# astronomy/physics

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Mercury has a semi-major axis of 0.367AU and an eccentricity of e=0.206. Calculate its distance to the Sun at perihelion. Remember to use units of AU in your answer.

• astronomy/physics -

let c be the distance from the center to the focus
let a be the semi-major axis

e = c/a
c = e*a = .206*.367 = .0756

distance at perihelion = a-c = .367 - .0756 = 0.291

oh, yeah. AU (duh)

• astronomy/physics -

semi-major axis = a = 0.367 au
closest distance = (1-e)*a = 0.794 a
= 0.291 au

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