The subject of myths across the world, the physical manifestation of an ancient deity, the cause of lupine transformations, the location of alien (or pink woollen mouse) colonies, a mysterious power that affects women’s monthlies… The Moon is a source of wonder and mystery to many, but it’s also really interesting scientifically. That’s right, it’s time for some science that you probably all learned in primary school.
Actual image of the Moon
The Moon has a place in even the earliest stories that humans told. It is often associated with a deity, such as the Maya moon goddess, the Inuit god Igaluk, the Chinese goddess Chang’e, a whole host of Egyptian gods, the Roman goddess Luna and her Greek counterpart Selene. Even today, the names Luna and Selene are still associated with the Moon.
So what’s the Moons actual name? (In English at least, let’s not veer off track with Lune, Mond, Marama etc.)
To put it simply; ‘the Moon’. The name is derived from ancient Germanic roots. However, given the wonders of English, adjectives describing the Moon come from Latin and Greek origins, hence ‘lunar lander’, ‘selenography’ and so on. In all fairness ‘lunar lander’ sounds way better than ‘moonar lander’
Then why do other planets have moons?
They don’t! Did I just blow your mind? We often misuse the word ‘moon’ to describe the natural satellites of other planets. Confusing right? Well that’s what happens when something is discovered and studied over thousands of years, spanning cultures and languages.
So, while the Earth’s ‘moon’ is called ‘Moon’ ‘the Moon’ or sometimes ‘Luna’, all others are commonly mislabelled as ‘moons’ but should be described as natural satellites. The natural satellites of other planets are named other stuff like Deimos, Phobos, Europa, Io, Ganymede, Callisto etc. Does that make sense?
Calling natural satellites of other planets ‘moons’ is kind of like calling all countries englands and then calling England ‘The England’
But it’s ok to call them moons, no one really minds and even scientists do it.
Coincidentally, what happened with the word ‘moon’ also happened with ‘sun’. ‘Sun’ is the name of the star at the centre of the Solar system, Solar being the name of the planetary system Earth is in, Sol being the latin name of Sun (once again, sun derived from ancient germanic roots and its adjective, solar, from latin). ‘Suns’ in other systems are in fact stars with their own names such as Proxima Centauri of the Alpha Centauri system, or Sirius A and B of the Sirius system. However, like ‘moon’, ‘sun’ is usually used to describe a star at the centre of a planetary system. Stars with no planets are just stars.
This problem stems from early civilisations believing the Moon and the Sun were unique objects in the sky and different to all the other celestial bodies because they appear as similar sizes, despite the Sun’s diameter being 400 times larger than the Moon’s. The fact that the Sun is also 400 times further away from Earth than the Moon means they appear to us to be the same size.
How did Earth acquire a Moon … gah sorry, natural satellite?
Well if you read up on various mythologies, the Moon is often one of the first of two gods, Moon and Sun, and they have a lot of fun together (or not so much fun together… seriously, read about Igaluk). Or the Moon is associated with death, or a god created it because… why not? But these days, thanks to telescopes and sciencey thinking, it’s more widely regarded that possibly 4.5 billion years ago….
A planet roughly the size of Mars (so, smaller than Earth), named Theia, crashed into a newly formed Earth (Only 50 million years old, practically a baby), causing both planets to heat up substantially and eject large amounts of their hot gooey outer layers (comprised mostly of rock). This ejected matter being so large that as it cooled, it had enough of its own gravitational field to pull itself into a sphere (as did Earth). This theory explains why the Moon is primarily made of rock, in addition to large number of other reasons that I’m not going to explain –This is a blog, not a documentary.
So probably the Moon is a little part of Earth and some other rude planet that came barging through one day.
There are some other theories that are mostly discredited, including a fast-spinning Earth fissioned (spat out, basically) part of its mantle and formed the Moon (it’s thought that Earth could not have spun fast enough for this), and Earth capturing the Moon as it flew through space like a baseball (it’s thought that no trajectory would have allowed for this ) but it’s a difficult thing to prove right or wrong.
How big is the Moon?
Pretty damn big actually, it’s about a quarter of Earths diameter and the fifth largest natural satellite in the Solar system, beaten only by three of Jupiter’s natural satellites (Ganymede, Callisto, Io) and one of Saturn’s (Titan). Which is pretty impressive considering Earth is the fifth largest planet within the system (Jupiter and Saturn being the largest of eight planets [poor Pluto] and the Sun being pretty damn large.) and there are 182 known natural satellites in the Solar system. This also means that the Moon is the 14th* largest object within the Solar system. Also, since Pluto was downgraded, the Moon is now the largest natural satellite in the Solar system in comparison to the planet it orbits. #WeStillLoveYouPluto
So why, if the Moon is so big, are the Earth and Moon not a binary planet system?
Despite the Moon being larger than Pluto (you heard it) the common centre of mass (barycentre) between Earth and the Moon is 1,700km inside Earth. (EARTH WINS!) This means that they aren’t two bodies orbiting each other, it is one body orbiting another and offsetting it a little bit.
How does the Moon affect us mere mortals?
Well, on a full Moon, men have been known to turn into beasts and something something virgins and blood… Nah just kidding. But many (silly) people attribute strange behaviour to the full moon. Known as Lunar effects, poorly cobbled together statistics will be used to claim murder rates and mental health are worsened by the different phases of the moon. This stems from the idea that if the Moons gravity can affect the ocean tides, it’s surely affecting all that water in our brains. But is it true?
Short answer: No
Long answer: Nooooooooooooooooooooooooooooooooo. The Moon has better things to be doing than messing with your head. Also, it’s gravity just isn’t strong enough to have an effect on the water inside you. Plus, think about it, if moving the water inside you just a little bit had any effect on your mental state, you wouldn’t be able to do so much as turn over in bed without having a manic episode. It’s been studied, it’s been disproven.
The Moon DOES NOT cause, or even affect, any of the following: Fertility, birth rates, blood loss during surgery, dark and satanic forces, vampire attacks, mental illness, epilepsy, lycanthropy, your psychic powers, or a bunch of other stuff. The Moon affects the tides of enormous bodies of water, if it could affect your brain, it would also affect your ponds. Have you ever seen a pond bulge? Being relatively small in size (compared to the oceans) is partly the reason that the Mediterranean sea has such a small tidal range
People still claim the moon affects crime, the stock market, politics and voter behaviour and I can’t accurately state that these things aren’t affected by the Moon because there really is a limit to just how many ridiculous studies scientists will carry out before someone comes up with yet another absurd theory.
New theory: The moon makes my cat extra evil. Disprove me science! Oh man look how simple it was to start a new lunar effect theory.
I submit this as my evidence for lunar-induced satanic-feline amplification
What the Moon is more likely to affect is our perception of things. People may stay out later on a full moon because it’s brighter at night (a waning or waxing moon is less than half as bright as a full Moon). Animals might hunt more when it’s darker due to having better cover. Fish aren’t mating more during a full moon because there’s a full moon; they’re most likely mating more due to the high tides.
Saying murder rates are higher just because there was a full Moon is basically admitting “I can’t be bothered to do the research properly so I’m going to claim it’s space magic”
What DOES the Moon do?
The Moon DOES affect Earth’s tides. The larger something is the greater it’s gravitational force. The Moon has a gravitational force, though not as strong as Earths which is why the Moon orbits the Earth and not the other way around. The Sun has an even greater gravitational force, which extends far further than the distance of Earth from the sun, this is why eight planets are held in orbit around it.
The Moon’s gravity may be weaker than Earth’s, but it’s strong enough to cause tides. An ocean bulge will form on both the side of Earth that the Moon is facing and the opposite side. This causes high tides around the bulges, and low tides where the water has been pulled away. The Sun has a similar effect on Earth’s tides, but not as strong due to its distance.
The Moon is also slowing Earths spin, which in turn is slowing the Moons orbit around the Earth. This is causing the moon to move further away by about 38mm every year and lengthening an Earth-day by 15 microseconds every year.
I’ve written this all in the absolute simplest way, but the truth is it is incredibly complicated and far more involved than I can explain. Read up on it sometime.
Why can’t you see the dark side of the Moon?
You CAN see the dark side of the Moon, almost every night that it’s not a full Moon in fact. Because the dark side is the side the Sun is not shining on. The side of the Moon you can’t see is the far side. You can’t see the Moons backside because our natural satellite is tidally locked with Earth, meaning even though it orbits, it is always facing us with the side we see every night. (although the gravitational force of Earth and the Sun cause the Moon to shift a little, so we do see a bit more than just one side)
Have I missed anything?
The shape of the Moon is always a sphere but the position of the Sun and Earth will create dark patches, causing us to see crescent moons, Solar eclipses are where the Moon blocks the Sun from Earth (almost perfectly due to the 400 times thing), Lunar eclipses are where the earth blocks the Moon from the sun, Neil Armstrong was the first man to walk on it etc. etc. you should all know this and this blog is too long already.
*1. Sun, 2. Jupiter, 3. Saturn, 4. Uranus (hah), 5. Neptune, 6. Earth (but fifthth in planets), 7. Venus, 8. Mars, 9. Ganymede (Moon of Jupiter), 10. Titan (Moon of Saturn), 11. Mercury, 12. Callisto (Moon of Jupiter), 13. Io (Moon of Jupiter), 14. Moon (Moon of Earth)
Here’s some stuff read for this (Yes there’s a lot of Wikipedia but it’s not like this is a dissertation):
By Abigail Palmer