Lunar Shadow Speed

With the help of a partner, estimate how fast the shadow of the moon travels across the ground. Can you out-race it in a car? In a jet plane? The answer will surprise you!

Method 1:

Step 1: What time was it to the nearest second when the full total eclipse started? This would be the time when the landscape around you began to darken

Step 2: What time was it when totality ended and the landscape started to brighten quickly?

Step 3: Take the difference in these times to get the time it took the lunar shadow to pass over your location.

Step 4: Convert your time into decimal hours.

Step 5: The average diameter of the shadow spot is 110 kilometers. Divide your time answer in hours into 110 km to get the shadow speed in kilometers/hour.

Method 2:

Partner with someone located a few hundred kilometers away and share your information via a text message. You will also need to use the GPS feature on your phone to determine your latitude and longitude to be shared with your partner.

Step 1: Use your iPhone GPS App or a map to determine your geographic location in latitude and longitude. Convert to decimal degrees by dividing the minutes by 60 and the seconds by 3600 and adding the resulting two decimals to the degree value. Round your answer to two decimal places.


Thumbnail Image Credit: MIR Cosmonauts

National Aeronautics and Space Administration