All About Our Moon


Today, we’re going to explore the Moon. Its hostile environment, its creation, and our exploration of it in the last few decades.

We’ll also see why it’s one of a kind (at least in our solar system). The Moon is actually quite special. Today we’ll find out why.


Over 150 moons populate our solar system. The majority of moons orbit the gas giants. 13 around Neptune, 58 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

moon landingThe 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 100km/h 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 about 1 day, 14 hours to drive from Sydney to Perth at 100 km/h 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
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.

Bay Of Fundy Tide Extremes

The Moon Is Running Away?

The first person to suggest that the Moon was getting further away from the Earth was Charles Darwin’s son, George Darwin.orbit In 1878, George introduced his “fission” hypothesis of the genesis of the moon. While his fission hypothesis was proven incorrect, his extensive knowledge and analysis of tides led him to the correct conclusion that our Moon was indeed moving away from the Earth. His conclusion was not proved until 95 years later when Apollo astronauts put mirrors on the moon for researchers to bounce lasers off of. They found that the Moon was indeed moving away from the Earth at approximately 3.5 cm a year (1 1/2 inch).

Don’t fret though, after a few billion years, the Moon’s orbit will slow and stabilize – being permanently locked with the Earth’s. Though by that time, our Sun will have already turned into a red giant and baked our planet to a crisp.

Why Is Our Moon Special?

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.solar eclipse 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 Moonmoon origin

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.

Life Without The Moon?

The Moon is unique among our observed celestial bodies. There is no other satellite closer in size and composition to its host-planet (if one excludes the dwarf planet Pluto), and the Earth-moon system is the only tidally locked pair. Besides the obvious; no moonlit walks, no “Moon River” and no Apollo Moon landings, how would life without the Moon affect us here on Earth?

For starters, we’d be (mostly) without tides. The Moon’s gravity tugs on the planet, and oceans creating them. Tides are pretty important. “They helps transport heat from the equator to the poles,” says Bruce Bills, a geodynamicist at the NASA Jet Propulsion Laboratory in Pasadena, Calif. “Without the lunar tides, it’s conceivable that climate oscillations from the ice age to the interglacial would be less extreme than they are. Such glaciations caused migrations of animal and plant species that probably helped speed up speciation.”

Without the moon, the Earth would also rotate much faster, causing a more turbulent atmosphere, and thus unending gales of life-hostile, skirt-blowing winds. As the moon’s orbit slowly creeps away from the Earth at 1.5 inches per year, her gravimetric drag will eventually slow the Earth’s rotation to match the pace of the moon’s orbit. One day will be 9,600 hours long, and the moon will only be visible from one hemisphere. Of course, by then the sun should be in an expanding red-giant phase, slowly engulfing its planets. The sun’s coronal atmosphere could be creating drag against the moon, slowing it toward an eventual breakup as Earth’s gravity tears it apart. But by then, the Earth’s surface will be uninhabitable due to the scorching heat.

Recent computer simulations suggest that, without the Moon, the Earth’s axis tilt may have been very different than what it is today. This would have caused very different seasons on the Earth. The impact that this could have had on the developing biosphere ranges from moderate to catastrophic. The Moon helped to stabilize the tilt of the Earth’s rotation axis over the course of billions of years.

The Earth would be a very different place without our moon. Life as we know it on our planet may not have existed without it. Original source: Zidbits


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