Want an extra hour in your day? Wait 360m years!

 By MUNGAI KIHANYA

The Sunday Nation

Nairobi,

07 March 2010

I got a strange question came from Kimemia Elijah some time back. He wrote: “Is there a possibility that one day the sun will rise from the west?” It made me wonder what motivated him to ask such a question, so I assumed that he aware that the rotation of the planet on its axis is slowing down.

Yes! Our days are getting longer with time. It has been observed that the time period of rotation of the Earth increases by about one-thousandth of a second every century. In other words, 1,000 centuries (100,000 years) from today, the length of a day will be 24 hours and one second.

Assuming that the slow down will remain constant, we can easily find out how long it will take for the day to get an extra hour, thus: One hour has 3,600 seconds; if it takes 100,000 years to gain one second in a day, then it will take 360 million years for the length of the day to increase to 25 hours.

The next natural question is whether the Earth will one day stop rotating. The answer is yes. But don’t worry about it; it won’t happen in your lifetime, unless you expect to live for 9 billion years.

The slow down of the Earth’s rotations is caused by the tidal movement of the oceans. As the seawater moves from one shoreline to the next, it drags the solid part of the planet against the direction of rotation. This happens every day and consequently the spinning slows down, albeit gently. 

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Another reader going by the name Kayhills, writes: “We're that told the earth is round. [If that is so,] it means at any one time, there's the side facing up and another facing down…some people have their heads upside down – [their] sky is down not up.”

Now, despite the sterling job that geography teachers are doing at school, I know that there are many people who still wonder about this. First of all, the expectation that the sky should be “down” for some people arises from the false assumption that the Earth is round while the (blue) sky is flat. This is not so: the sky and the clouds envelope the Earth. So, wherever you are, as long as you are standing on the ground, the sky will be above your head.

Secondly, there appears to be a general misunderstand of the meaning of “up” and “down”. These two words sound obvious but they are not. “Down” means towards the centre of the Earth; “up” means away from the centre. Once these meanings are understood, the idea that some people have “their heads upside down” is no longer valid.

That kind of thinking is similar to expecting the River Nile to flow from Egypt to Uganda because former drawn above latter on the world map! The truth is that Egypt is closer to the centre of the Earth; therefore it is lower than Uganda. Thus the river flows from the higher country to the lower one!

But why do they draw Egypt above Uganda anyway? I have two thoughts about that – one has to do with pride the other is related to nuts and bolts. I will write about them in a future article.