This lab exercise is intended to provide you with insight into major lunar features as well as an understanding of the sizes of these features. You will asked to examine a number of lunar images - these will be available in both paper form (to include as part of your report) as well as in electronic form for analysis using on-line tools. This is the first part of two lab exercises that make up your third major lab of the term.

Materials and Resources

  • access to Stellarium
  • access the applet Lunar Scale Calculator
  • an image manipulation program (Microsoft Paint on PCs or GIMP on Macs are good choices)
  • paper copies of lunar images from The King's University Observatory


  1. Please select images from each of the two following sets. Choose 1 image from each set and be sure to note the image scale that is shown in the table below. When the image is displayed "right-mouse-click" on the image and save it to your local hard drive (make sure you note which directory it is being saved in!) - it would be a good idea to save it into your "My Documents" folder .
Image Set Image Info Image
A Image A1: Centred on Copernicus crater. Image taken evening Nov 5, 2011. Image scale is 0.24"/px
  Image A2: Centred on Eratosthenes crater. Image taken evening Nov 5, 2011. Image scale is 0.24"/px
  Image A3: Centred on Archimedes crater. Image taken evening Nov 5, 2011. Image scale is 0.31"/px
  Image A4: Capuanus crater in lower left. Image taken evening Dec 26, 2009. Image scale is 0.20"/px
B Image B1: Kepler crater with Copernicus in the upper right. Image taken evening Feb 4, 2012. Image scale is 0.52"/px
  Image B2: Tycho crater in the upper left. Image taken evening Feb 4, 2012. Image scale is 0.52"/px
  Image B3: The Apennines Mountain chain with Eratosthenes near centre of image. Image taken evening Mar 1, 2012. Image scale is 0.52"/px
  1. Open your favourite image analysis program as well as Lunar Scale Calculator. You will need these applets to help analyze your lunar images. In this example we will use Microsoft "Paint" which is part of any Windows system. If you are using a Mac then GIMP is a good choice. All you need to be able to do is to draw a straight line on the image that you are investigating and get from this the " X length " and " Y length" for the line.
  2. Use Paint (or similar program) to open one of the images that you have saved in your "My Documents" folder


  1. Be sure to look up the distance between the earth and moon for the night on which each image that you choose was taken. Use Stellarium to do this. The distance will be given in AU but you can use the applet Lunar Scale Calculator to enter the distance in AU. You will also need to enter the scale of the image in seconds or arc per pixel ("/px). Finally, enter the X and Y lengths of the feature in pixels and press the calculate size button.

    In the example on the right the scale was 0.24 "/px, the moon was 0.00252233 AU away and the lunar feature you were interested in measured 91 pixels in X and 104 pixel in Y or a length of 123.05 pixels (the applet does this calculation for you!). This implies its actual size is 60.67 km. Since your scale is really only accurate to 2 digits you should round this to 2 digits and record the final length as 61 km.


For each of the images that you chose please do the following:

  1. Prepare a table in which identify by letter or number at least 5 features on each of the two images that you wish to measure. Carefully note this on the hard copy (which will handed in along with the report) as well as in the table. Be sure to record the image scale and the size of the feature in both pixels and kms.
Image Name
scale = ("/px), Distance (AU)
Feature Size (px) Size (km)


  1. For each image discuss evidence that you have for such things as:
    • craters formed at different times on the moon
    • some impacts produced breccias resulting in lunar rays
    • the range in sizes of craters
    • existence of lunar rilles and other features such as lava flood plains
  2. Discuss what each image tells you about the history of the moon. How do you know that lunar bombardment has occurred over a very long period of time on the moon? Is it still happening today?

What to Hand in and When

This lab project is due in 3 weeks. This will be combined with a similar project in two weeks time on measuring planetary features. The exercise will be graded as follows:

Neatness and format:

  • Useful headings
  • grammar and spelling
  • typed and followed format

Discussion of Data

  • number of features discussed
  • insight into the features and what they mean
  • variety of lunar features that you investigated


  • what insights about lunar and planetary origins does your data suggest - spend some time discussing what you have discovered and suggest other things that the data may tell us.


Be sure to use a formal report style (separate cover page and proper use of headings and table/figure annotations).