Measuring Impact Craters on Earth

Crater Google Earth Example In this activity, Google Earth will be used to observe and measure some real impact craters on the surface of the Earth. These craters vary in size from small (a few hundred meters) to very large (over 100km).

In this activity you will be measuring craters of different sizes on Earth which are the result of an impact from space. The impacts causing these craters would result in a variety of climatic changes - small impacts would generally affect only the local area, whereas larger impacts could have massive changes in the global weather systems.

To begin, download Google Earth, then follow the instructions below.

Finding and measuring impact craters

In order to find the impact craters that you will be measuring for this activity, you will have to enter the latitude and longitude of the craters into the ‘Fly To' box in Google Earth. Once you have found a crater, you can save it’s position in so you don’t have to enter it’s co-ordinates every time you want to view it.
In the lat/long boxes, enter the co-ordinates of the place you wish to view. For example, to view the Barringer Meteor Crater click in the ‘Fly to’ box and enter 35 02 N, 111 01 W
Google Earth will automatically fly across the Earth to the co-ordinates that you have sent it to. You can then add a placemark on your map by going to the main Google Earth menu at the top of the screen and clicking on Add > Placemark, or by clicking the symbol at the top of the window. A pin symbol in a yellow box will then appear on your map which you can move to the centre of your crater by dragging it with the mouse. Once positioned, you can enter its name in the pop-up box which has appeared, and this object will then be saved in your Google Earth folder under ‘My Places’.
To measure the craters listed in the table below, you will use the Measure tool in Google Earth. To find this in the main Google Earth menu, click on Tools > Measure . Or, click on the symbol at the top of the window. A pop up box will appear in which ‘line’ is already selected. Click on the units box to select km. You can now measure the diameter of each impact crater in Google Earth by using the left button of the mouse and dragging the line across the width of the crater. The distance measured is shown in the pop-up box.

Impact craters

Find the following impact craters using Google Earth, pinpoint them and measure their largest diameter (some of the craters are elliptical in shape, not round).

Crater Name	Latitude	Longitude	Size (km)
Barringer Meteor Crater This meteor crater was formed about 50,000 years ago by an iron meteorite impact and is very easy to find in Google Earth.	35 02 N	111 01 W
Manicouagan This impact crater is one of the oldest known craters on Earth. It was formed about 200 million years ago, and although some of the crater has been worn away by erosion, it is still very clear and easy to find in Google Earth.	51 23 N	68 42 W
Clearwater Lakes These 2 impact craters were formed by a pair of asteroids hitting the Earth’s surface. In one of the craters, a circular area of islands can clearly be seen. This is an elevated part of the crater, as seen in a complex crater. The central part of the second crater cannot be seen however as it is below the water.	56 13 N	74 30 W
Upheaval Dome Originally thought to be a collapsed salt dome, this crater has all the features of a typical impact crater - a central peak, an inner crater and outer concentric shock rings. This makes it easy to identify in Google Earth.	38 26 N	109 54 W
Rio Cuarto The depressions in the land at Rio Cuarto do not look like typical impact craters. They are elliptical in shape, suggesting that they formed as a result of a group of very low angle impactors ‘scratching’ the ground as they came down. However, there is some doubt of the validity of these scars as impact craters, with some scientists believing that they are nothing more than features formed by winds on the Earth’s surface.	32 52 S	64 14 W
Gosses Bluff This impact crater in Australia is believed to have been formed over 140 million years ago. The central raised ring is not the rim of the crater - this lies much further out.	23 50 S	132 19 E
Tenoumer This crater in Africa actually lines up with two other craters in the region. It is easy to identify in Google Earth - once located, try finding the larger crater to the South West.	22 55 N	10 24 W
Vredefort This impact crater has a multiple ring structure which can be seen by zooming out of the town of Vredefort in Google Earth.	27 00 S	27 30 E

Comparison with local distances

Once the size of each impact crater has been determined in Google Earth, a comparison can be made with distances local to your school or home. This will give a some perspective on the sizes of these objects.
Enter the street name or postcode of your school/home in the ‘Fly to’ box in Google Earth.
Once Google Earth has flown to your location, choose the measure tool once again.
Using the mouse, left click on your location to mark the point where you would like your line to be drawn from. Make sure your units are in ‘kilometres’ again so you can make a proper comparison with the impact craters.
Zoom out of your location in Google Earth so that you can fit a line the size of one of the impact craters, onto your map.
Click on the green box at the end of your drawn line to extend the length of the line.
Finally, extend your line until its length equals the size determined for each impact crater previously. This puts into perspective how big the impact craters really are!