Visual measurement of the distance the terminator advances over exactly 24 hours time. These two images were captured exactly 24 hours apart. The image to the right, taken August 4th and the other August 5th 2011, during waxing Moon. The upper crater in the cluster with central peak is Theophilus. (approximately 68 miles in diameter and 2.5 miles deep. It's multiple central peaks reach upwards of 18,000 feet). The terminator advances just over 12 degrees per Earth day, approximately 200 miles. The small red circle to the Northwest of Theophilus approximately marks the Apollo 16 landing site. Some Lunar samples returned by Apollo 16 are believed to be ejecta from Theophilus.
Astro-images taken through a telescope on a tracking mount provide breathtaking color and detail that you just can't see with your eyes alone. The astro-images on our web site demonstrate the imaging capabilities of the products used and are not intended to represent what you will see when you look through a telescope. Learn More