Some of the most common mistakes/difficulties

The perspective that the Earth precesses 360 degrees to the central
Sun as a component of its orbital motion thereby obviating the need
for axial precession as it is currently understood is not only
supported by graphics but also observational evidence of another
planet,in this case Uranus.

It is a 100% certainty that the Earth's polar coordinates turn in a
circle to the central Sun as representative of all locations on Earth
hence the graphic of Earth matches the observations of Uranus as it
moves along its orbital circuit -

http://en.wikipedia.org/wiki/File:Earth_precession.svg

http://www.daviddarling.info/images/...gs_changes.jpg

In effectively looking at the interaction of daily and orbital motions
locally it becomes fairly easy to assign cause with effect such as why
there is a polar day/night cycle as the polar coordinates turn towards
and away from the Sun or why a planet's climate is defined by the
degree of axial inclination where 0 inclination reflects an equatorial
climate and 90 degrees a polar climate,the latter view negates the
older 'no tilt/no seasons' and gets rid of precession as an axial
trait and puts it into a roughly 26 000 year orbital feature.

To achieve a local view where most researchers can operate comfortably
without constantly referring the Earth motions to external
sources,indeed they can work that way without having to know the
technical ins and outs of external cyclical references,it is crucial
to follow the development of timekeeping systems in tandem with the
specific references which comprise the connections between the raw
astronomical data and the human formatting of that data into a
convenient state.

It was nice to witness an engineering feat and the community
celebration of that achievement yesterday yet sometimes individual
astronomical works do not allow for these things as the transition
from an old to a new point of view is often awkward and
contentious.The ability of men to explore our planet centuries ago
using a watch for navigation purposes is now extended into the modern
era where spacecraft venture into the celestial arena and land on
other planets and these incredible engineering features tell you
almost nothing about astronomy other than the great cycles supply
information which humans process to the best of their ability and turn
into practical applications.