For three years I have been pondering how to solve a tricky riddle. There are so many people who would love to learn about the night sky, but it is very hard to organise an outdoor course for this in this country because the weather is so unreliable. I need to sort the dates for my courses at least a few weeks in advance and it is impossible to predict the conditions that far away. Also, the best times of the year for star, moon and planet-gazing are not the best times for weather. Mid-summer is great for many outdoor activities, but with the late sunsets it is not perfect for stars.

The solution, it dawned on me (pehaps I should say dusked?) is to create a club for those who are interested and then, when the conditions are right I will let everyone know where and when I will be for a couple of hours of guided stargazing. There will be no charge – as there will be no guarantees – but I should be able to give a couple of days notice in most cases and less in a few. Most of these will take place in the South Downs in West Sussex, but I will also endeavour to host a couple of nights when out and about in other parts of the UK or perhaps, in time, abroad. All you need to do to join this club is to come on one of my courses, public or private.

Last night the visibility was great and we enjoyed the nearly full moon, Gemini, Pegasus, Taurus, the Plough, the North Star, Cassiopeia, Jupiter, Cygnus, Auriga, Orion and probably quite a few others! In total we looked at five different ways of finding north from the stars and many other techniques for finding direction.

I took the picture of the moon above last night. It is full today and so was one day off full last night, but it does look quite full. It goes to show how tricky it can be to tell the difference between phases precisely. Everyone can get very close, but I do not know of anyone in the world who can, without fail, gauge the phase of the moon to the day just by looking at it. This has implications for using the slightly involved ‘phase method’ of finding direction (see the book), as for each day you are out in your estimation of the moon’s phase this can throw your estimation of direction out by 12 degrees.

Here is a bit of a red herring from a navigation point of view, but fun all the same… When I was going through my photos this morning I was about to delete an unsteady one of Jupiter (the second one shown here), when I hesitated because I spotted something that jumped out at me. Below the bright Jupiter and in a crooked line there are four stars, but just above them and to the right of Jupiter there is a very small blue smudge. This, as I hoped and suspected, was Uranus. It was not visible to the naked eye last night, but showed up on the longer exposure of this photo. A lovely small ‘discovery’ to start the day with. Not sure my name will go down there with Herschel’s though!

Tristan


I managed to rope in a friend at the end of an evening’s BBQ and together we plumb-bobbed Polaris, set out two posts and then strung a string between them. We checked with a compass and, despite the evening’s beers, we were actually almost spot on!

The next day we checked the shadow at 1.00 (12 noon GMT) and found this lined up on our string. Impressed or what!

Richard

——————

Hi Richard,

I can see I’m going to need to come up with some sort of merit/badge/star system just to complete the back to school experience!

A link that I will have mentioned on the day is here:

http://aa.usno.navy.mil/data/docs/AltAz.php

If you plug in your latitude and longitude, it will give you the altitude and azimuth of the sun (or moon) for a whole day by GMT. Due south is often very close to clock midday, but it can wander off it depending on your longitude and because of something called the ‘equation of time’.

All the best,

Tristan