Explore the Universe - Clavius

The final crater I observed on May 4, 2017 is called Clavius.  This has become one of my favourite craters due to its distinctive pattern.  There are a set of craters inside Clavius arranged in a half-circle with progressively smaller diameters.

Clavius

Clavius' diameter is a colossal 225km which is approximately the distance between Calgary and Cardston.  It is also one of the oldest craters dating back nearly 4 billion years.  The diminishing craters inside Clavius have diameters (50, 28, 21, 13, 12, 8)km.  These craters are well known for being a test of a telescope's resolution.  How many of these craters can you see?

Clavius is named after the German astronomer named Christopher Clavius.  He was a strict adherent to the geocentric view of the universe with the Earth at the center.  However, this did not let him get in the way of a great friendship with Galileo.  Clavius is probably best known as one of the architects of the Gregorian Calendar.  The Gregorian Calendar replaced the Julian Calendar throughout civil society beginning in 1582.  It is worth noting that some countries have yet to accept the Gregorian Calendar.  The Julian Calendar is still used by some Orthodox Churches most notably the Russian Orthodox Church.  The last country to use it was Greece until they switched over in 1923.

A wide field image of Clavius shows how close it is to the more famous Tycho.  The large crater between the two is known as Longomontanus who was Tycho Brahe's assistant in Denmark.  The crater on the Northeast rim is known as Porter or Clavius B.  The first of the diminishing craters is called Rutherfurd after an American astronomer famous for his Sun and Moon photography.  The central peaks in Rutherfurd seem to look like eyes in the image below.

Clavius Wide Field

Enjoy the sight of the Moon and take a closer look to see if you can see any remarkable features on its surface!