The year-long activity of posting a weekly curiosity box is slowly nearing its end. One year ago, I decided to share topics that got me curious every week. With 3 more to go, this week, I explore 

1 – Will the way you stir tea differ depending on which hemisphere you are from?
2 – What makes a coloured moon?
3 – What is up with muons?

1 – Will the way you stir tea differ depending on which hemisphere you are from?

The question sounded just as weird to me too. Clockwise, isn’t it? But I was wronged when I saw someone, who is also right-handed, do it anticlockwise all the time. A back and forth discussion with people around me led to the question. 

A quick message to my friends led to inconclusive results. However, the concept of how massive water and air bodies swirl in each hemisphere is a long-studied phenomenon. 

Coriolis Effect

The hemisphere does have an effect on how air or water swirls in each hemisphere. This is why you will find hurricanes and tornadoes swirl anticlockwise in the northern hemisphere and the reverse in the southern hemisphere. 

Earth spins about its axis. Because of this, air, water, or even humans closer to the equator spins faster than the ones closer to the poles. When a cyclone is formed, air would want to rush into the centre from all directions. When this happens, we have air rushing towards the centre with different angular velocity. This difference in velocity of particles while they rush towards the centre creates the swirl we see. Because of the way the Earth spins, cyclones in the north go anticlockwise. And yes, the opposite happens in the south. 

Various thought experiments have been conducted based on this effect. There has been a long-standing debate that the way toilet water swirls also depends on which hemisphere it is in. In fact, a whole episode in Simpsons has been featured around this concept. However, when it comes to water swirls in toilets, the toilet design plays a significant role in determining the direction of the water swirl. Also, the Coriolis effect will be negligible on small water bodies.

Where did the teacup go?

So does Coriolis effect have anything to do with the way you stir your cup of tea? Nothing. 

In fact, clockwise or anticlockwise stir, both are wrong. The proper way to stir tea is to go up and down. This mixes the sugar quicker and prevents the tea from spilling out, especially if you get too excited and go really fast. Proper etiquette rules state that you must never let the spoon touch your cup. Keep this in mind. This piece of knowledge will come in handy when you meet the royals someday. 

2 – What makes a coloured moon?

As I read more about the Moon, it keeps fascinating me more. Understanding how the Sun works are straightforward. Even if you were to read more about solar days and equinoxes, I feel the complexity is manageable. But the Moon elevates the need for focus and imagination to a whole new level.

The world this week witnessed a coloured moon. A pink one that too.

We know that the Moon is not a star, i.e. it does not emit its own light. We can see it because the light from the Sun reflects from the surface of the Moon and falls on our eyes. But the interesting thing is the colour moon appears during lunar eclipses, i.e. when the Moon is overshadowed by Earth.

The Moon takes roughly 27 days to revolve around Earth while spinning about its own axis. The orbit for the Moon is at an angle. Lunar eclipses occur when the Earth, the Sun, and the Moon align in a straight line. And when this happens, the Moon is neatly hidden from Sun. However, the Earth still continues to face the Sun. 

To understand why the Moon gets coloured, refresh your memory on how rainbows are formed. When white lights are sent through a prism (water droplets), it is split into different colour spectrums (7). This enables us to witness and lovely colour rainbow. The same thing happens with the light that gets past Earth. It gets refracted and broken into 7 colours. 

Since red light has the longest wavelength, it gets refracted the most towards shadowing the Earth casts. Since the Moon is nestled perfectly behind the Earth in the shadow region where red light alone goes, we witness a red coloured moon. 

What is the colour of light which is refracted the least when it passes  through triangular glass? - Quora
But where did pink coloured Moon come from?

The 7 colours of the visible spectrum do not have pink. Yet we witness pink coloured moons often. The reason for this is because of what lies in our atmosphere. Dust particles, pollution, and clouds affect the hue of red that falls on the Moon. This is why we sometimes get pink as well. 

Curiosity stuff… Now you know.

3 – What is up with muons?

It concerns me that the fundamentals I learnt in school need to be revised. It worries me because soon, my nieces and nephews will come and tell me, “Uncle Arun, don’t you even know the basics? How did you up end up getting a job?”

I agree that is a little dramatic, but nevertheless, with the pace at which science and technology are evolving, we astounding. It is our job to stay abreast with it. 

Scientists working in the Muon G-2 Experiment have now stumbled upon a new 5th fundamental force in nature. Muons are similar to electrons but are 400 times heavier. Through experiments, scientists have found that the muons wobble at a different rate, leading to the hypothesis that there is another fundamental force in nature.

In the natural state, muons are constantly occurring in the upper layers of the atmosphere. When helium and hydrogen collide, a shower of cosmic rays happens. Muons being one of them. These muons have a lifespan of 2.2 microseconds. In this timespan, muons can travel around 660 m.

But wait…

If a muon has such a short life span for it to exists and travels less than a kilometre, how did it find its way to Earth’s surface for people to first discover it?

The answer is time dilation. 

Time dilation is a concept that came out of the theory of relativity. When objects travel at the speed of light, time would appear to move slower, and the distance would seem extended. Because of this phenomenon, 2.2 microseconds and 660 m for the muons is actually 220 microseconds and 66 km for us. Because of this concept, a great experiment to prove relativity.

A lot of science load down for you all this week. With the 4th of May is coming up soon, I could only say May the 4th be with you.

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