When we think about nighttime, one of the first images
that comes to mind is the large full moon shining bright in the darkness.
The Moon is Earth’s Nightlight, and by far the brightest object in the night sky,
many times brighter than even the brightest stars.
While the Moon is the luminary that lights up the night,
it's interesting and important for us to observe:
the Moon actually does not produce its own light like the Sun does.
The Sun is composed of gas and ionized atoms that are heated so much that they emit
various forms of energy, including the visible light we see on Earth.
The Moon, on the other hand, is a solid rocky body
with a cold barren surface, no atmosphere, and no liquid water.
The Moon’s surface that we can see quite well,
especially through binoculars or telescopes, is simply reflecting light from the Sun.
Similar to a mountain range off in the distance that we see,
not from light that it emits on its own, but reflecting the sunlight.
In contrast to the brightness of the Sun, the Moon is the lesser light.
But the Moon truly does rule the night.
Within the Solar System the Earth-Moon relationship is rather unique.
In comparison to the other planets and their moons, our Moon has the
largest ratio of moon-to-planet size and diameter-to-orbital distance.
What this means is that the Moon has both a larger physical size in relation to Earth
and a larger apparent visual size in our sky than any other moon-planet system.
These simple relationships provide the foundation for the Moon’s
functional and finely-tuned role as Earth’s nearest companion.
One of the most obvious roles the Moon provides is in its timekeeping status.
As the Moon orbits around the Earth it progresses through a sequence of lunar phases,
where the Moon’s appearance slowly changes by how much it's illuminated by the Sun’s light.
Beginning with the completely darkened new moon phase, this 29.5 day lunar cycle
goes through a progression from waxing crescent, to first quarter moon,
to waxing gibbous, to its maximum illuminated state at the full moon.
Then it begins to diminish into the waning gibbous,
3rd quarter moon, waning crescent and back to a darkened new moon.
For many cultures--past and present-- the lunar cycle formed an obvious
timekeeping foundation by which their calendars could be based.
In fact the words “Moon” and “Month” share etymological origins
as the 29.5 day cycle helped define the changing of months.
At a more basic level, though, the Moon’s nightly phases serve as a rhythm for the natural world.
Nocturnal behaviors of animals from insects to birds to mammals to even marine species
have been linked to the monthly cycle of the Moon.
Now the phases of the Moon are caused by
the relative positioning of the Sun, Earth, and the Moon.
As the Moon travels in its orbit it progresses from being on the
same side of Earth as the Sun, causing the new moon,
to being on the opposite side from the Sun causing the full moon phase.
While the orbits of the Moon around the Earth
and the Earth around the Sun are not exactly aligned,
there are specific points where the orbits cross.
When the Moon passes through these points in its
minimum new moon or maximum full moon phase,
Earth is treated to a stunning eclipse event.
Lunar eclipses occur only during the full moon phase,
where the Moon’s orbit crosses precisely behind the Earth passing through its shadow.
For several hours, as the Earth’s shadow covers the Moon, the nighttime side of Earth
is treated to the bright full moon turning a dark reddish-orange.
On the other hand, solar eclipses occur only during the new moon phase
when the Moon passes in a precise alignment between the Earth and the Sun.
Though the Sun is 400 times farther away than the Moon,
and is also 400 times larger than the Moon,
this exact proportion results in the Sun and Moon being the same angular size in our sky.
The size proportions along with the precise orbital alignments,
allow solar eclipses to be one of the most dramatic natural phenomena experienced.
For several hours the Moon creeps in front of the Sun, until for a few brief minutes,
the Sun’s bright surface is completely covered by the Moon.
These few dark moments within a total solar eclipse are the only moments
when it is safe to look at the Sun without specialized protection.
And, it's only during this time that you can visually see
the upper layers of the Sun’s atmosphere.
Since it requires such a precise alignment, each total solar eclipse is only visible
for a few minutes to the region the Moon’s shadow casts
as it travels across the Earth’s surface.
For those who are in this narrow strip, the encounter is a full sensory experience.
The sky darkens and stars become visible,
the temperature drops noticeably by several degrees,
and the sounds of nocturnal animal life begin.
As a timekeeping element, it is easy to see how the unique experiences
of lunar and solar eclipses could be used as markers in history.
The consistent and regular presence of the Moon’s cycle
forms the foundation for nature’s nocturnal cycles,
but includes these incredible eclipse events as a punctuation in time.
Beyond its affect on time and natural cycles, the Moon plays an absolutely vital role
for the existence and the health of life on Earth.
Both the Earth and Moon exert a gravitational force on each other.
Earth’s gravitational force is much stronger and it dominates their interaction,
which is why the Moon orbits around Earth.
However, the Moon’s gravity has a crucial impact on Earth and even in our very lives.
If you have ever been to an ocean beach or a coastline,
then you have seen the effect of the Moon’s gravity--the tides.
Even though the Moon is at a great distance from Earth, approximately 240,000 miles,
its gravitational force produces the ocean’s tides.
Each day, all around the globe, high tides and low tides
are seen all along Earth's coastlines.
This natural cycle of the ocean’s level rising and falling
produces positive benefits for life on Earth.
Every day beaches are swept across with incoming and outgoing waters.
These waters bring nutrients from farther out in the ocean for creatures that live
in the shallows or the tidal pools.
The outgoing tides can serve as a means of cleansing, refreshing the coastal regions.
They can take minerals and salts back out to the deeper waters.
The tides as a whole benefit from the impact of the circulating currents
driven by the daily cycle of the Moon's causing of these tides.
With over 70% of Earth’s surface covered by oceans,
the impact that the Moon plays directly on life cannot be underestimated.
The Moon is beautiful to observe-- a constant nightly companion.
While the Moon fulfills its role of lighting the night,
it also serves key roles in the cycles of life.
The Moon has served as a timekeeping element for both animal populations
as well as human civilizations throughout history.
Through its precise size and orbital alignments, the eclipses have punctuated history
with dramatic observational experiences.
In its formation of ocean tides, the Moon has far reaching effects
for sustaining sea life, influencing coastal conditions,
and even affecting the atmospheric conditions.
As the only body outside of Earth that man has
personally landed on, set foot on and explored,
our relationship to the Moon may be greater than any other celestial body.
Created by God, the Moon has a designed role to support the balance of life here on Earth.