Today’s guest blogger is veteran forum member Geoff Roynon.

My interest in the night sky (and astronomy) goes back to the late 1950s when I was growing up in South Africa and we were blessed with dark skies. I soon learned to spot the Southern Cross and Orion and various other “star shapes” in the night sky. We also saw some of the early satellites going by overhead so this must have been 1958/59.

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What are these mysterious buttons? You shouldn’t have to wait too long to find out (we’re still testing…). 

Final testing underway… 

Hello to everyone that found Galaxy Zoo today through Gregg Easterbrook’s Tuesday Morning Quarterback column on espn.com. We welcome you to Galaxy Zoo, and we are glad to have you here as we journey together to understand more about our universe.

There is also a Galaxy Zoo forum with active discussions on all topics, including people sharing some of the beautiful galaxy pictures they have seen on the site. Take a look at the Threads to help you find your way around Galaxy Zoo for an introduction to the forum. There is also a thread with more information about Hanny’s Voorwerp.

We’re looking forward to seeing you around!

This blog post is a continuation from the previous blog post on Spin Correlations. See that post for the introduction to what comes here.

Imagine throwing a handful of spinning ballerinas into an empty space (since they are in empty space now, there is no need to for them to be ice-skaters). We can associate a thumb with each one in a similar manner as we did with galaxies in the last post. This thumb points towards her head if the ballerina herself thinks that she is rotating anti-clockwise, and towards her feet if she things she is rotating clockwise. Alternatively, we can also wind our right-hand fingers around her body in the sense in which she is spinning and look at where the thumb is pointing - this will give consistent results.

If ballerinas are thrown in at random, there are no correlations in their spinning directions. We discussed the concept of correlation in the previous post: if there are no correlations, the two neighbouring galaxies are equally likely to have parallel, anti-parallel or perpendicular spin directions - in other words, by knowing a spin direction of one galaxy, you can’t deduce anything about the spin direction of its galactic neighbour. This is illustrated here by these five animated photos of a spinning girl:

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