#5 Crater Hopping on the Moon

I just got back from a Meet-up of the Reno Suburban Sky Explorers with our fantastic host, Richard Smith (his blog is under the link).  The meetup was at his house where Richard had a great setup and view of the moon.  The focus of the meetup was our old friend Luna who is at quarter-phase (46.9%) right now and at a distance of 371,494.2 km (230,835.8 miles).  Oh, since people in this country only understand distance measurements in terms of football fields, the distance to the moon tonight was equal to 135,423,669 football fields (damn History Channel).

I started the lunar observe by just taking in the moon and getting my bearings straight.  We started at 5:00 pm PST so there was still plenty of light.  Richard's 8" reflector worked great, however.  The tracking was set up well and I only needed to make minor corrections to keep the area I wanted to look at in the center of the viewing window.

To aid in my lunar navigation I was using the Moon Globe HD iPad app.  The app works really well.  You can adjust the orientation of the moon to reflect what you are seeing through the telescope.  For example, the reflector, like all reflectors, reversed the image so west was east and east was west.  No problem with Moon Globe HD.  I'm also able to change the time thereby changing the shadows that I'm seeing on certain craters and giving me a heads up as to what I'll be able to see in a few hours.  I highly recommend the app.

From Moon Globe HDSo, once I got oriented and re-familiarized myself with the lunar landscape I started to check out the craters on the terminator.  The first place that drew my eye was the crater Archimedes in the eastern half of Mare Imbrium.  Archimedes is an 82 km (50.95 miles) diameter crater with nice high walls that reflect the sun as it starts to rise.  Incidentally, Archimedes is named for the Greek physicist and mathematician of the same name that lived from c. 287-212 BCE.  Archimedes was putting on quite a show with the light shining off the eastern rim.  Just north of there the Spitzbergen Mountains were starting to light up.

The Spitzbergens are a short mountain range at only 1.4 km (4,593 ft) high.  However, since the range is made of a rugged material with smooth slopes and a high albedo (whiteness) the stand out really well when the sun hits them.  Fantastic!


From Moon Globe HD

One crater that I kept going back to all night, besides Archimedes, was Ptolemaeus.  Ptolemaeus, named for Claudius Ptolemy, a Greek astronomer, mathematician, and philosopher (c. 87-150), is a great orientation crater since it is positioned near the lunar equator (about 9o south) and really easy to see.  The crater is 158.3 km (98.4 miles) in diameter and has high walls that reflect the rising sun quite nicely.  As Ptolemaeus started to come into view the rims and center cones of Alphonsus and Arzachel shined brightly.  They are just south of Ptolemaeus.

Over the course of the evening my eye wandered over to the lunar Apennines (Montes Apenninus), the Sea of Vapors (Mare Vaporum), and the Sea of Serenity (Mare Serenitatis).  The highlights of the Apennines as the sun was rising were fascinating.  Sometimes we forget that the moon is an entire other world just circling around ours.  There is so much to explore.  On the Sea of Serenity is a crater called Bessel.  Just west of the Bessel crater is the "Bessel Ray".  Bessel is the well-defined crater. The "ray" is the lighter area just to the right of it, west in this orientation.It is a slightly-difficult-to-see light gray ray that is radiating from the south southwest.  It is thought that the ray is from the creation of the crater Tycho, nearly 2000 km (1,243 miles) away!

From Moon Globe HDI ended the night by studying the southern portion of the moon that periodically wobbles to a more oblique angle and becomes harder to see.  I was looking in the region of the Stӧfler Crater, named for the German astronomer and mathematician of the same name (1452-1531), when I noticed a small point of light on an unknown (to me) crater to the west.  I navigated my way from Stӧfler to Miller and Nasireddin just to the west.  Nasireddin overlays the eastern edge of Huggins with overlays the eastern edge of Orontius.  I believe it was the western edge of Orontius that I saw the pin point of light on.  Tomorrow night I might be able to see more of it.  Between Miller and Nasireddin I saw a dark shadow that looked like, to me, an indication of a very tall peak between the craters.  There is sloughing of material on the northern and eastern sides of the peak.  Richard seemed to agree that it could be a tall peak.  It sure was casting a large shadow.

One more observation I made involved the crater Plato in the north.  A couple months ago we observed the moon and Plato was a landmark crater that we used to orient and navigate from.  Tonight, however, Plato was at an extremely oblique angle and difficult to see.  This is due to a phenomenon called Lunar Libration.  Libration refers to the oscillating motion of two orbiting bodies relative to each other.  That means that the northern and southern poles of the moon reveal and take away breathtaking views every day.  Pretty cool.  There is always something new to see between the lunar libration cycle and the steady waxing and waning of the terminator.Lunar Libration. From Wikipedia

I've certainly left out some of the things that I saw tonight.  There was just so much.  The moon is a fascinating place and it's easy to look at with a low powered telescope in a suburb of a major city.  You don't even need a telescope, really.  A good pair of binoculars would suffice.  Thank you to Richard Smith and his tireless efforts in teaching astronomy to the general public.  If only more people new just how easy it is to navigate your way around another astronomical body and that there are entire worlds just waiting for us to explore.