Practical Session on Spectroscopy – 3rd January 2019

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A New Year and a New topic for WAS – Practical Spectroscopy! And who better than Lee Sproats of David Hinds/Baader UK to guide us through it?

Was there some nervousness about this? – some thoughts that this was not quite for us? Well, it might have started that way, but as Lee talked us through the construction and operation of the DADOS Slit Spectrograph, he gradually drew us in and members were actively participating and understanding how the instrument worked and was used. Plans to go outside and actually capture a spectrum were thwarted by the weather (and it was bloomin’ freezing out there anyway!!) so we contented ourselves with viewing the spectra generated by the lights in the Hall and the Neon Calibration Lamp. Lee finally demonstrated the rudiments of the BASS software for processing spectra.

Assuming the weather cooperates, we now have the opportunity as a society to try this instrument out – Lee has kindly lent WAS the DADOS instrument he demonstrated for the next month. Neil Hawkins has it and he can be contacted to borrow it.

Sandy Giles

Astronomy and the Speed of Light - Prof Bob Lambourne – 21st November 2018

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To measure distance these days you need, not a ruler, but a clock! For the metre is the length of the path travelled by light in vacuum during a time interval of 1/299792458th of a second.

The metric system was originally conceived as a system of measurement derivable from unchanging phenomena; but technical limitations necessitated the use of artefacts (the prototype metre and prototype kilogram for example) when the metric system was first introduced in France in 1799.

But in the same way that has been done for the metre, from 20th May 2019 the kilogram, ampere, kelvin, and mole will be defined by setting exact numerical values for the Planck constant (h), the elementary electric charge (e), the Boltzmann constant (k), and the Avogadro constant (NA), respectively.

The November lecture from our Vice President Prof Bob Lambourne, focussed on the history of the determination of the speed of light, such that now it is deemed to be a fixed value – a constant in the same way as the Planck or Boltmann constants.

Galileo in 1638 started it, coming up with a value of about 200,000 km/s, but admitting it was actually too fast to measure. Then through the work of Bradley, Huygens and Newton in the 18th Century; Fresnel, Fizeau, Foucault, Michelson and Morley in the 19th Century to arrive at estimates closer to 300,000 km/s; culminating in the theories of Lorentz and Einstein in the 20th Century. Along the way, the notion of the “ether” was invented and discarded, and Einstein’s Theory of Relativity showed how to relate measurements made by observers in a specified state of relative motion. Whilst “c” does represent the speed of light, its real significance is that it is the fundamental constant in all space-time physics.

Not strictly a lecture about astronomy, this was a welcome revision of this corner of the history of science. The Society wishes Bob a happy retirement from his post at the Open University and we are extremely pleased that he will continue to be our Vice President and wants to come back and give us more lectures!

Sandy Giles

Sandy Giles at Wycombe Sound Radio – 13th November 2018

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Continuing his monthly series of chats with Mick Lewis of Wycombe Sound Radio, WAS’s Sandy Giles this month was talking about the use of his new ZWO video camera for taking lunar images. He also fielded a question from a listener recently back from a trip to South America, why could she see more stars in the southern hemisphere that she sees at home – likely because there was less light pollution and atmospheric disturbance. Sandy also discussed the end of one space mission (the Kepler Space Telescope) and the beginning of another (the BepiColombo mission to Mercury).

You can listen to show here: http://listenagain.wycombesound.org.uk/index.php/shows/Afternoons/ and click on, Afternoons_Tuesday 13 November 2018.

Sandy’s next interview will be at 2:00 pm on Tuesday 11th December (106.6 FM).

Photographing the Deep Sky – A Journey through Space and Time Chris Baker – 17th October 2018

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Having visited us a couple of years ago, Chris Baker did not dwell overlong on the description of his telescope five thousand feet up in the mountains of Spain. He is an early pioneer of remote astro-imaging, having available over 2000 hours of imaging time available each year and being able to control, from wherever he is, his 6 inch Takahashi Refractor equipped with a QSI683 CCD camera fitted with eight filters (L, R, G, B, Ha, Hb, SII and OIII).

He primarily wanted to show us his images taken over the last few years with this equipment and chose to present them in order of their distance from Earth, illustrating at the same time what was happening on Earth at the time the light left a particular object.

Having briefly got past the Solar System (he’s not ashamed to admit he’s not a planetry imager!) the first port of call was the Pleiades, the light from which left 440 years ago, when Elizabeth I was our monarch. Demonstrating clearly that faint nebulosity surrounding this cluster (achieved by incorporating a Ha image into the blue channel) we knew from the outset what a treat we could expect for the rest of the evening. Then followed magnificent images of the Dumbbell Nebula (1,350 ly), part of the Veil Nebula known as Pickering’s Triangle (1,470 ly) the Horsehead and Flame Nebulae (1,500 ly) and the Pelican Nebula (1,800 ly).

Onwards and outwards we went – the Elephant’s Trunk (2,600 ly), the Cocoon, Crescent and Rosette Nebulae (all about 3,000 ly) and the Bubble Nebula (7,500 ly). Finally, whilst still in the Milky Way, out to stars as old as the galaxy itself, the globular clusters M13 (22,000 ly), M5 (24,460 ly) and M3 (33,900 ly). All fabulous images in gloriously deep colours, with amazing clarity and depth. Some of these images involved over 50 hours of exposure!

After this of course, a big gap – because we needed to step out to neighbouring galaxies. M31 (2.5 mly), M33 (2.7 mly), M51 (23 mly), the Virgo Cluster (65 mly). Finally Chris showed us an image he took of the furthest object in his collection, Abell 2065, a galaxy cluster one billion light years away!

With great images, an engaging presentational style and a book of his images available for purchase afterwards for those that wanted, we had a most enjoyable evening. And for all of us aspiring astro-imagers, a clear message – must try harder!

Sandy Giles

Aurora - Dr Melanie Windridge – Wednesday 18th July 2018

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Melanie Windridge has explored the science and mythology of the Northern Lights and this month she shared many of the stories of her quest to explore her fascination in and our understanding of the Earth’s Aurora. Melanie is a physicist, specializing in fusion research. She is also an adventurous traveler, particularly at home in the world’s coldest places.

She shared the experience of her visits to many places where the aurora is visible – Lapland, Iceland, Canada, northern Scotland, and Spitzbergen – and of meeting people for whom the Northern Lights plays a significant part of their lives. She travelled, for example, with Sami herdsmen in northern Norway and learned of Sami mythology and the gradual dwindling of their nomadic way of life.


Dr Windridge interweaved these stories with explanations of the science of the Northern Lights. Aurora occur when electrons and protons, which are charged particles and form the greater part of the solar wind, interact with Earth’s magnetic field and elements in the earth's atmosphere. Solar winds stream away from the sun at speeds of between 300 and 750 kilometers per second. They reach the Earth some 30 to 40 hours after leaving the sun. As the electrons enter the earth's upper atmosphere, they will encounter atoms of oxygen and nitrogen at altitudes from 20 to 200 miles above the earth's surface. The colours generated relate to the energy levels available in atoms that are struck. Nitrogen producesthe blue and purple and oxygen produces green and red.

The auroras generally occur in ovals which centre on the magnetic poles and roughly correspond with the Arctic and Antarctic circles. There are times, though, when the lights are farther south, usually when sunspot activity is high. Sunspot activity follows an 11-year cycle. The next peak will occur in 2022.

Melanie highlighted the dangers that space weather poses for satellites in orbit, and for the power grid on the Earth’s surface. She outlined her own efforts to view the aurora, illustrating with her best attempts to capture an image how difficult it is to photograph the aurora’s rapidly-changing structure.

Chris