Exercise:
Given the data in the previous
exercise,
estimate the times of moonrise and moonset
at
St.Andrews on January 1st 2001.
We know that the Moon was 7
days old,
so it was 7x12.2° = 85° east of the Sun.
It
would take the Sun about 85 days to reach this point:
it would get
there on 26th March,
very close to the Spring Equinox.
So the
Moon would have been close to the celestial equator,
and it would
rise about 6 hours before it transited across the meridian,
and
set about 6 hours after.
We have already determined that
the Moon crossed the meridian at 17:57.
So it should rise at 17:57
6 hours = 11:57
and it should set at 17:57 + 6 hours =
23:57
In fact it rose at 11:56 and set at 23:06.
This approximate calculation
has shown us that, on January 1st 2001,
the Moon would be rising
about midday,
and setting again around midnight.
Back to "The Moon".