The moon is a truly spectacular sight that many of us take for granted. To give our celestial neighbour its due appreciation, this Saturday, September 18th, has been declared “International Observe the Moon Night“. All across the globe events will give people a chance to view our celestial neighbour up close, and to see some of its unique mountains and craters.
Despite the Moon’s familiarity, sometimes we forget what a profound impact it has had on our planet. So, for fun, Cosmoboy has come up with a Top Ten list of ways the Moon has changed or impacted the Earth and people. If people think some important events/factors have been missed, please leave a message!
10. Lunacy, werewolves and the full moon
“Lunatic” derives directly from luna – the Moon. The idea of people showing periodic insanity depending on changes of the moon predates the 13th century (the supposed root of the word). Despite a lot of scientific studies, no credible link between the full moon and psychology and physiology has been found. Even though people joke about doing silly things on the full moon, and likely many pranks are inspired as a result, hospital emergency rooms are not inundated with howling mobs on these nights! One surprising thing — scientists take this idea really seriously! There have been a lot of studies on the “lunar effect“.
The idea of werewolves goes all the way back to Greece, and has been a staple of mythology for thousands of years. The term lycanthrope is derived from lykanthropos, or wolf-man. While the myths are full of different factors that start the shape change, the first depiction of the full moon playing a role is probably a story in Gaius Petronius‘ Satyricon (Petronius was an advisor to Nero). Today… well we wouldn’t have the Twilight saga without it!
9. Animal behaviour
While humans don’t seem to have any particular physiological or psychological link to the moon, many animals do. Corals in particular spawn around the full moon. Perhaps unsurprisingly, creatures heavily impacted by tides carry an internal “circalunar” clock. Fiddle crabs are more active in labs at low tide times. Of course moonlight also impacts behaviour: some animals need to hide better, others use moonlight to hunt more effectively. Amazingly, the African dung beetle uses the scattered light of the moon to help it walk in straight lines – does it walk around like a drunk without it?
One really strange fact: a 2007 study found that pet emergency visits do seem to increase around the full moon. I think that one really needs a follow-up! Has there been one?
8. Moon landings
Couldn’t talk about the Moon without mentioning the heroic Apollo Moon landings. And no, they weren’t a hoax. Buzz Aldrin will punch you on the nose for that one, or you can watch the Mythbusters episode about it. There’s little denying that this huge technological achievement by NASA galvanized United States for well over a decade. An entire generation grew up with the Moon landings as the benchmark of human exploration and achievement. Who can forget the “Eagle” landing, and the Moon rover bouncing around?
It’s hard to believe that in December 2012, it will be 40 years since Gene Cernan was the last person to walk on the Moon.
7. Cultural references
Moon dieties have appeared in religions all across the globe, and you kind find a list of almost 80 on wikipedia. The moon’s influence on literature and language is equally large. This eternal feature in the sky has inspired many phrases – “over the Moon”, “reach for the Moon”, “once in a blue Moon” and even the idea of the “Man in the Moon”. Once photography from the Moon became possible (Apollo missions) the “Earthrise” image it produced became a symbol of the Earth’s uniqueness.
6. Scientific progress
Our nearest celestial neighbour has been the subject of so many scientific studies it would be impossible to list them all here. So let’s focus on one – Galileo’s observations of the Moon. Prior to him turning his telescope skyward, many thought the Moon to be smooth, perhaps even polished. As soon as Galileo looked through his telescope, he could see that absolutely wasn’t true:
“A most beautiful and rapturous sight to behold … It does not possess a smoothe and polished surface but is rough and uneven and, similar to the earth itself, is everywhere full of vast protuberances, deep chasms, and sinuosities.“
For all his brilliant achievements, Galileo did make a few errors. For one, he called Kepler’s idea that the Moon causes tides “a useless fiction“…
The Moon is the most significant contributor to tides on the Earth – the Sun causes them too, but the effect is a bit under half that of the Moon. Align the Sun and Moon, then you get strong “spring” tides, have them in opposite directions and you get weak “neap” tides.
Anyone that has grown up by the sea is intimately familiar with tides. But perhaps no place is more famous for its tides than the Bay of Fundy. Enormous 40 foot tides occur on a regular basis and peaks have reached 55 feet. This happens because of the Bay’s unique geography. The amount of time it takes a water disturbance to travel all the way along the Bay is roughly the same as the time between tides. This creates what oceanographers call a “tidal resonance”. Being able to walk on the sea floor is pretty incredible.
Neolithic peoples understood the seasons. The Egyptians had a calendar based upon 4 cycles. So where do the 12 months come from? The full lunar cycle takes 29.5 days, and multiply that by 12 to give 354.4 days, which is almost exactly a year. But not quite, and it’s the “not quite” that meant people had to think about changing the length of lunar months. Make it 30 days and then you get 360 days — that’s better. But it’s clearly going to get out of sync. Handling these extra bits of time gave societies headaches for literally thousands of years.
3. Length of day
Isn’t that set by the spin of the Earth? Yes! But the Moon impacts the spin of the Earth too! Ever since the Earth-Moon system was created the Moon has actually been slowing down the spin of the Earth. It’s gravitational pull on the Earth acts like a break on the spin (or “drag”). As a byproduct of this effect the Moon has become locked with one face toward us, but the Moon does still rotate.
So how fast would the Earth be spinning if the Moon wasn’t there? Estimates suggest as fast as 8 hours a day! That would mean much faster winds as well.
2. Formation of the Moon
The best theory for the formation of the Moon is that a smaller “proto-Earth” collided with a larger object about the size of Mars to form the Earth-Moon system. In the ensuing massive collision, material was spilled out into space and our Moon then condensed out of that material over a period of hundreds of years. At the same time, the Earth acquired its spin. Amazingly, this model seems to predict the geological make-up of the Earth-Moon system very accurately.
1. Life itself?
OK, this is a long shot, but it’s a fun one. While there are many theories for how life on Earth began, one of them is that “tidal pools” allowed organic chemicals in the oceans to become concentrated into a much thicker solution. Was that concentration effect, as water is evaporated away, one of the key steps leading to the complex chemistry of life? This idea is one of the main factors in the “Rare Earth” hypothesis, that highly evolved life is very rare in the Universe because of a series of unique factors affecting the Earth. OK… the Sun does cause some tides too, but research on this idea is very active.
Who knows, maybe we owe our very existence to the Moon!