3. In Starry Messenger (Sidereus Nuncius 1610), Galileo reported his
discoveries of four moons around Jupiter with their mean orbital radii $a$
and period $T$ given in Table 1.
(a) (5 marks) Plot log $a$ (y-axis) vs log $T$ (x-axis) and show that you can
fit a straight line to the data.
(b) (5 marks) Measure the slope of the line and compare it with the value
that you expected from Kepler's 3rd law.
(c) (5 marks) Find the mass of Jupiter from the intercept of this line with
y-axis.
Name
$a$ ($10^8$ m)
$T$ (days)
Io
4.22
1.77
Europa
6.71
3.55
Ganymede
10.7
7.16
Callisto
18.8
16.7
Table 1