Five years ago, shortly after the creation of the Eddington Society, Christopher Lintott the copresenter of the Sky at Night came to speak to the fledgling society. Half a decade and one doctorate later, he came back.
This time the venue was the room within Kendal Museum that the Our Amazing Universe exhibition was being held. This building is in fact next to the building in which the original talk was held. This meant he spoke watched by the medals of Sir Arthur Stanley Eddington and surrounded by astronomical pictures galore.
He spoke to a full room of members of EAS and other local societies invited down for the evening. Such was demand that the number of places had to be strictly limited and so no public announcement of the lecture was made, as had been the original plan.
The talk was on Galaxy Zoo – its origins, its permutations through the years and its future. He was a well received humorous speaker delving into the superstructure, expansion and composition of the universe, how it is modelled and observed. This he related to large surveys of the most distant parts of the universe, through observations of the many, many millions of galaxies out there that are captured by single sky surveys. One of these is the Sloan Digital Sky Survey, which gave him a million galaxies to classify. He handed the project over to a PhD student, who decided after 50,000 he wasn’t going to finish the rest. Then Galaxy Zoo was born to try and get through the rest of them.
After a short tutorial, any member of the public registered with the website can then go on to classify galaxies picked from the survey. Initially, the idea was to go for spiral, elliptical, irregular and then state whether or not the spiral seemed to go clockwise or anticlockwise. It was found that users had a bias for clockwise rotation, which needed correcting for. But as well as that, the Zoo made some interesting discoveries in the 30% of objects that wouldn’t fit the classification scheme if a computer had been doing the work. Things like the Voorwerp – the afterglow of a galaxy’s central black hole’s jet, which had relatively recently (astronomically speaking) switched off. Then there were the Green Peas, things a tenth of the size of the Milky Way with a hundred times the star forming rate, believed to be the result of mergers of small galaxies.
Chris then moved us into the present with Galaxy Zoo two – which is the screen that appears at the Galaxy Zoo website at the time of writing. This has more categories for classifying the galaxies and there are more galaxies to classify. Amongst them are galaxies from Sloan Stripe 82. This was an area of the sky survey that had been imaged several times over in order to get a ‘video’ of the night sky rather than just a picture. This would reveal supernovae and variable stars, asteroids and comets as well as other transient phenomena. On the other hand, if you just take a load of night sky images and add them together (“stack” them), then you synthesise a longer exposure image and get fainter objects – ie more galaxies. There’s also been a recent experiment where the ‘video’ was used to identify 23/4 supernovae.
Finally, Chris spoke about the future of galaxy zoo, with more data and more uses like the supernova study. Galaxy Zoo is increasing its hold on the night sky with collaborations such as one with Microsoft’s World Wide Telescope, whereby they swap data – classification details from Galaxy Zoo and areas of the sky information from WWT.
After the talk, the audience had the chance to wander round the exhibits in the room. Then a few of us retired to the Castle Inn, where Chris was grilled further over sandwiches and chips. He was even recognised by someone in the pub and was himself delighted to recognise a beer he drank at home in Torbay that he had been unable to find elsewhere in the country.
Stuart Atkinson’s write-up of the event, with pictures without my special brand of blurring, is available here.