Pandas Planets - calculate

import sys
import pandas as pd

filename = "planets.csv"
center = 'Earth'
if len(sys.argv) > 1:
    center   = sys.argv[1]
if len(sys.argv) > 2:
    filename = sys.argv[2]

df = pd.read_csv(filename)

this = df[ df['Planet name'] == center ]
print(this)
print('----')

mass = this.iloc[0]['Mass']
print(mass)
print('----')

dist = this.iloc[0]['Distance (AU)']
print(dist)
print('----')


# gravitational force is F = G * (mass1*mass2) / distance**2
G = 6
distance = abs(dist - df['Distance (AU)'])
print(distance)
print('----')

forces = df.copy()
print(forces)
print('----')


F = G * (df['Mass'] * mass) / distance**2
print(F)
print('----')

forces['F'] = F
forces.drop(columns = 'Mass', inplace=True)
forces.drop(columns = 'Distance (AU)', inplace=True)
print(forces)
print('----')

Output:

  Planet name  Distance (AU)  Mass
2       Earth            1.0   1.0
----
1.0
----
1.0
----
0      0.60
1      0.30
2      0.00
3      0.50
4      1.77
5      4.20
6      8.50
7     18.60
8     29.00
9     38.00
10    38.00
Name: Distance (AU), dtype: float64
----
   Planet name  Distance (AU)        Mass
0      Mercury           0.40    0.055000
1        Venus           0.70    0.815000
2        Earth           1.00    1.000000
3         Mars           1.50    0.107000
4        Ceres           2.77    0.000150
5      Jupiter           5.20  318.000000
6       Saturn           9.50   95.000000
7       Uranus          19.60   14.000000
8      Neptune          30.00   17.000000
9        Pluto          39.00    0.002180
10      Charon          39.00    0.000254
----
0       0.916667
1      54.333333
2            inf
3       2.568000
4       0.000287
5     108.163265
6       7.889273
7       0.242803
8       0.121284
9       0.000009
10      0.000001
dtype: float64
----
   Planet name           F
0      Mercury    0.916667
1        Venus   54.333333
2        Earth         inf
3         Mars    2.568000
4        Ceres    0.000287
5      Jupiter  108.163265
6       Saturn    7.889273
7       Uranus    0.242803
8      Neptune    0.121284
9        Pluto    0.000009
10      Charon    0.000001
----