Galaxy Zoo Volunteers Share Pain and Glory of Research
The Sloan Digital Sky Survey (SDSS) has compiled a list of more than 1 million galaxies. To glean information about galaxy evolution, astronomers need to know what type of galaxy each one is: spiral, barred spiral, elliptical, or something else. The only reliable way to classify galaxies is to look at each one, but all the world’s astronomers working together couldn’t muster enough eyeballs for the task. A volunteer online effort called Galaxy Zoo, launched in 2007, has classified the entire catalog years ahead of schedule, bringing real statistical rigor to a field used to samples too small to support firm conclusions. The Galaxy Zoo team went on to ask more-complicated classification questions that led to studies they hadn’t thought possible. And in a discussion forum on the Galaxy Zoo Web site, volunteers have pointed to anomalies that on closer inspection have turned out to be genuinely new astronomical objects.
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Here in the Oxford University astrophysics group we’ve been thinking about astronomy games to play with the school and public groups that come to our telescope evenings — do you remember the “Top Trumps” card game? Well how about “Galaxy Top Trumps”?!
If you grew up in the UK then you may have spent your school lunch hour playing this game. It’s a really simple card game: each pack of Top Trumps has a theme – cars, footballers, fighter planes, now they cover pretty much anything you can imagine (except galaxies). For example, each card in a cars pack would have a picture of a car and a handful of numbers for that car, such as its top speed or fuel consumption. The player on the dealer’s left chooses one of these numbers, and players compare the number on the top card in each of their hands. The card with the best number wins the trick, and its owner collects the other cards. Play continues until one player holds all the cards, or lunch hour ends and double maths begins, whichever comes first!
At school we became experts on cars as a result of playing this game (did you know that a diesel Ford Fiesta uses three times less fuel per kilometre than a Land Rover Discovery?). So, we had a first go at making astronomical Top Trumps – we made a pack for stars, and one for planets, and are finding that playing the game is a great way of introducing these objects to people, showing them the wide range of things out there, and giving them an idea of their relative properties. (Did you know that Saturn’s moon Titan is bigger than Mercury? And Betelgeuse is 140,000 times brighter than the Sun?)
Now we’d like to make a Galaxy pack, and we’d like your help! We think galaxies are a perfect theme, and we should be able to design a pack that is fun to play and through which people can learn a little bit about the amazing objects in the Zoo. Designing a mathematically perfect pack can get complicated, as James Grime explains in this great video, so for now we just want to focus on cool galaxies and good numbers to pick!
So, which galaxies and which attributes? There are some starting thoughts below, but what we really want are your ideas! What numbers would you like to see on the cards? Are we missing an interesting class of object? Did we forget your favourite galaxy?! Let us know!
You can head on over to this new forum thread or leave a comment here!
We probably won’t be able to get telescope time to measure new numbers to put on the cards (apparently the Time Allocation Committees aren’t so keen on proposals that are motivated by Top Trumps!), so we need to select attributes that we can either look up or get pretty easily from public data like the SDSS. We think things like radius, stellar mass, colour, star formation rate, supermassive black hole mass and redshift might be good. But what do you think?
As for choosing the galaxies, the obvious place to start is with the best-known, prettiest nearby galaxies that no pack would be complete without: Centaurus A, Andromeda, the Sombrero galaxy and maybe the Omega Centauri globular cluster (Are globular clusters galaxies? It’s a good conversation starter!). Any others? Then we might add one each of the basic Hubble types: elliptical, S0, Sa, Sb, Sc and Irregular (let us know if you have a favourite!). Then with all the recent Galaxy Zoo work on bars, we could include both barred and unbarred examples of these — which would make the best cards? We might also want examples of some of the unusual samples defined by Zooites: green peas and red spirals. And what about particular Zoo favourites like Hanny’s Voorwerp? Does that belong in the galaxies pack?