The formula to calculate the gravitational force between two objects is F_g=\frac{GM_1M_2}{r^2},F
g
​
=
r
2

GM
1
​
M
2
​

​
, where M_1M
1
​
and M_2M
2
​
are the masses of the objects, GG is the gravitational constant and rr is the distance between the objects. Solve for M_2M
2
​
in terms of F_g,F
g
​
, G,G, M_1M
1
​
and r.r.