Question

What is the eccentricity of a planet's orbit if the focal distance is 8 and the major axis is 32?

Answer 1

Focal distance of an ellipse is given by the formula

`f = ae`

here a = length of semi major axis

e = eccentricity of the path

now here we know that

length of major axis for the path of planet is given as 32 units

so here we can say

`2a = 32 units`

`a = 16 units`

so length of semi major axis is 16 units

focal distance for the planet path is given as 8 units

now from the above formula we can write

`f = a*e`

`8 = 16*e`

`e = (8)/(16)`

`e = (1)/(2) = 0.5`

so eccentricity for the path of planet will be 0.5