My name is Karen Masters, and I’m currently the lead scientist in the Galaxy Zoo science team. I’ve been involved in Galaxy Zoo (and a cheerleader for the Zooniverse) for well over a decade. As well as writing many scientific papers enabled by your classifications (thanks as always for those) I enjoy writing about science in other ways. In my latest book “The Astronomers Library”, a beautiful pictorial walk through the history of books about all areas of astronomy, I was able to write a bit about the history of galaxy classification. 

The first recorded mention of a galaxy I found is in “The Book of the Images of the Fixed Stars”, from 10th century Persia. This book is a complete atlas of the night sky as known in the Arabic world during this time. It contains mention of a “little cloud” in the constellation Andromeda (or “The Big Fish” in the Arabic tradition), which today we call the Andromeda galaxy – our nearest large neighbouring galaxy. It would be another nine-hundred years before the first mention of spiral structure in a galaxy, which were found in the first observations of the Whirlpool galaxy, by a Irish astronomer named Lord Rosse, published as a scientific letter in 1845.  

I hope you enjoyed this small story of the history of galaxy classification. Galaxy Zoo is a part of that history now, and a part I feel proud to have been involved in. Thanks again for all your classifications. 

Image caption: Clockwise from top left – (1) a Sloan Digital Sky Survey composite (Credit: SDSS) showing the Andromeda galaxy, which is larger on the sky than the full Moon, but very faint; (2) a page from the 10th century book “The Book of the Images of the Fixed Stars” showing the first recorded observations of Andromeda  – the fuzzy patch near the nose of the fish (Credit: Al-Sufi; now in public domain); (3) a Hubble Space Telescope image of the Whirlpool galaxy (Credit: NASA/ESA/HST); (4) the first recorded observation of spiral arms in the Whirlpool galaxy from 1845 (Credit:William Parsons, 3rd Earl of Rosse).