During the lecture I was asked about the axial tilt (= obliquity) of other solar system bodies.
Because I was not able to give very accurate information, I promised to find out.


Here is a summary:

The axial tilt of other planets ranges from almost 0 (Mercury) to 82 (Uranus).

The innermost planets Mercury and Venus have a relatively stable obliquity, probably
stablized by the influence of the Sun. 

Earth's obliquity would, according to simulations, change relatively rapidly without the
influence of the Moon.

The obliquities of the larger outer planets are considered relatively stable, but
Mars's obliquity is called "chaotic" and apparently can vary between 0 and 60
degrees over timescale of millions of years. Some authors have even suggested 
that variations in its obliquity have had an effect on the existence (appearance and
disappearance) of liquid water on Mars.

Please note that the orbital planes of planets do not deviate very much from the ecliptic plane
(less than 3 degrees except Mercury 7 degrees), as discussed in the lecture.
The correct term for that is "orbital inclination", even though I probably sloppily
in some occasion called the obliquity also "inclination". According to Wikipedia
this is a common misuse of the word inclination, and the less ambiguous "obliquity"
should always be used instead. I'll keep that in mind, too :)