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Galaxy photos

2010 February 9
by Steven

Here is an outline of an astronomy-based activity, devised by Prof. Mike Merrifield, which teaches students about galaxies, classification schemes, real-world data and presentation skills. The astronomy group at the University of Nottingham have run this activity for sixth-form students very successfully, and this is the version described below, but the activity is adaptable to a wide range of ages, from early high school through to undergraduates.

The activity starts with a brief talk on the general concept of classification and why it is worth doing. Then the students are divided into teams of about five and each team given fifty prints of galaxy photos to look at. Without any specific guidance regarding galaxy morphologies or existing classification schemes, they are asked to devise a way of classifying the galaxies themselves and create poster, using the photos as well as blank paper and marker pens, to explain their classification scheme. The poster can simply be made on the table, and then photographed and projected, or it could be made by sticking/pinning the photos to a board, etc. Each team gives a very short (2 minute) presentation to explain their classification scheme and what they think it tells us about galaxies. Finally, we give a summary, with a brief explanation of the classification schemes used by professional astronomers, which usually correspond quite well with what most of the students come up with.

It is best if there are some astronomers wandering around during the activity to give guidance, encourage the students to think about what it means for galaxies to have different shapes, colours, etc. and answer their questions at a level appropriate for the group. If you are having difficulty locating some astronomers, you could ask us, or your nearest university astronomy department.

Here are the pictures I have put together for this exercise:

These archives contain 400 images sized to fit nicely onto standard 6×4″ prints. The images are of the brightest galaxies in the Sloan Digital Sky Survey (SDSS). (Technically they form a magnitude limited sample (r<14), with wide limits on R90 (5″ < R90 < 30″) to avoid very small or big objects.) All of these galaxies, and quarter of a million more, are included in Galaxy Zoo. We gratefully acknowledge the Sloan Digital Sky Survey (SDSS) for obtaining these images and making them publicly available for educational use. Each image contains the SDSS ObjID, so you can look up more information about individual galaxies using the SkyServer Quick Look tool.

Mike has also provided a Powerpoint presentation he uses to introduce the activity:

An example photo:

2 Responses leave one →
  1. Kate permalink
    November 5, 2016

    Do you have the SDSS object ids for these? I would like to produce tactile graphics of these images but need to produce and inverse gray of each first.

  2. Steven permalink*
    January 3, 2017

    The image filenames are the SDSS objids, they are also given in the corner of each image. Converting to inverse grayscale would be easy with ImageMagick.

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