In: Physics
Comet Halley has a sidereal period of 75.316 years and an eccentricity of e=9.67.
a. What is the length of its orbital semi-major axis in AU?
b. What is the closest it gets to the Sun in AU?
c. The farthest in AU ?
i. How fast (orbital speed) is it moving at perihelion in
1. AU/yr
2. Km/sec
ii. How fast is it moving at aphelion in
1. AU/yr
2. Km/sec
Kepler’s third law says that a3 ∝T2 . If we measure a in AU and T in years, then the constant of proportionality is 1, and we can write that a3= T2 . Since we are given that T = 75.316 years for Halley’s comet: a = = = = 17.83 AU
a). Hence length of orbital semi-major axis is a= 17.83 AU
b)The perihelion distance is given by: = a(1 − e) = 17.83*(1 − 0.967) = 0.588 AU
c)Similarly, the aphelion distance is given by: = a(1 + e) = 17.83*(1 + 0.967) = 35.07 AU
d) The orbital speed of the comet at Perihelion is 54km/s or 11.39 AU/yr
e) The orbital speed of the comet at the Aphelion is 0.879km/s or 0.185AU/yr