# Graphing angles

1. Feb 19, 2016

### tony873004

I once saw a graph of angle vs time. In order to avoid a big shift in the graph when the angle crossed over from 359 degrees to 1 degree, this graph was circular, with time along the radius of the circle.

Is there a name for this type of graph?

2. Feb 19, 2016

### Staff: Mentor

Do you mean something like this?
https://en.wikipedia.org/wiki/Polar_coordinate_system

3. Feb 19, 2016

### tony873004

Yes, except the 3 and 4 in that graph represent the magnitude of the vector. In the graph I'm think of (sorry, can't find a link to it at the moment), the 3 and 4 would represent time. The angle would change over time, so the green and blue lines would not be straight lines, and 1 standard deviation would be shaded around the line.

4. Feb 19, 2016

### Staff: Mentor

I meant, e.g. the graph of the Archimedean spiral on that Wiki-page. Polar coordinates is the closest I know to describe what you could have meant. Sorry, if it doesn't help.

5. Feb 19, 2016

### tony873004

Thanks, Archimedean spiral looks like the term I was searching for.

6. Feb 19, 2016

### Staff: Mentor

Well, it is a special case of your graph, with constant derivative. I don't know if there is some name for the general case.

7. Feb 19, 2016

### tony873004

Thanks, I noticed that after I posted. Archimedean spiral is just the data plotted in the type of graph I was describing.
The reason I'm asking is because I want to make such a graph of orbital elements vs. time, and if there is a convention that is commonly used I want to use that.
For example, would time run from the center to the circumference (that would be my guess), or from the circumference to the center? Is 0 degrees the along the +x axis? I'm also guessing yes. And if there is no convention, then I get to do it my way!

8. Feb 19, 2016

### Staff: Mentor

There are probably thousands of types of graphs out there. The 'right' choice depends only on which information has to be in it and then minimizing on how long it takes to read the information it provides. Whether the time starts or ends in the origin will likely depend on whether your data provide a starting or an ending point of time. Time might as well be along a radius or a varying radius like during the drawing of a spiral.
I guess you would have better chances to get a satisfying answer if you show us an example of how you would draw it and then read the feedbacks. (Sorry if I sounded strange, I'm lacking some English vocabulary.)

9. Feb 20, 2016

### Staff: Mentor

Orbital elements can have other critical points if the orbit changes over time.

Seeing such a plot, I would expect time to increase with increasing radius, and having zero angle to the right is probably a good choice as well.