Janus is here

Here’s some science to think about for the new year. Now the earth moves round the sun once in a year. The earth’s axis is tilted at an angle. Here is the thought – Suppose you go out everyday at the SAME time and mark the position of the sun as a dot in the sky throughout the year with an imaginary pen…You would get exactly 365 dots. So how would the 365 dots look like? Would all the dots crowd together in the same place, making it a single dot? Or would they form a random smattering of dots, roughly in the same place? Would they form any specific curve, like a circle or an ellipse?

Normally you’d expect that the sun’s position on a specific time will be the same throughout the year, but things are not so simple. The earth spins around itself not erect, but at a tilt. That’s why the sun rises earlier in summer than in winter. The tilt is what causes the seasons. So the first option definitely isn’t the answer.

The motion of the earth around the sun is periodic – it repeats itself once in 365 days, so you should expect something that loops itself every year to be the answer. In fact, the dots form a perfect elongated figure “8” called analemma- something that makes weird sense for this new year.

The top and bottom ends of the ‘8’ correspond to the summer and winter solstices, and the center corresponds to the equinox . You could make something like a sundial with this idea – Take a stick, fix it and note the shadow of the stick at the same time everyday (or every month – you would still get the outline of an 8) and mark the month. I made a crude one by taking readings at 12 o’clock every month….

analemma

I took the pic on Jan 1st 2008, 12 noon. See the shadow pointing toward ‘January’?

Here’s my idea of a new year greeting card. 🙂

analemma2

Sorry for the high resolution…didn’t have time to shorten it.

Janus is the Roman god of gateways and openings, of beginnings and endings…that’s why January is named after him. Again, wish you a happy new year.

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