•Use the “synodic” period of Mars to find its
“sidereal” period
–Synodic
period: Time it takes Earth to “lap” Mars as both
orbit Sun.
•This is the time between Mars “oppositions as seen
from Earth.
•780 days, or a little over 2 years
–Sidereal
period: Time it takes Mars to orbit Sun = 1 Mars Year
•1/P = 1/E – 1/S
= 1/365 days – 1/780 days =
1/687 days
•
•Collect pairs of Mars observations taken 1 Mars year
(687 days)
apart
•
•For
these pairs of observations Mars will be in the same place in its orbit
•Earth
will be in a different place – allowing triangulation