10 Days old Moon (April 04, 2020) – Benoit Guertin

The photo above is of a 10-day old Moon taken a few days ago. After the darker “seas” of old lava flow, one particularly bright crater in the southern hemisphere stands out, especially with the rays that appear to emanate from it. That is Tycho, a 85km wide and 5km deep crater and one of the more “recent” ones if you consider 109 million years the not-to-distant past. The Moon is 4.5 billion years old after all… having formed just 60 million years after the solar system. On the Moon, “fresh” material have a higher albedo and hence appear brighter, whiter.

The bright rays surrounding Tycho are made of material ejected (up to 1500km away) from the impact of a 8-10km wide body. In time these rays will disappear as the Moon continues to be bombarded by micro meteorites, which stirs the material on the surface. The rays are more present on the eastern side, as would be expected from a oblique impact.

Tycho is names after the Danish astronomer Tycho Brahe.

The Surveyor 7 space craft landed about 25km north of the crater on January 10, 1968.

Ever wondered how mosaic space photos were done before the invention of powerful software algorithm to stitch them together?  Take a look at the series of Surveyor 7 mosaic photos.  Someone had to painfully print each photo and lay them on a grid in a specific pattern matching optical field and geometry.