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There will be an occultation of Saturn by the Moon on the morning of the 22nd of February visible from New Zealand and most of Australia.
A Blue Moon
By popular definition, the Blue Moon is the second full moon to occur in any calendar month. The term "Blue Moon" has been used
in the English language for over 400 years but there seems to be no reference as to why the second full moon should be referred to as blue.
It certainly does not turn blue in colour. An average month is around 30.5 days and the average interval between full moons is 29.5 days so
it makes the incidence of two full moons in the one calendar month a rarity. Every century there is an average of 41 months that contain two
full moons which makes an average of two-and-a-half years between Blue Moons. So we have the term "Once in a Blue Moon" used today
to indicate that something occurs "not very often". At the other extreme February is the only month that can miss out on having a
full moon and this only occurs four or five times every century.
The Sun is 400 times larger than the Moon but because it lies 400 times further away they appear to be the same angular size in the sky
(about 1/2degree), so that it is possible for the Moon to totally cover the Sun's disc. If the Sun, Moon and Earth lie directly in a
straight line then a total or annular eclipse will occur. If the Moon's orbit around the Earth was to lie in the same plane as Earth's orbit
around the Sun there would be a solar eclipse every new moon and a total lunar eclipse every full moon. The two planes are however inclined
at an angle of 5 degrees, intersecting only at the nodes of the Moon's orbit and this is when the eclipses can occur.
WARNING:- Under no circumstances should you try to observe the Sun
without the correct solar filters... or serious eye damage will occur.
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