Predicting Weather By The Moon - Xavier University Libraries

Early Moon Watchers
And as Bartolomaeus Anglicus, 13 th century scholar,
observed
‘The North winde…purgeth and cleanseth raine, and driveth
away clowdes and mistes, and bringeth in cleerness and
faire weather; and againward, for the South winde is hot &
moyst, it doth the contrary deedes: for it maketh the aire
thicke and troubly, & and breedeth darknesse.’
Around 200A.D. the Greek mathematician, astronomer
and geographer Ptolemy, resident in Alexandria, reexamined
the old idea that the earth was stationary and that
everything else revolved around it. He concluded that the
idea was flawed because if true, at times the Moon would
have to appear twice as big as at other times. That it did not
was quite worrisome to Ptolemy but something, fearing
for his life he was forced to ignore, because the Christian
church needed a picture of the universe that did not conflict
with the Scriptures, leaving plenty of room outside
the sphere of stars for heaven and hell.
Ptolemy also fully described what has come to be
known as the ‘Moon illusion’, in which the Moon hanging
low over the horizon looks much bigger than when it is
high in the sky. Actually it is the same size. This is not an
optical effect but a psychological one.
The Mayan, the Chinese and the Egyptians, did seem
to know about the longer Moon cycles and passed the
knowledge on. In this way they were able to plot and plan
over several lifetimes for solstices, equinoxes and
eclipses. For instance, it was known that eclipses repeat
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