1. The problem statement, all variables and given/known data Comets move around the sun in very elliptical orbits. At its closet approach, in 1986, Comet Halley was 8.79 x 10^7 km from the sun and moving with a speed of 54.6 km/s. What was the comet's speed when it crossed Neptune's orbit in 2006? 2. Relevant equations Mv1r1=Mv2r2 3. The attempt at a solution What I did was use the equation above, and solve for v2. But it says I'm wrong. Any Suggestions???