I first wrote this blog back in September 2016. This is a slightly updated version and now included in the Go Observe series.
Go Observe Reiner Gamma
Every time I seek to do a sketch of the lunar surface, there has to be a visual trigger to set me off. On this particular night, I was offered one of the clearest steadiest views I have had for a long time. Reiner Gamma, that little bright kite shape on the lunar surface inspired me to draw. Before I start a drawing I observe the target and the area around it for some time. This helps me spot the bright areas , dark areas and their shapes as they appear to my eye.
For my moon sketches, I use pastel thickly, sometimes several applications on top of the other. This is deliberate as I can then use specific instruments to almost carve out shapes and liner features. The seeing was good, so I could use a 2 X Barlow to increase the magnification and my chances for observing detail. Using a Barlow of any kind is rare in Ireland as the atmosphere is often shaky. Increasing power also magnifies any aberrations in the atmosphere and can frustrate the effort.
At 97.2% illumination of the moon, only a fraction of terminator is left to deal with. Nearly always the best contrast targets are showcased on the terminator, which is the demarcation line between day and night on the moon. However, an albedo feature like Reiner Gamma stands out all by itself against the grey lunar surface and is interesting for that alone.
In my moon sketching box, I have some scraping tools, like for metal etching. They are not as tiny as I would like them to be, plus they are also sharp, not ideal for use on a paper surface. However one similar to a needle was suitable for making the fine edges on the ridged outer walls of Hevelius and for that long rille which I observed to run through Oceanus Procellarum into and it seemed out of the little kite. The linear marking out of Renier Gamma seemed different and appeared to have similar bright material within it.
I first drew in Renier to give me the position of Reiner Gamma. I kept an eye on the Lohrmann, Hevelius, Cavalerius trio. Dark shadows ran from them as the suns increasing light presented them in a new form. They were irresistible, so I moved on to draw their shapes and enjoyed their rich contrast. Over the years, I have learnt to work on features in several places within the field of view. Rotating your time between elements helps to keep your drawing balanced and also helps keep things in correct proportion to each other.
Lohrman A and Herman were drawn. Next, these craters gave me a kickoff point to sketch in that long line that sweeps up past Reiner Gamma and toward Marius. Reiner Gamma seemed flat, even though the central region appeared a little duller than its edges which seemed to glow slightly.
Afterwards, I was pleased to notice that I had sketched in crater Galilei. A tiny dent in the lunar surface honours an astronomer who paved the way for lunar understanding monumentally. Nearby Aristarchus and Vallis Schroter looked incredible as the seeing improved and the time ticked by towards local midnight.
Learning by Drawing
Reading about Renier Gamma sometime later I discovered it is known as a lunar swirl. An unusual feature of bright regolith, a real anomaly with magnetic fields. There is a lot written about swirls but no definitive answers as yet to their origins.
Often I draw first and ask questions later stimulated to learn by my observations. I use Virtual Moon Atlas, which is a free software to identify features in my drawings. You can become very familiar with the moon by accessing the data within VMA. You can become even more fully aware by making attempts to draw our nearest neighbour. Here is the link: Virtual Moon Atlas
Fellow blogger Christopher Graney wrote an interesting piece on how drawing precisely what you see is valuable.