At Noon Today, The Sun Will Be Precisely Overhead

By MUNGAI KIHANYA

The Sunday Nation

Nairobi,

20 March 2005

Today, March 20, 2005 is a special day around the world. At 3:33pm, Kenyan time, the sun will be directly above the equator on its journey towards the northern hemisphere. In the 24-hour duration beginning at 3:33am this morning and ending at 3:33am tomorrow, there will be exactly 12 hours of daylight and 12 hours of night.

For that reason this day is called the equinox and it will occur simultaneously throughout the world – except at the poles, but more on that later. This phenomenon where daylight and nighttime hours are exactly equal occurs twice every year. The next one will be exactly half a year (note: half a year, NOT six months!) from now – that is on 23rd September, when the sun will cross the equator at about 1:13am, Kenyan time heading to the southern hemisphere.

Because the sun will be directly above the equator today, it will rise exactly from the east and set in the west precisely. If you have never known the compass directions from your house, to day is a good day to mark out your bearings: go out in the evening before sunset and note the orientation of the shadows – that will be east-west.

Since most parts of Kenya are near the equator, at noon today, the sun will be directly overhead and our shadows will appear around our feet. But this will not be the case in the non-equatorial regions. Indeed, the sun never appears overhead at any time in the throughout the year in countries outside the tropics.

To understand this, imagine you were travelling northwards at daytime today. As you move, the sun will appear to drift southward (in addition to its normal westward movement). From, say, Cairo, Egypt, at noon today the sun will appear about 25 degrees to the south from overhead and from London, England, it will only rise halfway up (40 degrees) the southern sky.

The question that arises is: can you go far enough in the north until you see the sun setting in the south? The answer is yes! If you cross the North Pole, you will get into the dark side of the planet thus, to you, the sun appears to set in the south. But that should not be surprising at all since, from the North Pole, every direction is south! To appreciate this, look at the globe of the Earth

So, if there is neither east nor west at the poles, from where does the sun rise and set? That is a story for another day… For now, we note that the equinoxes coincide with the start of our two rain seasons in March and September. Some people maintain that if it hasn’t started raining by March 20th, then the rest of the year will be very dry. I don’t know how true the theory is, but let’s wait and see.