# Thread: konexx farthest planet from the sun

1. ## conic farthest planet from the sun

Both neptune and pluto travel around the sun elliptical orbits. For neptunes orbit a=30.10 and for pluto's orbit a=39.44, where the variable a represents the planet average distance from the sun in astronomical units. The value of the variable a also corresponds to half the length of the major axis. Pluto have highly ec centric orbit with e=.249, and neptune has a nearly circular orbit with e=.009.
1. Calculate the value of c for each planets orbit. Do I just take the eccentricity of an elipse e=c/a to find the value of c?
2. Position the sun at the origin (0,0) find the coordinates of the center of neptunes orbit and the cord center of pluto's orbit . I'm stuck here not sure what to do. Does it have to do with the distance between the origin to the center of orbits ?.
3. Find equations for neptunes orbit and for pluto's orbit. I can do this once I get through steps 1 and 2
4. Graph. I can also do this.

Any confirmation, comments, or links would be greatly appreciated . Thanks Matt

2. ## Re: konexx farthest planet from the sun

yes ... $e = \frac{c}{a} \implies c = ae$

remember that the sun is located at a focus of the elliptical orbit ... and $c$ is the focal length

finally, $a^2 = b^2 + c^2$ , where $b$ is the length of the semi-minor axis