Graphing Orbits

[Chezburgar7300]

Hi everybody,
I'm stressing hard because I've got an assignment due soon on orbital dynamics and I cannot for the life of me find anything on the internet to graph orbits. It doesn't need to be specific, as for this subtopic I just need to graph the effects of changing eccentricity. 
The criteria is really simple:

• Representation of a focus point (a point of any style is acceptable)
• 2D from the point of view of somebody above it, similar in style to the spoiler.
• That's it.

Even if it's just an ellipse grapher where I can input eccentricity (or even the Minor/Major axis) I will be over the moon.

If anybody could help out, I'd greatly appreciate it. 

Spoiler

Extra points: If the software can graph multiple orbits on the same picture.

Edited June 30, 2016 by Chezburgar7300

[kerbiloid]

http://astro.unl.edu/animationsLinks.html

http://astro.unl.edu/classaction/animations/renaissance/kepler.html

 

[Bill Phil]

You just use the ellipse equation... Which is based on semi-minor and semi-major axes. There is a version based on eccentricity, but it's much more complex, and I have no idea what it is.

https://www.google.com/search?q=ellipse+equation&ie=utf-8&oe=utf-8

You could use a graphing calculator like desmos to help out.

[FancyMouse]

I think this tool is better... Just get Hyperedit and you can input anything. Multiple orbits automatic. For RL planets/moons just get RSS. etc.etc.etc.