Planet
Atmospheric
composition
I
0
(eV)
Mercury
98% He
2% H
2
38.59
Venus
96.5%
CO
2
3.5% N
2
102.24
Earth
78.1%
N
2
20.9%
O
2
1% Ar
102.48
Mars
95.3% CO
2
2.7% N
2
2% Ar
103.25
Jupiter, Saturn Uranus, Neptune
89% H
2
11% He
24.43
Table 1:
Mean excitation energies of the atmospheres of the solar planets
