Lecture by Professor Chris Lintott – “Is the Milky Way Galaxy Special?”

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“Intriguing”, “Stimulating”, “Skilfully explained”, “Superb”, “Funny”. Just some of the comments we received after Chris Lintott’s highly entertaining, thought-provoking and informative lecture about our Milky Way galaxy and its place in the universe.
 
We have tried for a number of years to get this acclaimed astronomer to come to speak to us – often his commitments such as the BBC’s “Sky at Night” or “Stargazing Live” took him away from us. But this time he was able to come. And it was worth the wait!
 
He gave a very personal view on his approach to astronomy – basically, making interpretations of simple observations of the sky to decide things about the universe. Why, for example does the Milky Way appear the way it does? William Herschel in the 18th century was one of the first to map the stars in our galaxy, though he didn’t know he couldn’t see all of them. It took the Spitzer Infra-red Space Telescope to build a proper map, showing our place in the universe and determine that our galaxy had spiral arms – oh, and a bar (“Things are looking up” someone nearby remarked!)
 
But is our galaxy different? Lintott described how in 2007 he and his colleagues started to classify galaxies just on the basis of their appearance (e.g. spiral or elliptical). It turns out that humans are better than machines doing this and one student spent a whole year classifying 50,000 of them – but information was needed on another 900,000! Enter Galaxy Zoo, the crowd-sourced astronomy project which invites members of the public to assist in the morphological classification of large numbers of galaxies. The work was completed in months and duplication of observations helped clear up anomalies.
 
Out of this emerged the Galaxy Colour-Magnitude diagram (analogous to the Hertzprung-Russell diagram for stars) and this is where our galaxy is unusual – it’s green (most are red or blue) and it’s massive for its colour – in this regard we’ve had an unusual history. Nor is our galaxy as active as it should be, albeit it may have been more active as little as 25,000 years ago. Which is a very short time astronomically speaking. Observations of Fermi Bubbles in our galaxy suggest that the black hole at the centre may switch itself on and off on very short timescales. So maybe we are special.
 
On the other hand, there is data to show that about thirty other galaxies have gone from active to silent in the last 50,000 years. Maybe the Milky Way is not abnormally quiet… we’ve just caught it at a quiet phase.
 
The information we have at present is conflicting. We need to get Professor Lintott back again, maybe in year or so, when more data will be available. There’s no doubt everyone who attended this lecture would like that!