The Moon - Phase 2
Hello, this is Jack at My (Overly) Epic Blog. I'm really sorry, but we still have to focus on the phases of this fellow:
Yup, it's the moon. We did the moon last week, but apparently we weren't finished.
People believe some wacky things about the moon. This is true today and it was true in ancient times. You may have heard that people go crazy when it's a full moon. Like this guy:
It must be a full moon everyday around here.
In ancient China, people thought that there were 12 different moons, one to go with each month. They also believed the moons were made of water. The moon looks more like cheese than water to me. I don't think they had cheese in ancient China.
The ancient Chinese also believed that a white rabbit lived in the moon. Here's a depiction of him:
I've noticed that the moon seems to change shape over time. We all know that the moon doesn't really change shapes. It's always a spherical shape, just like Earth. We call what we see as a change in shape as . . . drumroll, please . . . . the phases of the moon!
What we call a "month" is actually based on the different phases of the moon. In fact, this is the definition of a "month" from the dictionary:
" Month: a unit of time corresponding approximately to one cycle of the moon's phases."
From Earth, we always see the same face of the moon because the moon is rotating at the same speed as the Earth is rotating. The sun always shines on the half of the moon that we see, and the other half of the moon is always in the dark. But as the moon travels around the Earth, we only get to see part of the illuminated side. What we know as the moon's phases describes the part of the moon that is illuminated from our perspective. The shape varies from a full moon (when the Earth is between the sun and the moon) and a new moon (when the moon is between the sun and the Earth).
Sometimes, the sun, the moon, and Earth line up in such a way that one of them blocks light from the other. Whenever that happens, we call it an eclipse. During a solar eclipse, the moon moves between the Earth and the sun and blocks off all the light. Here's a diagram:
A solar eclipse can only take place at the phase of new moon, when the moon passes directly between the sun and the Earth. In that case, you'd think we'd get a solar eclipse each month, but we don't.
Why don’t we get a solar eclipse each month? It’s because the moon’s orbit around the
Earth occurs at a slightly different plane than the Earth’s orbit around the
sun. So, the moon crosses the Earth’s
orbital plane only twice per year. Most
months, the moon passes above or below the sun. Plus, like I just said, for a solar eclipse to
take place, the moon must be in the new moon phase. That’s why solar eclipses are so rare. Here's an actual picture:
During a lunar eclipse, the Earth blocks the light from the sun that normally lights up the moon.
A lunar eclipse can only occur at a full moon. We don’t get them on a monthly basis for a similar reason that we don’t get a solar eclipse every month: because the moon’s orbit around the Earth occurs at a slightly different plane than the Earth’s orbit around the sun.
When I think about the phases of the moon, it helps me to see the whole picture. Here’s a
diagram of the phases of the moon. I’ll
explain each one after we see the whole picture.
There are lots of new words to learn when describing the
phases of the moon.
I'll start with waxing and waning. Waxing is the phase when the
illumination of the moon is increasing.
The moon appears to be getting larger.
Waning is the opposite of waxing. During this phase, the illumination of the
moon is decreasing. The moon appears to
be getting smaller.
The first phase of the moon is called the new
moon. This is when the moon lies
closest to the sun in the sky as seen from Earth. We can’t see the moon at this time, except if
there’s a solar eclipse.
Crescent
moons refer to when the moon is less than half illuminated.
The waxing crescent moon is the first
sliver of the moon that we can see.
A first
quarter moon occurs when the moon is halfway illuminated. In this
phase, the right-handed side of the moon is lit up.
Gibbous
moons refer to when the moon is more than half illuminated.
A waxing gibbous occurs when the moon
is more illuminated than half, but is not yet a full moon.
A full moon means that the moon is
fully illuminated by the light of the sun.
It appears as s complete circle.
This is the only time we can see a lunar eclipse.
A waning gibbous occurs when the moon
is more illuminated than half, but is not a full moon anymore.
A last (or third) quarter moon
occurs when the moon is halfway illuminated, but now it’s the left-handed side
of the moon that is lit up.
A waning crescent occurs
when the moon is less than half illuminated.
This is the final sliver of moon we see until the moon goes totally dark
again.
The terminator is the
dividing line between illuminated and un-illuminated part of the moon.
Bye moon! See you later.
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