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".