Finding North, the Season and the Time with the Stars
There are two useful constellations and one asterism in the northern hemisphere that can help us to find north year-round. This works because all of these point in some way to Polaris, the pole star. If we were to draw a line, the Earth's axis would seem to point at Polaris and consequently, the stars also appear to turn around it. Due to the tilt of the Earth, and luckily for us navigators, Polaris always occupies the northern sky. The southern hemisphere does not have a corresponding south star in the same way we have a north star, but south can instead be found using the Southern Cross.
Finding North with Ursa Minor (the Little Dipper or the Little Bear)
Once you've found Ursa Minor, a little kite shaped constellation that looks like the little sibling of the Big Dipper, you've found Polaris and thus the direction of north. Polaris is the last star in Ursa Minor's tail. Living in a place with a fair amount of light pollution, however, I find the stars of Ursa Minor relatively faint, so I tend to rely on the other two methods for finding North instead.
Finding North with the Big Dipper (the Plough)
The Big Dipper is arguably the most recognisable shape in the northern hemisphere sky. The outer edge of the spoon or ladle are made up of the stars Merak and Dubhe which can be used to easily draw a line across the sky to Polaris.
Finding North with Cassiopeia
Cassiopeia appears as a squiggle with sharp points, sometimes like an M or W depending on its position. Imagine Cassiopeia is a W. The centre point of the W is a star known as Gamma Cassiopeiae (γ Cassiopeiae), Tsih or Navi, which also points to Polaris.
The Big and Little Dipper as a Calendar or Maybe a Really Slow Clock
Here's one for any time travellers out there!
Look up and you can tell what season it is by the position of the Big Dipper/the Plough).
Here's how I remember it:
In winter the Big Dipper is a wooden spoon, held up; we're working through our stores and getting resourceful in the kitchen
In spring the Big Dipper is a scoop that we're dumping seeds out of
In the summer the Big Dipper is a sprout growing from a seed
In the autumn it's a scoop again, we fill it up with the fruits of the harvest.
Not much symmetry to this, but I find it memorable!
Ursa Minor can be used similarly. Pointing downward for much of the night between November and December and upward between May and June.
The Big Dipper as an Actual Clock(?!)
The movement of the Big Dipper is reliable enough to be used as a clock.
This one's a bit brain bending but-- Imagine a 24 hour clock. Now imagine it running backwards, with the numbers backwards to match. The stars of Dubhe and Merak that we used to point us to Polaris are now an hour hand.
Timeanddate.com have a calculation for this. Keeping in mind that on the 6th of March at midnight the Big Dipper is in the position in the image above, on any given day or season, you need only imagine where the Dubhe and Merak are pointing on the 24 hour clock, and then subtract this by 2 x the number of months since the 6th of March:
Time = Dipper Time – 2 X the number of months since March 6.
Calculations may be out by half-hour, but I've given this a go and it worked.
