Moons
Over 150 moons populate our solar
system. The majority of moons orbit the gas giants. 13 around Neptune,
48 around Saturn and a staggering 62 orbit Jupiter. Earth has only one
moon. But what an amazing moon it is. It’s certainly not the largest
moon in our solar system (Saturn’s Titan is 2x the size of our Moon),
but it is the largest moon in relation to the host planet it orbits –
roughly a quarter its size. Because of the size relation, some
astronomers refer to the Earth/Moon system as a “double planet system”.
The Facts
The distance from the Earth to the Moon is 234,000 miles. This
distance is so great, that if you were to drive a car at 65 MPH
non-stop, it would take you approximately 4 months, 28 days and 8 hours
to reach the moon. For comparison, it would only take a person 1 day, 14
hours to drive from NY to LA at 65 MPH non-stop.
The Moon is
2,160 miles in diameter. It’s roughly 1/4 the size of the Earth. Because
the Moon is phase locked with the Earth (one side always faces the
Earth), one full day on the moon is 27.3 Earth days. Thanks to smaller
size and lower mass, it only has 1/6th the gravity of the Earth.
Because
the Moon has no atmosphere, it exists in the vacuum of space. This
means that the sky is always black because there are no molecules to
scatter the Sun’s light and that the temperature on the Moon can vary
wildly. The Moon can reach 270 degrees F in the sunlight and swing to
-240 F below at night.
Earth To The Moon – Relative
The Moon is also incredibly dusty. Layered with a dust (regolith) so
fine and sticky, the Apollo astronauts had trouble with it every time
they went to the Moon. This dust was created by micro-meteorite impacts.
The Earth doesn’t experiences these impacts because the meteorites burn
up in our thick atmosphere before reaching the ground. On the
atmosphere-less moon however, it’s like a 4 billion year old
continuously grinding gravel pit.
The Man On The Moon
The illusion of ‘The Man On The Moon’ was created from similar
impacts orders of magnitude larger. Rouge comets and asteroids smacked
into the moon. Some leaving craters 700 miles across. Lava eventually
filled the crater’s basins that these impacts created.When the
lava and magma cooled, it was darker than the surrounding material.
These basin’s are called ‘maria’ – or ‘seas’ in Latin and created the
features we recognize.
The Tides
Thanks to the gravitational pull of the Moon, it has a significant
impact on our tides. As the Moon orbits the Earth, it pulls the water
towards it. The opposite side experiences an opposite pull – similar to
that of an American football.
An extreme example of this tidal
change can be seen in Canada’s Bay of Fundy where the water level from
high tide to low tide drops an amazing 55 feet.
The Moon Is Running Away?
The Moon stabilizes the Earth’s climate by way of keeping the Earth’s
tilt stable. If our tilt wasn’t stable, the North Pole would have
extreme variations in location. Because our North Pole remains somewhat static in its location, it
allows the Earth to continuously experience the 4 seasons we know and
love. Without our Moon, or if we had a smaller moon, we would not have
our 4 seasons. Life as we know it, would be completely different.
Our
Moon is also unique in its size for its location. The Sun is 400 times
the Moon’s diameter and it just so happens that it is also 400 times as
far away. That amazing coincidence means the Sun and Moon appear to be
the same size when viewed from the surface of Earth. A total solar
eclipse, when the Moon is between the Earth and Sun, blocks the bright
light from the Sun’s photosphere allowing us to see the faint glow from
the corona, the Sun’s outer atmosphere. These types of eclipses happen
nowhere else in our solar system.
Origins Of The Moon
Supercomputer simulations show that our moon was created by a Mars sized
object impacting the Earth. The Earth absorbed much of the other
celestial object, including its heavier elements (like iron). The
lighter debris left over coalesced into the Moon. This theory is known
as the ‘Giant Impact Theory’. This impact was so massive, it started the
Earth spinning, gave us our 24 hour days and created the Moon.
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