Background Information - Measuring Sizes
Measuring distance across the widest part of crater
- Display your observation of part of the moon.
- Choose a crater.
- Select ASTRO (menu) and then SIZE & DISTANCE (option)
- Carefully click and drag the pointer from one side of the crater to the other.
As you do this a right angled triangle is created. The hypoteneuse is the distance you are measuring across the crater in pixels, and the value in pixels is displayed to the right of the image.
Pixels are NOT a measure of distance.
You now have to convert total size (pixels) into Kilometres to find the size of the crater.
The number of kilometres represented by ONE PIXEL must now be found.
This can be done by clicking on ASTRO (menu), IMAGE PROPERTIES (option) and then CALIBRATION (button on right). You will see Pixel scale (at the object) displayed with a value for this observation.
Multiply the pixel scale by the number of pixels across the crater and you will have a value for distance in kilometres.
