Here you’ll find brief reports of the talks we’ve heard at Society meetings. In these we try to include any web links or other pointers to further information that were provided by the speaker at the meeting. If you were at one of our meetings and would like to correct or expand the report relating to it then please email our webmaster.
The planet Uranus is named after the Greek god Ouranos, meaning ‘sky’ or ‘heaven’. It is the coldest of the planets, an ice giant with a tumbling orbit which takes 84 years to orbit the Sun. A ‘day’ on Uranus lasts 17¼ hours, so it has very long seasons.
Planets only take a few hundred years to form from proto-planetary discs with a star at the centre. All planets have moons and rings, and if they do not, they have been tampered with.
William Herschel identified a possible ring of Uranus in 1789, but this sighting is generally considered doubtful. The rings of Uranus are very dark and were only confirmed in 1977 with two more discovered from Hubble images in 2005.
The big question about Uranus is why it is tilted on its side. Was this the result of an impact, or did Uranus tip itself over? The magnetic poles are asymmetric and offset from the centre and the magnetosphere is greatly tilted.
The heat generated by the core of Uranus is almost equal to the heat it receives from the Sun, about 3 billion km away.
The atmosphere of Uranus is very active despite being so cold. The Keck telescope has observed bright clouds and high altitude haze. The clouds are made up of methane, ammonia, hydrogen and helium.
The core of Uranus is similar in size to the Earth and is composed of molten rock.
The rings are not very dense so there must be many shepherding moons keeping them in position. The ring system is also asymmetric with many tiny rings.
The moons of Uranus are all medium sized or tiny and dark, therefore they are very old. Their characteristics are quite bizarre. Miranda appears to be inside-out, apparently having been torn to pieces. Its orbital inclination buckles the rings of Uranus. The moon Ariel seems to have been re-surfaced, with the crust cracking open them refreezing.
There is plenty going on in this strange world, and many questions remain to be answered.
Roy Easto from Croydon Astronomical Society led a QI type quiz with two teams of two ‘volunteered’ from the membership. This was a change from our usual Christmas Quiz when everyone participates, but the teams played their parts sportingly and … Continue reading
Chris Lintott was unable to visit us as he was on La Palma, so Tony Sizer stepped into the gap at short notice, and gave us an informative and entertaining talk entitled Violent Universe. The Universe is not as benign … Continue reading
At our April meeting Andrew Norton of the Open University spoke to us about Finding Exoplanets. The idea of exoplanets has been around for a long time, but it is only in more recent years that they have been identified … Continue reading
The subject of March’s OAS meeting was The Antikythera Mechanism and the Mechanical Universe and it was presented by Professor Mike Edmunds. He started his talk with a brief history of its discovery. In 1901/2 a hoard of magnificent objects … Continue reading
Our November meeting was addressed by Jack Carlyle, a PhD student at MSSL, who gave us an entertaining and informative talk on how they observe the Sun. With the help of some amazing animations, including one of a collapsing sun, … Continue reading
Our May meeting was addressed by Alec Boksenberg, who gave us a lively talk about The Intergalactic Medium and Other Things. This was a very interesting and wide ranging talk including evidence that dark matter must exist. He said that … Continue reading
Our April meeting was addressed by Paul Money, who gave us a lively talk about his favourite Images of the Universe volume 1. He introduced 10 images and gave an interesting insight into each one. These included diverse topics such … Continue reading
Our October meeting was addressed by Andrew Coates (Mullard Space Science Laboratory), who gave us a talk about ExoMars. Miriam writes: This was a very informative talk about exploration of Mars, and how MSSL is working on an instrument called … Continue reading
Our October meeting was addressed by Brendan Owens (Royal Observatory, Greenwich), who gave us a talk with the title Solar Secrets: Understanding our Star, the Sun. Miriam writes: We were given a whistle-stop tour of the Sun covering sun spots, … Continue reading
Our August meeting was addressed by Alan Aylward (UCL), who gave us a talk with the title Colouring the Sky. Miriam writes: We had an eventful start to this meeting as were locked out at BEECHE! Fortunately Carole was able … Continue reading
Our July meeting was addressed by Roger O’Brian, who gave us a talk with the title Dark Energy and Dark Matter. Miriam writes: Why don’t stars escape from their galaxies? Why doesn’t dark matter fall into black holes? Questions, conundrums … Continue reading