All Is Not Uniform In The Cosmos

All-Is-Not-Uniform-In-The-CosmosQuestion: Does the spring equinox always fall on the same date each year?

Answer: No.  It can fall on the 19th, 20th or 21st of March

I had always assumed that the spring equinox fell on the same date each year but that is not the case and Graeme’s post last week got me thinking about the ordering of the cosmos.  It turns out that a number of things that I had thought of as unquestionable truths are not that at all.  Let’s look at a few more of the facts that I have uncovered.

The world is round

Well actually, no it’s not!  In truth the Earth is squashed flat at its poles and at the equator it bulges a little.  In technical terms the Earth is an “Oblate spheroid”.  So how much is it flattened and how much does it bulge!  The easiest way to describe it is to say that the distance between the centre of the Earth at the poles is 13 miles less than the distance between the centre of the Earth at the equator.  That’s not much in the 3,959 miles that is generally recognized as the radius of the Earth but it’s enough for the scientists to assert that the Earth is NOT round. See Scientific America for more details.

The Earth spins at a consistent speed

No it doesn’t – the Earth’s rotation around its own axis is gradually slowing down.  It turns out that because of this, we are gradually “gaining” about one and a half seconds each year.  So, if you were expecting 31,622,400 seconds this year (remembering it’s a leap year!) then you might be pleasantly surprised to know that in “Celestial Time” you can look forward to about 31,622,401.5 seconds of “Atomic Time”.

The Moon is always the same distance from the Earth

Now this one is a long, long way off the mark.  When the Moon is as far away as it can ever get from the Earth (known as “Apogee) it is 252,088 miles away but when it is as close as it ever comes to the Earth (known as “Perigee”) the moon is 26,465 miles closer.

My illusions that everything in the Cosmos is perfectly systematic and symmetrical have been shattered.   No wonder that the great Alfonso X of Castile (!) said over 700 years ago that “If I had been present at the Creation, I would have given some useful hints for the better ordering of the universe”.

I’m not suggesting that you should ask your children to remember the astronomical facts above. Instead, try to persuade them to remember the difference between “Celestial Time” and “Atomic Time” and get them to understand that “Apogee” is the opposite to “Perigee”.  If nothing else, it will stand them in great stead when they come to participate in competitive quizzes.

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