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					AstroProjects                                                   Galaxy challenge
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                                                       Galaxy Challenge
Browse thousands of beautiful galaxy images on the internet, learn to recognise different types of
galaxy,and make a galaxy calendar (or web page, poster or card game).
(Also makes a good introduction to galaxies before doing the 'Galaxies Before the Dinosaurs'
project - about clusters of galaxies).




                                                 Barred spiral galaxy NGC 4725


                                                                           Outline

        What is a galaxy? .............................................................................................................. 2
        The challenge .................................................................................................................... 2
        Instructions ........................................................................................................................ 3
          1. Download images of galaxies from SDSS .......................................................................................3
          2. Practise classifying a few galaxies ...................................................................................................4
          3. Check with the experts .....................................................................................................................5
          4. Collect 12 images of different types of galaxy ..................................................................................6
          5. Showcase your collection of galaxies...............................................................................................6
          7. Please send us your evaluation! ......................................................................................................7
        Appendix: display options ............................................................................................... 7
          A galaxy calendar .....................................................................................................................................7
          How to make the galaxy calendar ............................................................................................................7
          A website ..................................................................................................................................................7
          A poster ....................................................................................................................................................7
          A card game .............................................................................................................................................8




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    Richard Beare, 24th November, 2008                            Version 1.60                                                      Page 1 of 8
AstroProjects                                                   Galaxy challenge
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What is a galaxy?

Galaxies are collections of millions upon millions of stars. They come in different shapes and
sizes. Some have beautiful spiral arms; others are virtually featureless. Some have bars across
the centre; others do not. The largest galaxies consist of hundreds of thousands of millions of
stars; the smallest only a few tens of millions. Some galaxies are actively forming new stars;
some finished doing this thousands of millions of years ago.




                             A selection of different types of galaxy

The challenge

      Find images of 12 different types of galaxy produced by the Sloan Digital Sky Survey
       (SDSS).
      Display these by making a galaxy calendar (or, if you prefer, a web page, poster, or card
       game).

Short of time? You could share the task of finding suitable galaxies with others and make your
galaxy calendar a joint effort.




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    Richard Beare, 24th November, 2008     Version 1.60                            Page 2 of 8
AstroProjects                                                   Galaxy challenge
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Instructions
1. Download images of galaxies from SDSS
Macintosh instructions are in square brackets [like this].

                                              a. Import the names and coordinates of galaxies into Excel
                                                    Click the link List of galaxies on the left hand side.
                                                   An Excel spreadsheet opens containing the names and
                                                   coordinates of thousands of galaxies in the RC3 Catalogue.
                                              b. Select and copy the galaxy data
Galaxy coordinates from RC3 Catalogue
                                                    As shown, the cells containing data should already be
                                                    selected. (If they aren't select them now – not the whole of
                                                    the three columns, just the data.)
                                                       Type Ctrl-C [Cmd-C] to copy the data.
                                              c.    Open the SDSS Image List Tool
                                                    Click the link to the Image List Tool on the left hand side.
                                                    This will open your web browser (e.g. Internet Explorer,
                                                    Firefox, Safari) and go to the SDSS Image List Tool.
  Where to paste the galaxy data in the       d. Paste the galaxy data into the Image List Tool
        SDSS Image List Tool
                                                    Click anywhere in the area shown by the red circle above
                                                    left, then type:
                                                       Ctrl-A [Cmd-A] (select all), followed by
                                                       Delete [Backspace] (delete existing data), followed by
                                                       Ctrl-V [Cmd-V] (paste).
                                              e. Download thumbnail images
                                                    Click the Get Image button.
                                              f.    Explore the images
                                                    You will now see thumbnails of the centres of 25 of the
Images of the centres of nearby galaxies            brightest galaxies.
as they first appear in the Image List Tool            Use the zoom control to zoom out until you can see the
                                                        whole of each galaxy.
                                                       Click on any thumbnail to see a magnified view in the
        The Image List zoom tool                        SDSS Navigate Tool. (On some computers you may
                                                        need to click the Get Image button in the Navigate
                                                        Tool).
                                                       You will need to use the zoom control again to zoom
                                                        out.
                                                       To look at a different galaxy, go back to the Image List
                                                        Tool window and click a different thumbnail.
                                                       To see different selections of thumbnails, click on one of
                                                        the page links at the top.
   The same galaxies as above after
        zooming out four steps




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    Richard Beare, 24th November, 2008             Version 1.60                                 Page 3 of 8
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2. Practise classifying a few galaxies
Spend some time looking through a few different types of galaxy, deciding, in discussion with your
partner, and with the help of the Hubble classification notes below, what sort of galaxy you think
each is. Once you have got the idea, go on to the next section and start checking your guesses
with what professional astronomers have decided.


Hubble's classification of galaxies
Below is a simple diagram of Edwin Hubble's 'tuning fork diagram' for classifying galaxies (first
published in 1936 in a book called The Realm of the Nebulae.) Compare these diagram with the
example galaxies given near the beginning of these instructions.
                                      lenticular              spiral      spiral           spiral




    elliptical       elliptical          S0                    Sa           Sb               Sc




       E0               E6        barred lenticular    barred spiral   barred spiral    barred spiral




    irregular                            SB0                  SBa          SBb              SBc




       Irr


Read 'Understanding Galaxies'
If you have enough time, now would be a good moment to read this background information
which can be downloaded via the Background science link. It explains more about the science of
galaxies - information that will enable you to include a brief scientific explanation alongside each
of your galaxy images.
However, if time is limited at present, just carry on with the project and come back later on to
learning more about galaxies.

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    Richard Beare, 24th November, 2008         Version 1.60                            Page 4 of 8
AstroProjects                                                   Galaxy challenge
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3. Check with the experts
Once you have got the idea, start checking your answers against what professional astronomers
have decided. (If you wish, you could do this as a sort of game, with each person in turn picking
a new galaxy and challenging the other person to classify it accurately.)


                                                 a. Look at images of a number of galaxies
                                                         Click an Image list thumbnail to get a large image in
                                                         the Navigate Tool. (On some computers you will
                                                         need to click Get Image to load the image.)
                                                        Decide what type of galaxy it is.

                                                 b. Get further info from SDSS
                                                        Click the small Explore link just under the SDSS
                                                         logo at the top left to take you to the SDSS Explore
  Spiral galaxy M109 in the Navigate Tool                Tool.

                                                 c. Go to the SIMBAD database in France
                                                        Click the SIMBAD link at bottom left.

                                                 d. Find out more information
                                                     SIMBAD will give the name of the galaxy, its
                                                     coordinates in the sky (RA and dec), its magnitude
                                                     using either blue or green filters (B or V), and what type
                                                     of galaxy it is.
                                                          HINT: If more than one galaxy is listed, the first one
                                                          will be the one at the centre of the image.
                                                          HINT: Galaxies usually have several names.
                                                          SIMBAD will give you the commonest name –
                                                          usually not the PGC name in the spreadsheet data.
 The Explore Tool showing the SIMBAD link            SIMBAD uses a slightly more sophisticated Hubble
                                                     classification than the one described above. Make the
                                                     following simplifications:
                                                        Sd and SBd refer to galaxies further along Hubble's
                                                         tuning fork than Sc and SBc - just count these as
                                                         Sc and SBc.
                                                        Sbc (with a small 'b') is midway between Sb and Sc
                                                         – you can count Sbc as either Sb or Sc. (Similarly,
                                                         count an SBbc barred spiral as either SBb or SBc.)
                                                        Sdm and Sm refer to galaxies similar to the Large
                                                         and Small Magellanic Clouds visible from the
                                                         Southern Hemisphere –count these as Irr (irregular
                                                         galaxies).

                                                 e. When you have finished practising
SIMBAD shows M109 to be a spiral galaxy of
    type SBb. S means 'spiral', B means          Carry on checking galaxy classifications until you think that
 'barred', and b indicates that the exact type   you generally agree fairly closely with SIMBAD.
               of barred spiral.




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     Richard Beare, 24th November, 2008          Version 1.60                                 Page 5 of 8
AstroProjects                                                   Galaxy challenge
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4. Collect 12 images of different types of galaxy
Now that you are reasonably confident at classifying galaxies, you need to choose 12 for your
display, one from each of the types in the following table. Don't forget that if you are short of time
you could make your galaxy calendar a joint effort, with different people each contributing a few
galaxy images.


  two elliptical galaxies (one nearly circular and one      E0 or E1   E5 or E6
  quite elongated, as judged by eye)
  four disc galaxies that are not edge-on (one                S0          Sa       Sb         Sc
  lenticular and three spirals)
  three barred spiral galaxies that are not edge-on                      SBa       SBb        SBc
  two edge-on spiral galaxies                                          Sa or SBa           Sc or SBc
  one irregular galaxy                                         Irr


You should choose examples that you like the look of and which you think make the different
types of galaxy clear. You will probably want to use some of the examples you have already
looked at, as well as finding new examples using the Image List Tool.



5. Showcase your collection of galaxies


a. Choose a display method
Select one of the following methods:
     a galaxy calendar that you can print off and give to friends and relatives
     a website that everyone can look at
     a poster that you can display at home or in school
     a set of cards for a game such as 'snap' that you can play with your friends
Hints on the different display methods are given in the Appendix at the end.

b. Write something about each galaxy
Whichever display method you choose, it would be good to include some scientific information
about each galaxy in your collection. For example, you might write the following about a
particular Sc spiral galaxy:
        There are blue spiral arms which contain newly formed, hot, bright blue stars. Just inside
        these arms there are dark dust lanes containing dust and hydrogen gas out of which new
        stars will form.
To find out more about different types of galaxies, read the background information
Understanding Galaxies, which you can download from the Galaxy Challenge web page.
Web space will be made available for you to put your display on the internet alongside the
displays created by others around the world (unless it is a poster), so building up an information
base about galaxies that any student, teacher or member of the public can look at and admire.



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    Richard Beare, 24th November, 2008       Version 1.60                               Page 6 of 8
AstroProjects                                                   Galaxy challenge
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7. Please send us your evaluation!
IMPORTANT When you have finished please fill in the evaluation - there is an Evaluation link on
the left hand side of the Galaxy Challenge web page. This will enable the AstroProjects team to
improve the project for the benefit of future students.

Thank you!

Appendix: display options

A galaxy calendar
Blank calendars for 2008, 2009 and 2010 can be downloaded from the Galaxy Challenge web
page. Each is an Excel workbook consisting of thirteen separate pages or 'sheets', one for the
cover and one for each month of the year.


How to make the galaxy calendar

   Download the appropriate blank calendar by clicking the Blank Calendars link on the left hand side of
    the Galaxy Challenge web page and then the correct year.
   IMPORTANT Before you add images and text to your calendar, you must save it somewhere on your
    computer. Give it a name that identifies it as your calendar to save confusion with other people's, e.g.
    'Galaxy calendar - Jill Smith'.


   Click the jan tab to select the January sheet.
   Click the Chart link (top left hand of the screen)
    to see the galaxy image in the SDSS Finding
    Chart tool.
   Right-click on the image [Ctrl-click on a Mac]
    and choose Copy.
   Paste the image onto the January page.
   Move and resize until the image is nicely
    centred with some white border around it.
   Enter the galaxy name and your brief scientific
    description where indicated.
   Close the Finding Chart window to return to the
    Image List tool.
   Repeat for the other eleven months.


A website
Web space will be created to enable you to showcase your work on the internet. The project
team will maintain an up to date list of galaxies that people have already looked at and displayed
on the internet, so that you can choose different ones so that your contribution will be original to
you.


A poster
A poster is not easy to post on the internet, but it does have the advantage that it can be
displayed in school or at home for others to look at.
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    Richard Beare, 24th November, 2008           Version 1.60                                Page 7 of 8
AstroProjects                                                   Galaxy challenge
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As astronomical images generally have a black background they look most natural mounted on
black poster paper if you can get hold of it.


A card game
Snap
You could make cards for the well known card game 'snap'. You need four cards for each of the
different classifications given above in the table on page 5. Each should be contain a galaxy
image and be labelled. For example, there would be four cards labelled E0/E1 with images of E0
or E1 galaxies, four labelled Sa with images of Sa galaxies, and so on. Not all the images of one
type need be different.
This game of snap is played in the usual way. In brief this is as follows. The object of the game
is for one player to collect all the cards. Start by distributing all the cards as evenly as possible
between the players, face down in piles. Each player in turn turns over their top card on their
face-down pile and places it in a face-up pile alongside. Everyone looks to see if the card just
turned over has the same classification (e.g. E0/E1 or Sa) as one already on the top of someone
else's face-up pile. If this is the case, the first person to call snap, (and this is the additional
twist!), has to say something scientific about that particular type of galaxy. Provided they can do
this, they take both of the face-up piles whose top cards match, and add them face-down to their
own face-down pile. The winner is the first person to collect all the cards.
Instead of snap, you might like to invent your own card game that could be played using galaxy
cards of some sort.

Acknowledgements
I am grateful to PPARC, the Particle Physics and Astronomy Research Council, (now part of the
Science and Technology Facilities Council), for the Large Award for the Public Understanding of
Science, that enabled this activity to be developed.
I am also grateful to Professor Michael Merrifield of Nottingham University for carefully reading
through these project materials and making valuable suggestions. Any responsibility for
inaccuracies, however, remains mine.
I also wish to thank Janet Hilton of Kingsley School, Leamington Spa, David Chesterman of Saint
Peter's School, Solihull, and their students, for their very valuable input to this activity during its
pilot phase.

Richard Beare, Institute of Education, University of Warwick. 4th March, 2008




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    Richard Beare, 24th November, 2008       Version 1.60                              Page 8 of 8

				
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