cross-section through the equator, rather than the pole. ---
**Author:** ![GargoyleWB](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gargoylewb/32/199_2.png) [@GargoyleWB](https://boards.straightdope.com/u/GargoyleWB)\ **Post date:** [September 1, 2006, 6:43pm UTC](https://boards.straightdope.com/t/whats-the-longest-naturally-occurring-straight-edge-circle-and-sphere/371080/12 "2006-09-01T18:43:33Z")
Now for straight lines…this could get trickier. I vote for the rays of impact craters, like on the earth’s moon. Nice, long, straight, and pretty. And the squarest object in nature is, of course, Regis Philbin. ---
**Author:** ![Kidney](https://avatars.discourse-cdn.com/v4/letter/k/34f0e0/32.png) [@Kidney](https://boards.straightdope.com/u/Kidney)\ **Post date:** [September 1, 2006, 6:57pm UTC](https://boards.straightdope.com/t/whats-the-longest-naturally-occurring-straight-edge-circle-and-sphere/371080/13 "2006-09-01T18:57:51Z")
I was wondering more about things we might find a little closer to home. So one more rule is that it has to be found on Earth. ---
**Author:** ![TJdude825](https://avatars.discourse-cdn.com/v4/letter/t/dec6dc/32.png) [@TJdude825](https://boards.straightdope.com/u/TJdude825)\ **Post date:** [September 1, 2006, 7:00pm UTC](https://boards.straightdope.com/t/whats-the-longest-naturally-occurring-straight-edge-circle-and-sphere/371080/14 "2006-09-01T19:00:00Z")
What about a string with a weight hanging on the end? That’s straight, but I don’t know if it counts as natural. ---
**Author:** ![jjimm](https://avatars.discourse-cdn.com/v4/letter/j/ba8739/32.png) [@jjimm](https://boards.straightdope.com/u/jjimm)\ **Post date:** [September 1, 2006, 7:04pm UTC](https://boards.straightdope.com/t/whats-the-longest-naturally-occurring-straight-edge-circle-and-sphere/371080/15 "2006-09-01T19:04:11Z")
How about the basalt crystals at the [Giant’s Causeway](http://www.ivanweb.net/images/Mondo/Irlanda/Giants%20Causeway,06.jpg)? ---
**Author:** ![mittu](https://avatars.discourse-cdn.com/v4/letter/m/ecd19e/32.png) [@mittu](https://boards.straightdope.com/u/mittu)\ **Post date:** [September 1, 2006, 7:10pm UTC](https://boards.straightdope.com/t/whats-the-longest-naturally-occurring-straight-edge-circle-and-sphere/371080/16 "2006-09-01T19:10:19Z")
Is an atomic nucleus round? According to Wiki the neutrons and protons are held together by a nuclear force far stronger than gravity. ---
**Author:** ![Key\_Lime\_Guy](https://avatars.discourse-cdn.com/v4/letter/k/48db29/32.png) [@Key\_Lime\_Guy](https://boards.straightdope.com/u/Key_Lime_Guy)\ **Post date:** [September 1, 2006, 7:18pm UTC](https://boards.straightdope.com/t/whats-the-longest-naturally-occurring-straight-edge-circle-and-sphere/371080/17 "2006-09-01T19:18:24Z")
A pebble dropped in a still pond produces a perfect circle. Some of the American transcendalists were stimulated by that, I think. ---
**Author:** ![Peter\_Morris](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/peter_morris/32/359_2.png) [@Peter\_Morris](https://boards.straightdope.com/u/Peter_Morris)\ **Post date:** [September 1, 2006, 7:41pm UTC](https://boards.straightdope.com/t/whats-the-longest-naturally-occurring-straight-edge-circle-and-sphere/371080/18 "2006-09-01T19:41:09Z")
ThaNKS FOR THE INFO, \*\*Schnitte \*\* ---
**Author:** ![Peter\_Morris](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/peter_morris/32/359_2.png) [@Peter\_Morris](https://boards.straightdope.com/u/Peter_Morris)\ **Post date:** [September 1, 2006, 7:42pm UTC](https://boards.straightdope.com/t/whats-the-longest-naturally-occurring-straight-edge-circle-and-sphere/371080/19 "2006-09-01T19:42:17Z")
[QUOTE=Key Lime Guy] A pebble dropped in a still pond produces a perfect circle. . [/QUOTE] But not a durable one, though. ---
**Author:** ![KP](https://avatars.discourse-cdn.com/v4/letter/k/a9adbd/32.png) [@KP](https://boards.straightdope.com/u/KP)\ **Post date:** [September 1, 2006, 8:14pm UTC](https://boards.straightdope.com/t/whats-the-longest-naturally-occurring-straight-edge-circle-and-sphere/371080/20 "2006-09-01T20:14:19Z")
[QUOTE=mittu] Is an atomic nucleus round? According to Wiki the neutrons and protons are held together by a nuclear force far stronger than gravity. [/QUOTE] The nuclei of unranium and transuranics are classically described as (American) football shaped, so certainly _all_ nuclei are perfectly round. I’m not sure if _any_ are, but that probably doesn’t meet the OPs criteria, because the ‘surface’ of a nucleus is a problematic construct, largely a matter of definition. Besides, it’s pretty rare for an atomic nucleus to qualify as the largest anything. [Next page](https://boards.straightdope.com/t/whats-the-longest-naturally-occurring-straight-edge-circle-and-sphere/371080.md?page=2)