Solar Eclipse 2015

Blocking out the sun

If there’s some primitive tribal chief you need to intimidate, tomorrow morning will be your best chance for a while, because tomorrow morning, at 9:30, there will be an almost total lunar eclipse of the sun.  As a matter of fact, in some places, the eclipse will be complete, but most of those places are in the middle of the ocean, which is great news for anyone who needs to intimidate a tribe living in Waterworld, but probably not for the rest of us.

Solar eclipse

If you don’t need to intimidate a primitive chieftain, but just want to see a total eclipse, you’ll have to hurry, because the only places on land where it’s going to be visible are the Faroe Islands and the Svalbard islands off Norway.  Unless, of course, you happen to live in the Faroe Islands, or Svalbard, in which case you don’t have to hurry at all.  Jut get up  at about 8 am, have a light breakfast of puffin and whale blubber, and wait for the sun to be completely obliterated as the Moon passes it.

It’s not just any old moon, by the way, even though it is, of course, exactly the same lump of rock it always was.  But the many moods of the Moon have many different names: the New Moon, the Harvest Moon, the Blue Moon, Keith Moon.  Bad Moon Rising.

This one is the Supermoon, not strictly a scientific term, when our lunar companion passes closest to Earth, its perigee, making it look bigger.  You might have thought that the Moon goes around the Earth in a circle, and you might be wondering why it should be nearer sometimes and further away at other times, but in fact the answer is very simple.  The Moon’s orbit is not circular. It’s elliptical, like a circle that somebody sat on.  Egg-shaped.  This means that sometimes the Moon is very far away from us, sometimes it passes  very near us, as it’s doing at the moment, and sometimes, it’s neither one nor the other.  Much like the Grand Old Duke of York.

Now, when the Moon is very close to us, it has a far stronger gravitational influence on the tides because gravity obeys the inverse-square law.  What does this mean?  Simple.  The bigger the distance between two bodies, the smaller their gravitational attraction, as you might have guessed.  But if you double the distance, you don’t just halve the pull.   You reduce it to a quarter of what it was.

So when the Moon is at its closest, it exerts a a massive pull on the oceans, about 30% more than it does at its apogee, which is a fancy way of saying when it’s furthest away.  It also exerts a massive pull on the rest of the planet, but only the oceans are fluid enough to respond instantly, though the Earth’s crust also displays tidal motion.  And so it causes extremely high tides.  Remember that.  It will come in handy in a minute or two.

As a matter of interest, most orbits are elliptical, but some are not.   In very unusual circumstances, they can be circular, but they can also be parabolic and even hyperbolic, all of which, you’ll instantly point out, are conic sections, based on slices through a cone.  I must come back to that some time because it’s interesting in a geeky, nerdy sort of way, especially since the Moon doesn’t just go around the Earth.  The Earth also goes around the Moon, like a big fat ice-skating man holding hands with a tiny skating girl.

Now.  The Moon isn’t the only celestial body pulling on the oceans.  The Sun is doing the same, so when you put them in a direct line, the tides are going to be truly savage, and here’s where the primitive tribal chieftain comes in, because you can start your mind-fuck long before the eclipse.

Who might the primitive tribal chief be?  Well, any believer in ignorant superstition, really.  George W Bush, some patron of the Iona Institute, an Islamic State leader,  Bishop Eamon Martin.  Who knows?  Enda Kenny, maybe.  It’s hard to imagine anyone more primitive or tribal.

I think this is what Saint Patrick did.

Start by threatening to cause a flood.  As the water rises, keep threatening to take away the Sun.  Raise your threats to a crescendo as the water laps around their feet until finally, with a close eye on your watch, you can inflict the final punishment.

Enough of your insolence!  I shall take away the day.  Sun, begone!

You need to have their full, undivided attention when the Moon gets about  quarter of the way across the solar disc, but don’t waste this moment.  Scream at them to submit.  Imagine you’re Davey Fitz after your team has just been beaten by Limerick.  That sort of intensity.

You have to grab them by the metaphorical scrotum before Umbra declines into Penumbra once more.   I’m telling you now.  You only have a few minutes, but if you do it right, you will be the new tribal chieftain, while the old one is dragged off to explore the joys of being a shrunken head.

Should you happen to find a Stargate, and a planet full of astonishingly-attractive young ladies, or young men, depending on your inclination, these principles are equally valid, but let me give you one word of advice.

Forget the bit about being Davey Fitz.

 

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