Pilsner, Polaris and the planets
Sitting in the old town square, Prague, in December last autumn, whilst pondering over a Pilsner or two, I looked up at the wonderful astronomical clock.
The clock's artistic beauty and apparent technological sophistication is quite overwhelming, especially when you consider that it was built in 1410 when the world still believed that the Earth was the centre of the universe. Only after studying it for a while can you begin to appreciate this truly magnificent monument to man's fascination with the heavens.
Time to sailors is probably the most important aspect of navigation. Our GPS, for instance, relies on it as well as its ability to receive a radio signal from the satellites. But, did you know that due to the 11-year sun cycle, solar flares could disrupt its accuracy in 2012 and that the weakness of the signal is the equivalent to looking at a 100 watt light bulb from 12,000 miles away?!
One Pilsner later I remembered a quote by Henry Dobson: "Time goes, you say? Ah no! Alas, time stays, we go." Significant, when you consider that according to some theorists the world will be coming to an end in 2012.
Don't panic if you lose your time or the GPS or just want to look up and watch Sky TV for free; read on for this year's celestial delights that can be observed in the Solent by both local yachtsmen and visiting seafarers to our shores.
I will begin with April 2012; this month is great for planet spotting as all five visible ones are above the horizon in the night. Venus is in the evening sky to the west. Jupiter, the giant planet, slips down into the dusk twilight. Mars is visible all night. Saturn will also be visible all night on 15 April. An interesting fact is that Saturn has a density less than that that of water so if you were to plop it into an ocean, it would float. Mercury, technically, is a morning planet - though visible it will be lost in the bright dawn glow.
Next, let's take a look at the August sky. On the evenings of 13 and 14 August you’ll find Spica, Mars and Saturn in line. This will be a great opportunity to compare celestial colours whilst viewing a blue-white star against a yellow and a red planet.
There will be two full Moons this month on 2 and 31 August. This quite rare event is known as a Blue Moon month, caused by it being a leap year.
Finally, if you are still sailing in November then the night of 16 to 17 November sees the maximum of the Leonid meteor shower. We have good observing conditions this year, as the Moon sets early. Also, take a look in the morning sky on 27 November when Venus and Saturn are just a degree apart, a striking sight.
Ursa Major is one of my favourite constellations, which from the Solent can be seen at all times throughout the year. Its seven brightest stars are called 'The Plough', a shape from which it takes its name. The two end stars of the 'bowl' point directly towards the Pole Star, Polaris, a star I call "The Special One".
Location, location, location
Due to the fact that Polaris sits above the North Pole with just a 1° oscillation above it - makes it a great star to obtain a rough estimate of latitude from.
At the Pole, Polaris would be 90° above your head, the angle of the star to the horizon would also be 90° which is the same as the latitude at the Pole, 90° N.
If you then walk 2,172 nm due South on the 001°17'.0 W meridian you would arrive at Calshot Spit. Polaris will then appear to be at 50°48' in the sky, the same as Calshot's latitude. Walk another 3,228 nm to the Equator and Polaris will now be sitting on the horizon at an angle of 0°. You guessed it! Same latitude as the Equator, 0° N/S.
So, simply put, whatever the angle of Polaris is in the sky it will correspond roughly to your latitude.
Whilst you work that one out it's time for me to order another Pilsner to help me provoke the pen to describe a fun and interesting way to find time at sea using The Plough and Polaris.
Stokey's celestial clock
The clock in the night sky is centred around Polaris but reversed; meaning 12 is at six and nine is at three.
Example 1: April - Merak and Dubhe are at five on the celestial clock. Double the month (4 x 2) equals eight, and double the hour (5 x 2) equals 10. The total, 18, taken from 41.50 gives 23.50 which is 2330 GMT.
Example 2: July - Merak and Dubhe are at three on the celestial clock. Double the month (7 x 2) equals 14, and double the hour (3 x 2) equals six. The total, 20, taken from 41.50 gives 21.50 which is 2130 GMT. However, if having taken your doubled sum away from 41.50 your are left with a figure greater than 24, then you need to take 24 (hours) off this to get your time.
Example 3: March - Merak and Dubhe are at two on the celestial clock. Double the month (3 x 2) equals six, double the hour (2 x 2) equals four. The total, 10, taken from 41.50 gives 31.50, so deduct 24 to get 7.50 or 0730 GMT. Or, if your doubled sum is greater than 41.50 you need to take 24 (hours) away from the doubled sum before deducting it from 41.50.
Example 4: December - Merak and Dubhe are at 11 on the celestial clock. Double the month (12 x 2) equals 24, double the hour (11 x 2) equals 22. The total, 46, less 24 (hours) is 22, taken from 41.50 gives 19.50 or 1930 GMT.
An interesting thought…
If Stokey's clock works on 22 December 2012, then the theorists got it wrong about the world ending on 21 December 2012!
However, what if they were right?
There are dozens of theories about what might happen. Some claim the Earth will experience a polar shift, solar storm, or alien invasion. Others say that after 2012, the Earth will experience a period of terrible destruction followed by a new age of peace and enlightenment. Some even think that God is coming to destroy all the naughty people on earth (that's me gone then!). A few claim that in 2012, a secret government will accomplish its goal of total world domination.
What should we do in the event that it might happen?
- Go sailing more often.
- Book yourself on an astro navigation course and learn how to use a celestial GPS (Gentlemen's Position Fixing System) - the sextant.
Finally: "Do not put off till tomorrow what you can do today because… if you like it today you can do it tomorrow as well."
One Pilsner for the road please.
- internationaloceanservices.co.uk/ International Ocean Services website