# Spherical coordinates question **URL:** \ **Category:** Factual Questions\ **Created:** [August 14, 2002, 8:08pm UTC](https://boards.straightdope.com/t/spherical-coordinates-question/123891 "2002-08-14T20:08:07Z")\ **Posts on this page:** 9\ **Page:** 1
**Author:** ![\_xiao\_wenti](https://avatars.discourse-cdn.com/v4/letter/_/b782af/32.png) [@\_xiao\_wenti](https://boards.straightdope.com/u/_xiao_wenti)\ **Post date:** [August 14, 2002, 8:08pm UTC](https://boards.straightdope.com/t/spherical-coordinates-question/123891/1 "2002-08-14T20:08:07Z")
In spherical coordinates (r, phi, theta) what are the names for the angles? I seem to recall one being the azimuth, but which and what’s the other called? ---
**Author:** ![CalMeacham](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/calmeacham/32/35_2.png) [@CalMeacham](https://boards.straightdope.com/u/CalMeacham)\ **Post date:** [August 14, 2002, 8:39pm UTC](https://boards.straightdope.com/t/spherical-coordinates-question/123891/2 "2002-08-14T20:39:40Z")
Phi is usually the azimuthal angle Theta is the “latitudinal” angle. These are the designations I’ve seen. YMMV ---
**Author:** ![UncleBill](https://avatars.discourse-cdn.com/v4/letter/u/d26b3c/32.png) [@UncleBill](https://boards.straightdope.com/u/UncleBill)\ **Post date:** [August 14, 2002, 8:52pm UTC](https://boards.straightdope.com/t/spherical-coordinates-question/123891/3 "2002-08-14T20:52:29Z")
The angle (phi) along a given plane is the **azimuth** , as you would shoot with a compass. The next angle is the **altitude** (theta) which is the angle above or below that plane, whose horizontal component lies on the line defined by phi. The last part is **r** , the distance along that line defined by the azimuth and altitude. With this system you can define any point in three dimensional space. If I recall correctly, that is. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [August 14, 2002, 9:04pm UTC](https://boards.straightdope.com/t/spherical-coordinates-question/123891/4 "2002-08-14T21:04:43Z")
The one that goes all the way around the circle is the azimuthal angle, and the one that goes from the z axis to the point is the polar angle. Which letter you use for which depends on whether you’re a mathematician or a physicist: Physicists usually call the azimuthal angle [symbol]f[/symbol] and the polar angle [symbol]q[/symbol]; for mathematicians, it’s the reverse. ---
**Author:** ![Drogulus](https://avatars.discourse-cdn.com/v4/letter/d/e9c0ed/32.png) [@Drogulus](https://boards.straightdope.com/u/Drogulus)\ **Post date:** [August 14, 2002, 9:06pm UTC](https://boards.straightdope.com/t/spherical-coordinates-question/123891/5 "2002-08-14T21:06:00Z")
> [@](#): > > \*Originally posted by CalMeacham \* > \*\*Theta is the “latitudinal” angle. \*\* Yes, but in scientific usage it’s usually measured from one of the poles (the other pole being at theta = 180 degrees), rather than from the equator (with the poles being at theta = plus or minus 90 degrees, as in geographical latitude). ---
**Author:** ![UncleBill](https://avatars.discourse-cdn.com/v4/letter/u/d26b3c/32.png) [@UncleBill](https://boards.straightdope.com/u/UncleBill)\ **Post date:** [August 14, 2002, 9:10pm UTC](https://boards.straightdope.com/t/spherical-coordinates-question/123891/6 "2002-08-14T21:10:29Z")
I was thinking of Spherical Polar Coordinates. [Cite](http://www.chembio.uoguelph.ca/educmat/chm386/rudiment/mathbas/spherpol.htm) ---
**Author:** ![Podkayne](https://avatars.discourse-cdn.com/v4/letter/p/edb3f5/32.png) [@Podkayne](https://boards.straightdope.com/u/Podkayne)\ **Post date:** [August 14, 2002, 9:16pm UTC](https://boards.straightdope.com/t/spherical-coordinates-question/123891/7 "2002-08-14T21:16:29Z")
Theta can also be the elevation angle–in astronomy, anyway. ---
**Author:** ![sailor](https://avatars.discourse-cdn.com/v4/letter/s/a587f6/32.png) [@sailor](https://boards.straightdope.com/u/sailor)\ **Post date:** [August 14, 2002, 9:45pm UTC](https://boards.straightdope.com/t/spherical-coordinates-question/123891/8 "2002-08-14T21:45:05Z")
In celestial navigation we have Azimuth Zn (0 to 360 measured from N) and Altitude H (0 to 90 measured from the horizon). We do not measure and we are not concerned with the distance to the body, r. ---
**Author:** ![Shade](https://avatars.discourse-cdn.com/v4/letter/s/2bfe46/32.png) [@Shade](https://boards.straightdope.com/u/Shade)\ **Post date:** [August 14, 2002, 10:56pm UTC](https://boards.straightdope.com/t/spherical-coordinates-question/123891/9 "2002-08-14T22:56:06Z")
I always call azimuthal ‘round’ and polar ‘down,’ and remember phi and theta by remembering that theta also is ‘round’ in circular polars. But that only works for mathematicians, as Chronos said.