While studying about planetary orbits in class I stumbled upon a few interesting facts about some of the planets in our solar system and how they move.
1. Retrograde Rotation:
In class we were talking about the retrograde motion exhibited by planets, which made it appear as if the planet would slow down in orbit and reverse direction. while researching this topic I came across another type of retrograde motion, retrograde rotation. Although the majority of planets in our solar system rotate clockwise both about the sun and their axis, the planets Venus and Uranus rotate about their axes in a clockwise fashion. This is just a curious phenomenon which is not yet fully understood. However, it is thought that these planets may have incurred a large impact in the past, or may simply be due to some conservation of angular momentum with its formation state.2. eccentricity
In our classical mechanics class we derived the equation for planetary motion about the sun. We derived an equation which returned a radial distance from the sun given the value of the angle, ø, that the planet made with the sun, somewhere between 0 and 2π, with 0->2π expressing a full orbit. this equation however also stated that the planets follow an elliptical path governed by a value known as the eccentricity. So I was curious and looked up the different eccentricity values of the planets around us. Note the planet venus who's eccentricity is so small that it has the most circular of all of the orbits. Also note planet mercury, having a large eccentricity giving it the most elliptical orbit.
Mercury: 0.205
Venus: 0.007
Earth: 0.017
Mars: 0.094
Jupiter: 0.049
Saturn: 0.057
Uranus: 0.046
Neptune: 0.011
also the equation for planetary motion about the sun is as follows:
r(ø) = c / (1+Ωcos(ø)), c = L^2/ (G * m_1^2 * m_2^ * µ)
m_1 = planet mass
m_2 = solar mass
L = angular momentum of the planet
Ω = eccentricity
µ = (m_1 * m_2 )/(m_1 + m_2)
G is the universal gravitational constant
Interesting
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