We are seeing moon
getting brighter in the evening sky every day from the last new moon
on 20th. With each passing day more area of the moon is
illuminating and we can see lot of features on the moon. Many people have
confusion when it comes to naming the phases of the moon, so here is
a something useful to remember the names.
First, we start with couple of days
after the new moon, the phase we are seeing is crescent phase a thin
sunlit part of the moon and since the sunlit part is getting bigger
with passing days we call it waxing crescent. This is from old
English meaning something that grows, here the brighter side is
growing.
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| Waxing crescent moon. Sunlit part towards west. |
Next is First quarter, this phase
happens when the Sun, earth and the moon align in such a way that Sun and
moon are at right angles as seen from earth. We can seen this in the
evening sky, on the evening of the first quarter at sunset, we can measure the
angle between Sun at the horizon and the moon and the angle will be
90 degrees or close to 90 degrees depending on actual time of
alignment.
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| First Quarter moon. Sunlit part towards west. |
Between First quarter and Full Moon,
when more then half of the moon is lit up by sunlight we call it
gibbous phase and since the brightness is increasing its waxing
gibbous phase.
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| Waxing gibbous moon. Sunlit part towards west. |
After the first quarter comes the Full
moon phase, which we are all familiar with, in astronomy we call moon is in opposition. The moon and the sun are on the opposite sides of
the earth, if they are exactly aligned then we have a lunar eclipse.
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| Full moon |
From new moon phase the moon was in the
sky before the sunset and would set late as the days passed until
Full moon when it rises at sunset. After this the moon rises late
after sunset and the brightness starts decreasing.
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| Waning gibbous moon. Sunlit part towards east. |
Since its decreasing and more then half
is lit, but not fully lit, we call it waning gibbous phase. After
that moon reaches last quarter again attaining right angle with the
sun. This means the moon will by high in the sky at sunrise. The next
phase in waning crescent where we see thin lit surface of the moon
and finally reaching new moon phase.
From new moon to full moon, we see the
lit part is towards west and from full moon to new moon, we see the
lit part towards east, the lit part will be towards the sun.
Now I think there is no problem in
telling the phases below,
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| Last Quarter moon. Sunlit part towards east. |
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| Waning crescent moon.Sunlit part towards east. |
