Navigating the Winter sky

An unseasonal post – but promising because I know that it will be at least six months before someone can check my veracity!

Someone asked me recently how to navigate the stars of the winter sky. Because the ‘winter sky’ refers to the sky from October till about March, it doesn’t coincide with the fortnight that passes for the Chennai winter, and is actually valid for a significant part of the year.

Start with Orion, which is at the bottom left side of the photo below – and if you can’t recognize Orion, you’ll have to have someone point it out to you. It’s really the starting point for navigating the winter sky.

One star in Orion is visibly ‘redder’ than the others, and that one’s Betelguse. The star diagonally opposite Betelguse (on the other side of the belt) is Rigel.

Winter Constellations and Zodiacal light

To the top and right of Orion is a constellation with 4 bright stars in a trapezoid configuration, and that’s Canis Major – the Big Dog. The brightest star in Canis Major is Sirius, which is also the brightest star in the Winter sky.

Forming a roughly equilateral triangle with Sirius and Betelguse is another bright star, called Procyon. There’s a little, fairly dim star next to Procyon, and these two stars together form Canis Minor, the Little Dog.

The star nearest to Betelguse in Orion (on the same side of the belt) is called Bellatrix. If you join Bellatrix and Betelguse and extend the line, the star you hit upon is called Aldebaran – which forms the ‘eye of the bull’ Taurus. Taurus is a rather faint constellation except for Aldebaran. If you extend that line beyond Aldebaran, about the same distance as Betelguse to Aldebaran on the other side of Aldebaran, you will see the faint, beautiful Pleiades cluster. I can only ever see Pleiades’s stars with a pair of binoculars – otherwise it looks like a faint blob to me.

But onto the next star. If you now draw a circle with the points Aldebaran, Rigel, Sirius and Procyon, you will hit a pair of stars which are near each other, and these are the main stars of Gemini – Pollux and Castor, in that order.

And if you close the circle back to Aldebaran, you will find that it passes through one more bright star – Capella, the brightest star in the constellation Auriga, the chariot.

This circle is my main compass in the winter sky. It’s called the Winter circle, and though it isn’t a ‘constellation’, it’s nonetheless a very prominent and very easy way of navigating the night sky.

As an aside, I became interested in astronomy when, after one day’s heavy drinking with a few cousins, I took my excellent binoculars outside and looked at the sky. I saw a multitude of stars that I had never seen before! Interested as always in the unknown lurking amongst the known, I resolved to use the binoculars and navigate the night sky. This was around October last year; I’m still figuring out the summer sky.


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