Speaker profile

The area of the galaxy where the Sun currently resides can be considered as a fairly typical area of the galaxy. This talk will consider the stars within 5 parsecs of the Sun, concentrating on those with particular characteristics e.g. the Alpha Centauri and Sirius systems, Barnard's star and the home of Mr Spock from Star Trek. The talk is not so much of a list as an opportunity to mention many of the characteristics of stars. Woven into the talk are references to measuring distances to stars and the appearance of the Sun and other stars from the stars concerned. The talk will conclude with some thoughts on the status of the Sun in the neighbourhood and the Galaxy.

In the modern age, given the technological methods of telling the time, sundials have been relegated to historical curiosities. However, in former times, they were a vital part of time-keeping and a great deal of information can be gained by looking at sundials. This talk will describe many of the astronomical aspects of sundials and other ways of telling the time by the Sun. The observatory at Jaipur in India (containing the largest sundial in the world) is given due prominence along with the possibility of a larger, more local rival.

In 1885, Edwin Abbott published a book called 'Flatland' which was about a two-dimensional world. The 'hero' was Mr A Square and other inhabitants included triangles, hexagons etc. Other authors have produced different variations on a two-dimensional universe. Such universes can be extended to include astronomy and this talk considers what astronomy would be like in a 2-dimensional universe. One significant change is that gravity is not inverse-square but is instead simply inversely proportional to distance. The shapes of orbits are different as a result. This talk will consider many aspects of astronomy in a 2-dimensional universe including orbits, seasons, eclipses, meteors, aurora etc. The talk will conclude by considering universes with alternative numbers of dimensions, 4-dimensional, 1-dimensional and 0-dimensional. It can be concluded that, other that the 3-dimensional universe, the two-dimensional is most interesting.

A meteor is a small particle which enters the Earth's atmosphere at high speed burning up in the process and being seen as a brief luminous streak from the ground. Most meteors occur in 'showers' which recur on an annual basis; the members of a shower are believed all to originate from the same comet. This talk considers some of the theory of meteor showers and then details visual, photographic and other means of observing and recording meteors. Some recent projects of the BAA meteor section wil be discussed.

Whilst the 'main business' of star i.e. the production of energy takes place in the core there are many interesting processes taking place in the outer layers and atmospheres. The Sun has three layers of atmosphere known as the photosphere, chromosphere and corona. This talk will give a general introduction to the Sun and will then feature some of the phenomena in the atmospheres including the appearance of the corona at eclipses, sunspots, prominences, coronal loops and solar flares. In addition, the Sun influences events in the Earth's atmosphere and the talk will conclude with a description of some of these.

Throughout history there has been the need to keep track of the passing of the days and of longer periods of time. The natural periods of appearance of the Moon and Sun i.e. the month and the year form convenient time periods but fitting those time periods together has proved problematic e.g. 29.55 days in a month and 365.24 days in a year. The Solar, Lunar and Luni-Solar calendars represent different attempts in different parts of the world to combine the time periods. This talk will consider some of the astronomical factors behind calendars and will detail calendars from many parts of the world. The history of the current western calendar will be considered

The orbits of Neptune and Pluto interact and this has recently led to the re-classification of Pluto within the Solar System. However, the interaction of the orbits goes so much further than a mere crossing and has, as its core, the fact that Pluto makes two orbits of the Sun in approximately the time that Neptune takes to do three orbits. A similar but subtly different situation exists for the minor planet Hilda with respect to Jupiter. Hilda makes three orbits in around the same time that Jupiter takes to make two. However, both Pluto and Hilda are the proto-types of a larger collection of object. This talk will consider some of the aspects of the orbits and the surprises that can be unearthed by considering the orbits.

The story of the discovery of the outer planets is a fascinating one, well worthy of a talk in its own right. Following the invention of the telescope around 1600, the discovery of the satellites of Jupiter by Galileo and others has established the principle of discovery of new worlds. This culminated in the discovery, in 1781, of a new planet by William Herschel. Observations of this new planet, called Uranus, suggested the existence of another new planet and, following mathematical calculations, this new planet, called Neptune, was found in 1846. Further searches and calculations led to Pluto being found in 1930. However, there was one event which, had it occurred differently, could have led to a very different story of the discovery. This talk will look at this alternative history, a WHAT IF story. The 'final' state of the alternative history will be compared with the current solar system.

Since the invention of the telescope, the planet Saturn has been an object of fascination due to the globeitself and the surrounding rings. Over these centuries, a vast retinue of moons orbiting Saturn has been discovered with the longest known (Titan) being discovered in the 17th Centure while others were discovered at the time of the Voyager probes or later. Many fascinating orbital configurations occur when considering Saturn's moons e.g. the retrograde motion of Phoebe, the anomalous rotation of Hyperion and the co-orbital moons for Tethys and Dione. However, arguably the most fascinating moons may be Janus and Epimethius. These two moons orbit Saturn in very similar orbits (orbital periods differ by half a minute in 16 hours). Every 8 years or so, the two moons come close together and actually exchange orbits. The talk will consider the orbits of Janus and Epimetheus as well as some other aspects of orbits in the Saturn system.

While the main asteroid belt lies between the orbits of Mars and Jupiter, many minor planets there are a significant number that orbit in different parts of the Solar System. One such group is the Trojan minor planets, named after various characters in the Iliad and Oddesey classics. Tnese centre around 60 degrees ahead or behind Jupiter in its orbit but can orbit the Sun in fairly complicated curves. This talk will centre on the Trojan Asteroids from their predciction by Lagrange more than 200 years ago, mentioning their discoveries, and the orbital mechanics that allows them to remain in their positions. The same phenomena also occur at various other points in the solar system and the talk will mention these situations as well.

Astronomy is one are where great contributions are made by both professional and amateurs but in many ways the distinction between the two is somewhat blurred. In fact, it is possible for the same individual to be both a professional and an amateur. The talk will consider the roles of professional astronomers and amateur astronomers including ways in which each group can help and assist the other. The talk will consider some professional projects and some amateur projects. Finally, the talk will consider a figure from history who contributed greatly to the subject by being both a professional and an amateur astronomer.

We all think we know what a day is ! However, astronomically, there are several different kinds of days and they all mean something slightly different. Some of these definitions of the day have consequences relating to the time of year or where you are on the Earth. This talk will look at some of the different kinds of days involved. However, the possible kinds of 'day' expand further when leaving the Earth and going to other planets. Days longer than years exist as do months shorter than days. Sometimes days can go 'in reverse'. Alternatively, the poles can be reversed or the poles and equator are exchanged. Such a variety of things related to the day - in ONE solar system.

It is normal to think of the Copernican Revolution as being Copernicus putting forward his opposition to the format of the universe proposed by Ptolemy with Brahe, Kepler, Galileo and Newton also playing parts. However, this talk notes that there were many others who played a part in the revolution and looks at some of the roles involved.

Generally, after any revolution, there is a period of uncertainty while some of the details are sorted out. Things were not different with the Copernican revolution with some 'loose ends' needing tidied up after the revolution. This talk looks at some of the 'loose ends' and how they were tidied up.

What do we think of as the 'fifth planet' ? Have we always thought the same way about the 'fifth planet' ? This talk will look at various perceptions of the 'fifth planet' including some quite surprising ones.

The recent detection of gravitational waves has cast gravity in a new light. This talk will look at the history of gravity starting with the ancients and the realisation that it affected the outer universe as well as the Earth. Gravity has proved very useful in many circumstances. But what should be our modern view on gravity ?