When looking through my lecture notes from last term I came across many things: some very complicated equations, some parts when I had simply written stuff like "I zoned out here but something about a lava flow", but most excitingly lots of snippets of information that our lecturers mention in passing but are actually slightly mind blowing. Here, I have just noted down some of the key stuff I found that really goes against everything society teaches you (or maybe that's a little dramatic but goes against suff I thought I knew anyway). It really does show how much the Earth sciences comes up in day to day life and I hope this is as interesting to you as it is to me!
Image by Aakash Dhage via Unsplash
Myth #1: Water spirals down plugs different directions in the Northern and Southern hemispheres
It is commonly thought that water spirals down plug holes to the right in the northern hemisphere the left in the Southern hemisphere because of the Coriolis effect. The Coriolis effect is a force that deflects objects such as air (wind) or water that are not directly attached to the ground as they move over very long distances. This force arises because the earth is spinning on it's axis. It is causes many of our weather systems by deflecting the air between the poles and the equators.
However, for a fluid parcel (a bit of liquid or air) to be deflected it has to be big enough. In order for it to be big enough it needs to be over what is called the Rossby radius of deformation. If it is too small then the fluid will not feel the effects of the Earth's rotation. As plugs are so small, they well below the Rossby radius and do not feel the effects of the Coriolis force so it is in fact a myth that they change the spiral direction and you can find both clockwise and anticlockwise draining plugs in both hemispheres.
Myth #2: We should only be reducing CO2 emissions
Now don't worry, I'm not stupid, and I am very aware that we need an urgent reduction in carbon dioxide emissions in order to keep global warming due to the greenhouse effect to a minimum. This being said, when you look at the global warming potential of other gases we are releasing (all be it in smaller amounts) into the atmosphere some come way above CO2.
When talking about global warming potential, I am referring to the effect of adding 1kg of the gas into the atmosphere and how powerful of this warming effect will be. Over 20 years, methane (CH4), that is released form things such as landfill, agriculture and water treatment, will be 62 times as powerful as CO2. Even worse than this, Sulphur hexafluoride (SF6), whose release is mostly related to electrical insulation, will be 16,500 times as powerful at warming the atmosphere as Co2 will be. Reducing SF6 emissions by 1kg is as effective, from a climate perspective, as reducing CO2 emissions by 24,900kg over 100 years.
This is by no means me saying we don't need to reduced C o2 emissions, we very, very much do. I am just shedding some light on the fact that there are other gases, more potent greenhouse gases, who's emissions need to be limited as well.
All figures for this come from my lecture notes from my climate dynamics course. Similar figures can be found looking at global warming potential (GWP) figures released by the IPCC.
Myth #3: The moon is white
This one is actually quite shocking because anytime the moon is portrayed - be it in art, TV, or even images - it is white (or at least a very light shade of grey). In actual fact though, the moon is more of a brown-grey.
The moon is largely made up of two types of rock. The lunar highlands, which are on the far side of the moon that we don't see, are made of a type of rock called anorthosite that contains feldspar minerals. This rock is usually light grey in colour. The side of the moon that we see (the same side of the moon is always facing the Earth because it takes the same amount of time for it to orbit the Earth as it does to spin) is called the lunar maria and is made of a rock called basalt. Basalt is typically a dark grey/green/brown.
The moon, however, doesn't not have an atmosphere like the Earth does and for this reason it is constantly being hit by space debris such as meteorites. These impacts break up the rock on the lunar surface and cause a lot of the dust to be around. The dust then scatters the light that is reflecting off the moon and makes it look white.
Myth #4: The melting of sea ice causes sea level rise
There are different types of ice around the world. You get ice that is found in glaciers (glacial ice), ice that is on top the ground (such as ice sheets), and ice that is floating in the ocean (sea ice). When ice that is attached to land (ie on top of it) melts and the meltwater runs off into the sea then this adds to sea level rise. However, when ice that is already floating in the ocean melts and turns to water, it does not make sea level increase.
This is all down to something known as Archimedes principle. If you drop something, say a ball, into a cup of water, it will displace the water by it's own volume so the cup's water level will rise by a volume that is equal to the ball. This applies to ice as well. An ice berg will displace the sea by it's exact volume. If you then melt this ice berg, the amount of water added to the ocean is the same amount of water that was frozen in the ice berg so the volume added is just the volume that was previously being displaced. Therefore, sea level will not rise.
Myth #5: Pluto is bigger than the moon
Not sure this is actually a myth but I came across this in some reading I was doing for an essay and the information (although I am very aware that Pluto is a dwarf planet and much smaller than the other planets) still shocked me. Pluto has a diameter of around 2,400km. The moon, in contrast, has a diameter of around 3,500km. This is over 1,000km difference! I think it's a commonly not understood just how small Pluto really is.
Disclaimer: The size of Pluto is not the only reason it's now classified as a dwarf planet. To be a planet a body needs to orbit the (or a) sun, be big enough to be nearly round in shape, and have cleared it's orbital path of debris. Pluto has not cleared it's path so does not qualify to be a planet, many asteroids still fly near it's orbital path. In contrast, the larger planets have absorbed these asteroids over time.
Let's compare the size of our moon to other moons in the solar system. Saturn's most famous moon Titan has a diameter of around 5,100km. Jupiter's Galilean moons (Europa, Ganymede, Callisto, and Io) have diameters between 5,300km and 3,100km. These are pretty big and near the size of our moon. Venus' two moons, Phobos and Deimos, however, are much smaller in size at 22km and 12km in diameter respectively. So really moon sizes vary! So do the sizes of the planets! Jupiter is the biggest at a diameter of 143,000km while little Mercury has a diameter of only 4,900km!
There are many, many more examples of common misconceptions in the Earth Sciences, and I think it's really cool how I'm getting to learn all about things you hear in popular science!
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