# Do comet orbits lie in the same plane as the other planets?

Two typical comets that I know are Donati's and Halley's. So comets also have orbits, but are their orbits on the same plane (such as the ecliptic) as the other planets?

Those two comets happen to have large orbital inclinations to the Ecliptic: 117$^\circ$ for C/1858 L1 (Donati) and 162$^\circ$ for 1P/Halley. Long-period comet orbits are oriented essentially at random, suggesting that they originate in the Oort cloud, a sphere several thousand AU from the Sun. Many short-period comet orbits are inclined only a few degrees to the Ecliptic, suggesting origins in the scattered disc, a torus several tens to a few hundred AU from the Sun.

• The fact that short-period comets tend to have small inclinations (and orbits that are prograde like planets and asteroids) is taken as evidence that they originate from a flattened, rotating distribution: e.g., the Kuiper Belt. – Peter Erwin Sep 23 '16 at 21:44
• Noted. The scattered disc seems to be favored over the proper Kuiper belt. – Mike G Sep 23 '16 at 23:23
• It seems the disk isn't a torus, it's a disk. Instead, the belt is the torus: "The innermost portion of the scattered disc overlaps with a torus-shaped region of orbiting objects traditionally called the Kuiper belt…" 2nd paragraph. – uhoh Sep 24 '16 at 2:02
• "...but its outer limits reach much further away from the Sun and further above and below the ecliptic" – Mike G Sep 24 '16 at 2:26
• OK so is the disk a torus? – uhoh Sep 24 '16 at 2:31