The Great Bear

The Big Dipper needs no introduction – yet it crossed my mind, this celestial constant might deserve a little ponder. Often mistaken for a constellation, the seven stars – Alkaid, Mizar, Alioth, Megrez, Phecda, Merak and Dubhe – form an Asterism, or subset of stars within a constellation. in this case Ursa Major – the Great Bear.

In November, the Great Bear descends to the lowest point along northern hemisphere horizons. Micmac people of southeast Canada saw this as a sign “earthly” bears went into hibernation, and tree sap returned to the “womb of creation”. Ursa Major appears to touch the earth, winter takes full command. The great bear sleeps, her extremities falling below the horizon yet the Big Dipper manages to hover above the edge of perception.

The Big Dipper doesn’t come and go with seasons, it’s circumpolar, meaning it lies in the same direction as the celestial north pole.  A line drawn outwards from the pole would pass  practically through the Dipper, and intersect with Polaris (the North Star). Earth rotates on its axis around Polaris, stars that are circumpolar to the north pole travel in tight circles around Polaris, therefore visible all year, albeit with a few sways and dips. If the Big Dipper was a clock moving once around Polaris every 24 hours –  the “bowl” would always face Polaris – at 6 o’clock it would appear flat, 3 o’clock standing on the handle, 12 0’clock upside down, and 9 o’clock standing on the bowl.

Lay eyes on the Big Dipper, finding Polaris becomes a simple matter of locating the two outermost stars of the bowl (farthest from the handle) – draw an imaginary line up and beyond for roughly 5 times the depth of the bowl – voila, the North Star.

Think of the Big Dipper as a celestial guide – take comfort in understanding it will never allow you to loose your way. If you see it, you can find north. You don’t need to panic if your GPS craps out – celestial navigation won’t let you down.

http://www.theskyscrapers.org/getting-to-know-the-big-dipper

Image Credit: AlltheSky.com

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