On cloudless nights, you can stare up at something gleaming
down on you, lighting your path. Our calendars show its picture, telling us what
phase it will be on each day. There are many old wives' tales and stories about
the Moon. But when you look up in the sky, how much do you really know about Earth's
constant companion? Test your knowledge with this top 10 countdown on cool
facts about the Moon.
Number 10: Has
the Moon always been there? Have you ever wondered how it was formed? According
to a leading theory, the Moon was formed when a rock the size of Mars collided
with Earth 4.5 billion years ago, when the solar system was just being formed.
Number 9: Have
you ever looked up and thought, "Wow! I can see the whole Moon"? Well, you
can't. The Moon and Earth are locked in orbit. Therefore, you only see one side
of the Moon. Wondering how this is possible? A long time ago, the gravitational
effects of Earth slowed the Moon's rotation about its axis. This effect stabilized
once the Moon's rotation slowed enough to match its orbital period, the time it
takes for the Moon to go around the earth. The part of the Moon we can't see
from Earth is sometimes referred to as the "dark side of the Moon."
Number 8: Moon
trees do exist. Well, kind of. In 1971, astronaut Stuart Roosa took some tree
seeds with him aboard Apollo 14. While Alan Shepard and Edgar Mitchell walked
on the lunar surface, Roosa guarded his seeds. After Roosa returned to Earth, his
future trees were planted across the United States. To date, approximately 400 of these so-called "Moon
trees" are still thriving.
Number 7: Have
you ever wondered how the Moon got its very cratered and textured surface? It's
the result of tons of space rocks hitting the lunar surface between 4.1 and 3.8
billion years ago. These "battle scars", as they are known, have not eroded
much over billions of years for two main reasons. First, because the Moon is
not geologically active in any significant way, moonquakes and volcanoes do not
transform the landscape. Second, because there is little to the lunar atmosphere,
there is no wind or rain to cause surface erosion.
Number 6: Do you
think that the Moon is Earth's only natural satellite? If so, you may be wrong.
In 1999, astronomers discovered a 3-mile wide asteroid that may be caught in
Earth's gravitational grip. This, of course, would make the asteroid another
natural satellite of our planet. Cruinthe, as this asteroid is called, will take
770 years to complete its horseshoe-shaped orbit around Earth. But don't worry
about Cruinthe's departure before that. Scientists believe that Earth's gravity
has caught Cruithne for at least 5000 years.
Number 5: When viewed
with the naked eye, the Moon looks spherical and round. But in actuality, the Moon
is shaped like an egg with one of the small ends pointed right at you! Therefore,
the Moon's center of mass is not at the geometric center, but is instead about
1.2 miles off-center.
Number 4: The Moon
quakes! When Apollo astronauts visited the Moon, they used seismometers and
discovered that small Moon quakes originate several miles below the lunar surface.
These quakes, which are thought to be caused by the gravitational pull of the
Earth, are sometimes large enough to cause tiny fractures to appear at the lunar
surface, allowing gas to escape from the Moon's core.
Number 3: The Moon
could be considered a planet. The Moon is larger then Pluto and is 1/4 the
diameter of Earth. Many scientists refer to the Earth-Moon system as a double
planet.
Number 2: We all
know that the tides go in and out, and many are aware that this is caused by
the Moon. But have you ever wondered what actually causes this phenomenon that
helps fishermen around the globe? The Moon's gravity pulls on Earth's oceans. High
tide aligns with the Moon as Earth spins below. Another high tide occurs on the
exact opposite side of the globe because gravity pulls the Earth toward the Moon
more than it pulls water. The tug of the Moon does more than create Earth's
tides, however. The Moon is actually stealing some of Earth's rotational energy,
causing our planet to slow down by 1.5 milliseconds every century.
Number 1: Our Moon
is leaving us! The Moon is propelling itself away from our planet with the
rotational energy that it is stealing from Earth. Each year, the Moon moves
approximately 3.8 centimeters higher in orbit. When the Moon was formed, it was
only 14,000 miles from Earth. Today, it is more then 280,000 miles above us.
Our Moon is a fascinating celestial body. It has some intriguing
characteristics and does some helpful things. So, the next time you look up at
it, see the Moon for all that it is. And, of course, don't forget about the
proverbial "Man in the Moon" smiling down upon us!
CR4 Aerospace Blog
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Re: Test Your Knowledge About the Moon
