# Measuring Impact Craters on Mars

The first step in this activity is to change the view in Google Earth, to Mars.

• This can be done by going to View >Explore >Mars or by clicking thesymbol and choosing 'Mars'.

Finding impact craters

In order to find craters in Google Mars, you can search for a particular crater using the 'Fly To' box, together with the name of the crater, or its coordinates.  You can zoom in or out of the image by using the controls, and you can drag the image by using either the controls or your mouse.

To help familiarise yourself with Google Mars, try the following exercise:

• In the 'Fly To' box, enter the coordinates: 49.8S, 4.6W. You will now fly to this location which is the site of an impact crater on Mars, named 'Roddenberry crater' after the creator of Star Trek, Gene Roddenberry.
• How many other craters can you see on top of the Roddenberry crater?
• Using the measure tool , measure the diameter of the Rodenberry crater
• Now find the position of the ‘Bond’ crater on Mars by using the 'Fly To' box. Zoom in on this area once it has been pinpointed.
• Using the measure tool , measure the diameter of the Bond crater
• In the 'Fly To' box, enter the name Orcus Patera. What do you think could have caused a crater this shape?
• In the 'Fly To' box, enter the coordinates: 14.6S, 82.9W. This crater is called the 'Odd Crater'. Zoom in on this crater- why do you think it has this name?

Comparing Mars craters with Earth craters

Zoom in/out of Google Mars until your window is filled with a Google Mars image.  Look at the distribution of impact craters in this image and answer the following questions:

• How does it compare to a similar image on Google Earth? Are there similar numbers of craters?
• What factors would affect the number of craters that we can see both on Mars and Earth?
• What other features can be seen on the surface of Mars?
• Do you see any evidence for plate tectonics on Mars?
• Do you see any evidence for water on Mars?