What happends when the semi major axis is longer?

Since this is not my area of expertise, I searched Google under the key words "semi major axis length" to get these possible sources:

http://en.wikipedia.org/wiki/Semi-major_axis
http://en.wikipedia.org/wiki/Ellipse
http://www.daviddarling.info/encyclopedia/S/semimajor.html

It would be helpful if you indicated what type of ellipse you are exploring (e.g., geometry, astronomy).

I hope this helps. Thanks for asking.