Table 1. Typical values for the neutral gas mass M and magnetic field B at different objects.

Global interactions

Mercury

195

6.6 10³

N = 4.4 10⁴ O/cm⁻³ (Wurz and Lammer, 2003)

Venus

10

4.8 10²⁰

Earth

3.08 104

5.3 10¹⁸

Moon

7

2.7 10⁴

Mars

3.4

2.5 10¹⁶

Ancient Mars

60

2.0 10¹⁸

0.5 bar surface pressure

Phobos

3.4

2.7 10³

Q = 10²³ s⁻¹ (upper limit, Ip and Banaszkiewicz, 1990)

Jupiter

4.25 10⁵

2.6 10²⁰

M from 1 bar level

Ganymede

770

1.8 10⁵

Callisto

23

1.2 10⁷

Saturn

2.0 10⁴

4.3 10²⁰

M from 1 bar level

Titan

5

9.0 10¹⁸

Uranus

2.3 10⁴

9.5 10¹⁹

M from 1 bar level

Neptune

1.4 10⁴

6.9 10¹⁹

M from 1 bar level

Comet Hale-Bopp

7

2.7 10¹¹

Q = 1.0 10³¹ s⁻¹ (Biver et al., 1997)

Comet 26P/Grigg-Skjellerup

7

1.3 10⁸

Q = 7.5 10²⁷ s⁻¹ (Johnstone et al., 1993)

Small scale interactions

Lunar magnetic anomalies

300

2.7 10⁴

M same as for the Moon

Mars magnetic anomalies

1500

2.5 10¹⁶

M same as for Mars