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?

Phi is usually the azimuthal angle

Theta is the “latitudinal” angle.

These are the designations I’ve seen. YMMV

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.

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.

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).

I was thinking of Spherical Polar Coordinates. Cite

Theta can also be the elevation angle–in astronomy, anyway.

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.

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.