To study and encourage popular interest in all branches of Science.

Newsletter August 2009


Well, we were expecting it really. When did builders ever quote an accurate completion date?

The work on the crypt room at the church is behind schedule and this means that we have had to change the venue for the first meeting of the session. We expect things to return to normal for the October meeting but to make sure, please check our web site

Our first meeting on Thursday September 10th will be held at: Age Concern Resource Centre, Henderson Court, Prince Arthur Road Hampstead NW3 on the corner of Fitzjohn's Avenue. This is the same location as the last two meetings of the last session. If you are in any doubt about the location, please consult the map which can be found on our web site.

The subject of the first meeting is: SCIENTIFIC METHODS IN ARCHAEOLOGY and the lecturer is Dr. Caroline Cartwright from the British Museum. The October meeting (Thursday 8th Oct.) will hopefully be in the crypt room at St. John's Church and the subject will be: MAGNETIC FIELDS IN THE SOLAR SYSTEM to be given by: Professor David Price (Department of Earth Sciences) University College London.

Enclosed with this Newsletter you will find our lecture programme card for the forthcoming session. I am sure you will agree that once again our Programme Secretary, Jim Brightwell has put together a programme covering a wide range of diverse and interesting topics

As members who attended the AGM will be aware, Peter Wallis has now retired from the position of Hon.Treasurer. Our new Treasurer and Membership Secretary is John Tennant and members can help John by renewing their subscriptions, which fall due on October 1st, promptly. His address is: 121 Victoria Avenue Wembley MIDDX HA9 6PZ and it is printed on the back of the programme card. Why not take advantage of the reduced rate for payment made by Bankers Order?

COUNCIL FOR 2009/10:- PRESIDENT/Astro.SecDouglas Daniels
. ASSISTANT Astro. SecSimon Lang
. ORDINARY MEMBERS OF COUNCIL:- Hemant Desai, Leo McLaughlin, Nayna Kumari, Elizabeth Davies.


We are arranging a visit to the Diamond Light Source at Harwell Science and Innovation Campus. See web site:

Diamond Light Source is the UK national synchrotron facility. It generates brilliant beams of light, from infra-red to X-rays, which are used in a wide range of applications, from structural biology through fundamental physics and chemistry to cultural heritage. They have an open day on Saturday 3rd October 2009. Visitors need to register to obtain free tickets. If you wish to attend this event, please contact: Rob Grant: Daytime telephone number: 020 7625 7744 (Rob or Sarah). E-mail with name Rob Grant no spaces and domain name (please use Subject: Diamond when e-mailing). The data required for each visitor is: Title, First Name, Surname, Car Registration Number (optional) & Mobility requirement (optional). We are offered the following advice/restrictions by the organizers:

"Due to the size of the facility, the guided tour will involve extensive walking, so we advise all visitors to wear comfortable footwear. Due to the nature of the facility, we do not admit visitors under the age of 5 and a minimum age of 10 years is recommended. We have very few restrictions due to health or mobility issues, although we ask you to tell us of any special requirements during registration."

The session typically lasts about 2 hours and consists of a talk followed by a guided tour of the facility.


A total Solar Eclipse took place on July 22nd visible from locations in south-east Asia. Several of our members including Jerry Workman, Jim Brightwell, David Brown and Trevor Law, travelled to several locations in China and south-east Asia to witness the event. The eclipse featured a very long - 6 minute totality and promised to be a spectacular event. However, poor weather conditions over the whole area obscured the eclipse. Jim Brightwell reports that from Shanghai it was raining during the entire event and brought back memories of the HSS eclipse expedition to Cornwall in 1999.


On July 19th 2009, Australian amateur astronomer Anthony Wesley was imaging Jupiter with a 14-inch Newtonian reflector from his observatory in Marrumbateman NSW. He noticed a dark spot in Jupiter's south polar region. At first he thought it was a shadow transit, but then observed that it was rotating with the planet. The dark spot had the appearance of the scars left by the impacts of comet Shoemaker-Levy in July 1994. It seems certain that Jupiter has once again suffered an impact from a comet or small asteroid. Members with moderate sized telescopes may like to observe this feature before it fades. It was located at approx LCM (System 3) 315°, high in the south polar region. Full discovery details and images are on: and at:


A short while ago, I happened to watch the television quiz programme QI, which apparently stands for 'Quite Interesting.' During the programme, hosted by Stephen Fry, it was boldly stated that the Earth had two moons! This is of course totally incorrect. So to put the matter right I have written the following account.


Apart from Mercury and Venus, the major (and some minor) planets of the Solar System are all accompanied by moons. In this respect, some are better endowed than others. I have now lost count of Jupiter's and Saturn's moons, every space probe visiting these planets seems to find more of them. But the Earth has only one. Yet there was a time in late 1986 when it was thought that the Earth might have a second moon.

On October 10th 1986 Duncan Waldron developed a photographic plate taken with the UK Schmidt telescope at Siding Spring Observatory in Australia that revealed the presence of an unusual object. This object had in fact been recorded earlier in 1983 by Giovani de Sanctis and Richard West at the European Southern Observatory in Chile. The object appeared to be an asteroid. Its orbit was calculated by Paul Wiegert and Kimmo Innanen at York University in Toronto and Seppo Mikkola at Turku University in Finland.[1] The orbit was highly unusual and the asteroid, formally known as 1983 UH or 1986 TO, was named Cruithne after the leader of the ancient tribe of Picts who long ago roamed Britain, Scotland and Ireland.

Although Cruithne actually orbits the Sun, it is in a 1:1 resonance with the Earth and it orbits the Sun in 363.9 days, very close to Earth's orbital period, so it appears to be accompanying the Earth around the Sun. For this reason it has been described (incorrectly) as Earth's second moon.

Cruithne is a small body just about 5 km. in diameter. It rotates on its axis in about 28 hours and its closest approach to the Earth is about 12 million kilometres. Its orbit is inclined at about 19.8 degrees and since its orbit and the Earth's do not cross, there is little or no chance of a collision, which is fortunate as a 5km. asteroid could make a nasty dent!

Because of Cruithne's greater orbital eccentricity, its orbital speed and distance from the Sun varies more than the Earth's does, this produces an odd effect, as if Cruithne's orbit is kidney shaped as seen from our perspective, and as it takes slightly less than a year to complete a circuit, the Earth slowly lags behind. Then as the years pass, Cruithne seems to be catching the Earth up from the opposite direction. There then comes a time when Cruithne will be seen to make annual close approaches to the Earth. When this occurs, about every 385 years, the Earth's gravitational field will alter Cruithne's orbit by as much as half a million kilometres and similarly, Cruithne will alter Earth's orbit but only by a few centimetres. Because of this change, Cruithne will now take slightly more than a year to orbit the Sun. Then Cruithne's orbit appears to move away from the Earth in the opposite direction and instead of lagging behind, the Earth now appears to be overtaking Cruithne.

And so the strange celestial dance continues, taking 770 years to complete a cycle. With the Earth alternately speeding up and slowing down Cruithne's orbital period, the two partners move towards and then away from one another as they both orbit the Sun. Cruithne's next close approach to Earth (perigee) will be in 2292 when it will be just 12.5 million kilometres away. At such a time Cruithne will be at its brightest but at a magnitude of just +16, it will not be shedding any extra 'moonlight' on to the Earth, in fact it will be a very difficult object to find!

Cruithne, is not Earth's second moon, it is merely an asteroid, but one with a unique relationship with our planet, a relationship that has existed for millions of years and it is not alone. In recent years, three more near-Earth asteroids (NEAs) with similar resonant orbits have been discovered. It is not entirely out of the question that one or more of these bodies might at some time in the distant future actually become a true satellite of the Earth, but for now the Earth has but one moon.

[1]Paul Wiegert, Kimmo Innanen, Seppo Mikkola - Nature June 12th 1997. Back


In April, the long-range weather forecast predicted a 'heat-wave' summer, some 'authorities' even warning of 'life threatening' temperatures and of course linking it with 'climate change' and 'global warming'. Well, once again the accuracy of long-range weather forecasting has been brought into question. If you want to know what the weather in August will be like, best look at the weather conditions in mid July.

It has long been a tradition in the British Isles, that if it rains on St. Swithin's day (July 15th), then it will rain for the next 40 days and we will experience a cool wet summer.

'St. Swithin's day if thou dost rain, for forty days it will remain,
St. Swithin's day if thou be fair, for forty days 'twill rain nae mair'

Swithin was the Saxon Bishop of Winchester and when he died in AD 962, he left instructions for his remains to be buried outdoors. There he stayed for 9 years and then the monks decided to bring him in to the Cathedral and bury him in a smart shrine. When they attempted to remove his body on July 15th AD 971, the legend says a great storm broke and it continued to rain for forty days.

Forty days of rain may be an exaggeration but there just could be a grain of truth in the old adage. At this time of year, if the jetstream tracks to the north of the country, weather systems bringing rain pass us by and we enjoy fine weather. But sometimes, the jetstream tracks towards the south of the country and the low pressure systems from the Atlantic bring rain and cooler conditions to much of the British Isles. For some reason, if the jetstream tracks south, it seems to get stuck and remains in that position for quite a while. It is this fluctuating position of the jetstream that determines our summer weather patterns and has done so for centuries. This year it rained on July 15th and at the time of writing, August 7th, the weather is still cool and wet. Weather forecasters nil, St. Swithin 1 - Q.E.D.

Doug Daniels.


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