Plasma Ion or Type I tail km

Coma 10M06 km

Dust or Type II tail 106-107 km

Figure 5.1. Structure of an active comet. The Sun is approximately in the direction opposite to the ion tail.

Nucleus 1-100 km

Figure 5.1. Structure of an active comet. The Sun is approximately in the direction opposite to the ion tail.

*

A

B

HfH & ^ * fr

c

D

Figure 5.2. Picture of the four nuclei of comets ever observed (as of 2007). A) The nucleus of comet Halley, as seen by the ESA probe Giotto in 1986 from a few thousand km (© ESA and MPAe). B) The nucleus of comet P/Borrelly observed by NASA probe Deep Space 1 in 2001 from 3400 km (© NASA). C) The nucleus of comet P/Wild 2 observed from 236 km by Stardust, the NASA probe which has returned dust samples collected during the flyby (© NASA). D) The nucleus of comet P/Temple 1 observed by NASA probe Deep Impact from 3000 km (© NASA).

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