Overview

Earth's Moon is the brightest and largest object in our night sky. The Moon makes Earth
a more livable planet by moderating our home planet's wobble on its axis, leading to a
relatively stable climate. It also causes tides, creating a rhythm that has guided humans
for thousands of years. The Moon was likely formed after a Mars-sized body collided
with Earth several billion years ago. Earth's only natural satellite is simply called "the
Moon" because people didn't know other moons existed until Galileo Galilei discovered
four moons orbiting Jupiter in 1610. In Latin, the Moon was called Luna, which is the
main adjective for all things Moon-related: lunar.

Features on the moon's surface include:

• Craters
• Maria
• Highlands

MOON CRATERS

Are bowl-shaped landforms created by two processes:

volcanism and cratering. There are hundreds of
thousands of moon craters ranging from less than a
mile across to giant basins called mare, which were
once thought to be seas.

TYCHO CRATERS

Is one of the most prominent craters on the Moon. It

appears as a bright spot in the southern highlands with
rays of bright material that stretch across much of the
nearside. Tycho's prominence is not due to it’s size.
 MARIA

Galileo called maria (MAH ree uh), the Latin word for
"seas”, hence the name mare.

•The maria are large, dark, basaltic plains on the

Moon's surface. They are formed by ancient volcanic
activity, where lava flows filled large impact basins. The
dark color of the maria is due to the presence of iron-
rich minerals in the basaltic rocks.

•The Maria have few craters compared to surrounding

areas.

• Some well-known maria include Mare Imbrium (Sea of Rains),Mare Tranquillitatis (Sea
of Tranquility) ,Mare Crisium (Sea of Crises)and Mare Serenitatis (Sea of Serenity).

HIGHLANDS

• The highlands have a light color compared to the dark

basaltic plains of the maria. This light color is a result of the
high content of anorthitic plagioclase, a type of feldspar
mineral, and the low abundance of iron and titanium oxide
minerals in the highland rocks.

• These highlands are older than the maria and are thought to
be the original crust of the moon.

• The highlands contain mountains, valleys, and rugged

terrains. the lighter, heavily cratered regions of the Moon,
which are generally several kilometers higher than the maria.
8 Primary Phases of the Moon

THE NEW MOON

The first phase for us to consider is the 'new moon'. At New

Moon, the Moon appears to us on Earth completely dark and
unilluminated because its unlit side is facing our planet.
Strangely enough, this is when the Moon's illuminated side
is not visible from Earth at all, because the Moon is sitting
between the Earth and the Sun. So a new moon is actually
invisible to us. Occasionally if the alignment of the Sun, Moon
and Earth is just right, then a total eclipse of the Sun by the
Moon is possible. A total solar eclipse can only occur during
the new moon phase of the lunar cycle.

WAXING CRESCENT
The second phase of the Moon is called the 'waxing
crescent'. Waxing in this instance means gradually
increasing in magnitude or extent, which sums up nicely
what the Moon is doing. During this period the Moon is
getting brighter and also more of it is illuminated and visible,
going from what we call in our house the 'thin Cheshire Cat'
smile from Alice's Adventures in Wonderland to the next
phase, the first quarter.

THE FIRST QUARTER

The 'first quarter' initially seems like a misnomer as half of
the moon's disc is visible from Earth due to the light from the
Sun. This occurs approximately one week after the new
moon. The reason this phase is called the First Quarter is
that the Moon has completed 1/4 of its orbit around the
Earth. This phase of the Moon is also known as a Half Moon
because only half of the Moon is visible. Because the Earth,
Moon, & Sun are at a right angle instead of a straight line,
and the Moon and Sun pull in different directions, the First
Quarter phase has the smallest effect on the ocean's tides.
THE WAXING GIBBOUS
The next phase is called the 'waxing gibbous'. The term
gibbous comes from the Latin word Gibbus, meaning
humped or hunched, and went on to mean something
rounded or protuberant. This aptly describes this phase of
the Moon, where more than half of its sunlit side can be
seen. this phase is called Waxing Gibbous because the
surface area of the Moon that you see is increasing and the
shape of the lit-up part of the Moon looks like a hump-back.
This phase is one step in the cycle away from the Full Moon
phase, where the Sun, Earth, and Moon are in a straight line.

THE FULL MOON

With the moon waxing with time we eventually get to the 'full
moon' approximately two weeks after the new moon. This is
the Moon at its most striking with its daylight side fully visible
from Earth. The new moon now sits on the opposite side of
the Earth from the Sun in a position called 'opposition',
meaning it is on the other side of the sky. A total eclipse of
the moon can only occur in this phase. At this point in the
cycle, the Earth, Moon, and Sun are in a straight line in
relation to each oth-er, causing the surface of the Moon to
be fully illuminated from our view on Earth. This is why it's
also called a Full Moon because all of the Moon's surface is visible.

THE WANING GIBBOUS

Having reached maximum brightness, the only way from
here is a diminishing moon, which is termed 'waning'. This
comes from the old English word wonian, which means to
lessen or diminish The term waning means decreasing, and
the term gibbous means "humped-back."This phase is
called the 'waning gibbous'. It looks similar to the waxing
gibbous with more than half of the daylight side of the Moon
visible, but the luminated visible area of the Moon is
diminishing as the cycle goes on. Therefore, this phase is
called Waning Gibbous because the surface area of the
Moon that you see is decreasing and the shape of the lit-up part of the Moon looks like a
hump-back.

THE LAST QUARTER

The 'last quarter' is the next phase of the cycle when, as with
the first quarter, half of the Moon's lit disc is visible from
Earth. Once again, we are at a point where the moon
appears to split in half as a last quarter moon. At this phase
of the moon, it has cycled through 3/4 of its life. But it has
reversed which side is lit by the sun. And instead of it
progressively appearing fuller, we begin to see less of the
moon. It visibly appears to be shrinking as it approaches
back to a new moon.

THE WANING CRESCENT

The final phase is called the 'waning crescent and it occurs
when a crescent moon is visible but it is waning and growing
smaller as the cycle proceeds. A couple of days after, you
get a waning crescent moon. We start to see less and less
of the moon as the moon orbits past the 270° cycle. When
the moon has completed its full 360° orbit around the Earth,
we are back to the first phase. The new moon phase marks
the starting point of a brand-new cycle of the moon.
Sometimes people also like to talk of the 'oldmoon', a very
thin crescent that occurs just before the Moon is invisible
again at the start of the cycle, the new moon.
At all times, the sun illuminates half of the moon. This is the same as Earth because half
the Earth is lit during the day and half of it is in darkness at night.

But it’s because of our perspective and where we are on Earth, how we see the 8 major
phases of the moon. The moon looks bright from Earth because it’s in full sunlight.

Because the moon is a sphere and orbits the Earth, we see it differently based on time.
In the diagram, the phase of the moon is based on the position of the moon and how
much sunlight is shining from the right side.

Overall, it’s the “day-night line” that we see from Earth that represents the 8 phases of the
moon. And we determine the phases of the moon by how much the moon is lit up by the
sun.