U3A Jodrell Bank Observatory Visit, March 2015 I’m sure you will all instantly recognise the equation z = a(x 2 + y 2) as that of an elliptical parabaloid. This of course, we were informed by Jodrell Bank, describes the shape of the dish of a radio-telescope, so that distant radio waves will be focussed on a receiver in the centre. And who am I to argue with them. 24 intrepid trekkers braved the rain on the 13 th March and climbed the many steps of Hednesford Travel’s coach, to arrive at the Observatory in rural Cheshire. Now part of Manchester University, it was located there on purpose, to be in a better “radio quiet” area, if that is possible these days. Switching off mobile phones was our first request on entering. The obvious landmark that greeted us was the enormous Lovell radio-telescope, 76 metres in diameter, which started receiving signals from outer space in 1957. Although we couldn’t get close enough to touch it, nor get in the control room, we did manage to get a few group photos in front of it before leaving. At least we did see it pan across the sky and rotate on its axis with quite loud grumbling noises. Well, it is an old timer now after all. Lovell managed to get the huge telescope up and running after his wartime development into radar, thinking that the receiving equipment developed could be put to other uses. During a talk from a physicist who also doubles as an educator, we were told about the parts of the electromagnetic spectrum that the Lovell telescope receives, which was from microwave frequencies upwards towards the infra-red bands. Different agencies around the world request data received from Pulsars, Quasars and cosmic microwave background signals, which the telescope can track. To increase the sensitivity of the dish, other radio-telescopes around the world are harnessed to track together with Jodrell. To ensure correct synchronisation of all the dishes, it necessitated the making of an atomic clock for accuracy, which was based at Jodrell, so that time delays between signals from dishes can be compensated. A square kilometre array of dishes is due to be built in South Africa to increase signal power. These will be in the shape of spirals from a central spot, and is being planned by Jodrell Bank engineers. Several spacecraft have also included receivers built at Jodrell, such as Planck. The receiver in the Lovell telescope has to be made so sensitive, that it must be cooled to -260 degrees Centigrade, to reduce electronic noise to virtually zero (typically hiss). This enables very feint radio signals to be heard from outer space, but makes the receivers extremely complex with cooling cryogenics from liquid gases such as nitrogen. Around the area of the lecture theatre were several video and static displays, showing all the areas that Jodrell were involved in. With 35 acres of landscaped gardens, and a café with a wonderful menu, this visit was a very interesting day out, and enjoyed by all. Barry James Cannock Chase U3A