BAA Lunar Section
Dedicated to amateur research and observation of the Moon
The
art of drawing the Moon
By
Andrew Johnson
Based upon an
article Originally published in 'The Strolling Astronomer', Vol. 37
No.1, May 1993.
Contents
Introduction
Why make
drawings of the Moon?
Telescopic equipment
Preparation
Making the observation
Finished
drawing methods
References
This article
addresses the problems usually encountered by the beginning visual
lunar observer. It discusses drawing equipment, paper selection,
telescopic observation, drawing techniques, and producing finished
drawings. The article is intended to encourage beginning lunar
observers who wish to record what they see in the form of drawings,
and to gain a deeper understanding of an increasingly neglected field
of observational astronomy.
Introduction
The Moon is the
first telescopic target for most amateur astronomers. Undoubtedly few
of them were unimpressed by what they saw. However, it is
increasingly often that these first impressions fail to develop into
a long-term interest in the Moon. Why is this? One of the most
often-cited reasons is that since the Apollo missions there is
nothing more to be learned from Earth based observation, at least by
amateurs. In this respect, the current low level of interest in the
Moon parallels that during the period after Beer and Mädler's
publication of 'Der Mond' in 1837.
Why make
drawings of the Moon?
Drawing the Moon
introduces the observer to, and familiarizes him with, this stark
world, ever changing in appearance, as no other method can. You never
fully develop this one-to-one relationship with the Moon through the
study of books or photographs. Seeing this wonderful landscape for
yourself is as close as is possible to first-hand experience of our subject.
In this age of
CCDs some observers wonder why others still bother making drawings.
The answer is simple: We observe as we do because we enjoy it! This
reason is often overlooked or forgotten. Rather than to try to assign
scientific merit to my chosen method of making drawings, I justify
this approach on the basis of history, heritage, and individuality.
It is only natural
that observers wish to use the best equipment and the latest
technology in pursing their interest. However, in our headlong dash
toward technology, are we not in danger of ignoring the real
objective? I consider this last to be to develop a full understanding
and enjoyment of astronomy. Were we all to adopt tunnel vision, or
more topically CCD vision, then we could lose sight of all the other
aspects of our study which are highlighted by other methods of observation.
Also, what are we
to make of the work of our predecessors? You cannot interpret the
observations of Schröter, Beer and Mädler, or Elger, in
terms of the CCD images of today. If you try, all you will conclude
is that they often made inaccurate observations. To understand their
work, one needs to be a contemporary observer who is still practicing
the old methods.
Technology is
progressing at a quickening pace. Visual observers were at the
cutting edge of observational astronomy for some three hundred years.
Photography held that position for a century. It is my guess that
CCDs will last considerably less than that. However, when CCDs are
finally classified as obsolete, I hope that not everyone will abandon
them. If with every new technological advance we abandon all that has
gone before, then we lose touch with our past, and hence with our
history and the heritage of our predecessors' work. The result would
be that our common interest is much poorer. Also, we must not forget
individuality. It is astronomers, and their interpretations of what
they find, that add flesh to the science. On its own the pure science
of astronomy is cold, and less captivating than some of us might suppose.
Telescopic equipment
There has been
much discussion of this subject in recent issues of this Journal
[3,4], so I will not dwell long on this subject. My overriding
concern is to encourage more observers to draw the Moon. Thus the
only appropriate suggestion about telescopes is: "Whatever you
have, use it!" The ideal situation would be for all of us to
have the telescopes of our dreams. However, in reality most of us
have to compromise on the basis of portability, storage space, ease
of use; or, more likely, cost. More often than not, those promoting
the virtues of a particular form of telescope are defending the
telescope that they already have, by which they hope to reassure
themselves that they made the right choice when they parted with
their hard-earned money.
Many people with
small telescopes think that they cannot contribute useful work in
observing programs unless they own some computerized all-resolving
monster of a light bucket! This is simply not the case the majority
of the time, especially where the Moon is concerned; and it is well
to remember the small telescopes successfully used by the early
selenographers. What those pioneers might have given to have one. of
those telescopes that now lie idle on clear moonlit nights! Remember,
more often than not it is the skill, determination, and enthusiasm of
the observer that determine how useful a given set of observations
is, rather than the equipment used.
Preparation
Before going to
the telescope to make a drawing of a lunar region, spend some time in
preparation, so as to get the most out of the time spent at the
eyepiece. First, you should know in advance what you are going to
observe. There is nothing worse than trying when at the telescope to
decide what feature to draw. This is time-consuming and wasteful of
your concentration, energy, and enthusiasm, and of those all-too-rare
observing opportunities.
Once you have set
an observing goal, the next step is to prepare for making a drawing
at the telescope. For this you will need certain items: a clipboard
and clips, a source of illumination; drawing supplies, such as good
quality copier paper and pencils. Although they are not strictly
necessary for making the drawing, it will help to have a copy of the
Eiger Intensity Scale and a fairly detailed outline map of the Moon.
Most of us have
our own preferred ways of equipping ourselves, so we will discuss
this topic only briefly. The nature of the source of illumination is
not so critical as it is for deep sky observation. You can use
something more substantial than a tiny red LED because you are not
too concerned about ruining your dark adaptation when you are
observing the Moon! A small flashlight attached to your clipboard
will do. As for the paper, we now simply note that it will have to be
thick enough so that, when the humidity is high, it will not wrinkle
due to moisture while the drawing is being made. Pencils of various
grades can be used, such as HB and B. The harder grades are less
suitable because the marks that they make will be hard to see under
dim lighting conditions.
The Elger
Intensity Scale is a method of gauging the intensity of light and
shade on the lunar surface. This numerical intensity scale was
actually introduced by Schröter and was later elaborated by
Eiger. In many ways it parallels the intensity scale used by
planetary observers-The Eiger Scale runs from 0 through 10, with 0
being black shadows and 10 the brightest feature normally seen on the
Moon, usually taken as the sunlit central peak of Aristarchus. This
scale can be calibrated by reference to well-known lunar features.
0 — Black: the darkest lunar shadows.
1 — Very dark greyish black: dark features under extremely shallow illumination.
2 — Dark grey: the southern half of Grimaldi's floor.
3 — Medium grey: the northern half of Grimaldi's floor.
4 — Medium light grey: general tone of area west of Proclus.
5 — Pure light grey: general tone of Archimedes' floor.
6 — Light whitish grey: the ray system of Copernicus.
7 — Greyish white: the ray system of Kepler.
8 — Pure white: the southern floor of Copernicus.
9 — Glittering white: Tycho's rim.
10 — Brilliant white: the bright central peak of Aristarchus.
If you are
unfamiliar with the locations of the standard features used for
Elger's Scale, it will help to have a simple outline map of the Moon,
with the relevant features prominently marked on it. You can paste
both the verbal description of the scale and the reference map to
each side of a piece of cardboard, covering them in clear plastic for
use at the telescope.
The simple outline
map just described should be adequate for identifying features. I
would not take anything more detailed to the telescope so as to
ensure that my observations are objective and unbiased.
Making the observation
Upon commencing an
observation, it is best not to start drawing right away. It will pay
dividends later if you spend some time studying your subject through
the eyepiece, familiarizing yourself with some of its details.
One important
consideration is the scale you will use for your drawing. In my very
first drawing of the Moon, I represented the crater Clavius, 225 km
in diameter, by an oval only 50 mm across! Needless to say, it was
not a great observation. The question of scale has as much to do with
convenience as with anything else. It is hard on a small drawing to
fit in all the details visible. Drawings that are too large, however,
are daunting and difficult to place detail upon. There are no set
rules, so experiment to determine the drawing scale that is best for
you. If you find that the details on your drawing are cramped, of if
you are having problems with proportions, then the first thing to
check is what scale you are using. However, as you can see from the
foreshortening evident in the figures, any scale you adopt can only
be approximate.
When you are
finally prepared to make your drawing, the question is where to
start. Before drawing, study the shape of the crater or other
formation you intend to draw. A common mistake of beginners is to
assume that all craters are circular, at least as seen from directly
above. This is definitely wrong; you will be hard pressed to find a
circular crater larger than 30 km in diameter anywhere on the Moon.
Most larger craters are actually polygonal, so study their sides: How
many are there, are they of the same length, are they straight or are
they curved?
Also remember the
effects of foreshortening. The classic example of this is Mare
Crisium, which is actually elongated east-west. However, as seen from
Earth, it appears elongated north-south. Most of the features you
observe will be elongated. In drawing them, decide what ratio best
describes the proportion of their apparent major and minor axes; for
example, is it 2:3 or 3:4? This proportional way of considering a
feature to be drawn is quite useful, especially in the placement of
minor details.
Very frequently,
the observer will draw a crater, such as is illustrated in the
figures with this article. For this reason we will now concentrate on
drawing craters.
Once the shape and
outline of the crater have been considered, we can turn to its
details. Again, two separate aspects have to be considered; the
actual features on the Moon, and the appearance of these features due
to the effects of light and shade. The study of minor detail can
become very absorbing, so be careful not to study one little area too
long. The purpose of the initial scrutiny is simply to prepare
yourself for making the drawing. Ask yourself what details are
visible; whether there are craterlets, hills, scarps, or rilles. Then
look at the shadows and bright areas. Consider how the shapes of
these tonal areas are affected by the actual relief, and what is the
nature of the relief that can produce such a pattern. Build up your
initial study along these lines, and only then start to think in
terms of putting this information down on paper.
Figure 1 (above)
shows the creation of the main outline and the major shadows. Some
construction lines are shown to reinforce the concept that crater
walls need not be circular, or even curved. At this stage, draw the
outlines of the crater walls and shadow areas slightly heavier than
any other lines. Once the main shadow outline has been delineated, it
is important not to alter it because shadows are the visible features
that are most likely to change during the observation. Subtle changes
in the tones of other areas will occur as the solar angle changes,
but these changes are nothing like so important as the changes in the
shadow outlines. These last can occur in less than a half hour,
especially when near the terminator. No really useful observation is
likely to be completed in less time than this, so the early fixing of
shadow outlines is necessary. As the next step, start filling in the
major details as shown in Figure 2 (above).
Such details
include inner-wall terraces, large craterlets, and similar features.
The best way to determine these objects' positions and proportions is
to establish their sizes and positions in terms of fractions of the
dimensions of the main crater. You can do this mentally by dividing
up the crater into fractions; such as quarters sixths, eighths, or
whatever proportions suit you. You can also follow this procedure for
minor de tails, using the sizes of features to determine their
positions in terms of their own diameters. Follow this procedure for
all the features that you can definitely see, working from the
largest to the smallest, constantly checking that you are maintaining
correct positions and pro portions. Your drawing should be almost
complete by now as far as linework is concerned.
You should not
attempt shading at the eyepiece, but you can add it later instead if
you make annotations on the drawing concerning the levels of light
and shade. This is best done using the Eiger Scale. However, if as a
beginner you are not confident about its use, then just jot down some
notes about which areas were darkest and which were lightest. As your
experience grows, you will find a need for refinements such as the
Elger Scale.
Figure 3 (above)
shows the nearly completed drawing with tonal areas outlined and the
Eiger Scale value drawn within them or indicated with arrows. In
addition, you should have added background documentation: name of
formation, UT date, UT beginning and finishing times, seeing and
transparency, telescope, magnification, and your name and address.
You should also add the current solar colongitude and latitude.
Finally, it is helpful to have some notes regarding the observation
itself, with the approximate scale.
By now the
observation itself is nearly complete. If you still have sufficient
energy, you can start the finished drawing when you return indoors.
The initial stages of finishing the drawing are shown in Figure 4 (above).
However, you need not finish the drawing immediately if the observation was completed carefully in the first place. The finishing of the drawing depends on which drawing technique you wish to use. Figure 5 (below) is an example of a finished drawing made from the observation described above, using the stippling technique.
Figure 5. Lunar tonal drawing finished by using the stippling method.
Finished
drawing methods
Line Diagrams.
There are two basic approaches to making finished drawings from lunar
observations; line diagrams (outlines) or tonal drawings. There are
three methods of making tonal drawings, described later. It is simple
to finish an observation in terms of a line drawing. One needs to add
background information to make the observation useful to others, and
perhaps to tidy up the drawing, taking care not to alter any actual
details in the process. This type of finished observation is suitable
for scientifically-oriented programs. However, it is natural for
observers to want their finished drawings to appear as lifelike as
possible, and thus to seek other, more 'artistic' methods of representation.
Tonal Drawings:
Pencil Shading.
Most observers will use pencils to make their first lunar shaded
drawings. This is because pencils can be easily controlled and thus
used effectively by beginners. With sufficient practice, pencils can
be used to make beautiful and realistic drawings.
My best advice as
to which grade of pencil to use is to experiment and see what suits
you. Remember that too soft a grade will smudge easily, while too
hard a grade can damage the paper surface and also be harder to
remove entirely if mistakes are made. You can buy sets of pencils
which provide a good selection of grades from art shops, which may be
able to provide you with good advice.
The grade of paper
will have to be robust enough to be used outdoors without too much
wrinkling due to moisture. Paper is graded by its weight, and I
prefer 130 gsm [grammes per square metre; this reflects the system
used in Britain. Besides weight, paper is available in different
textures. One line of thought is to use the paper texture
deliberately to produce a desired effect. This approach is advanced
largely in order to improve reproduction. One drawback here is that,
as texture size increases, so too does the danger of the texture's
being interpreted as actual observed detail. Thus a compromise has to
be reached between smooth and rough texture; again the keyword is experimentation.
You can achieve
good pencil-shading effects through numerous layers of cross hatching
and slight softening by rubbing with a cotton ball. Alternatively,
you can lay down a less-precise layer of cross hatching and use
harder rubbing with a cotton ball. Then the lighter areas can be
picked out with an eraser, and the darker areas filled in. One
refinement is to use black ink for shadows, remembering that not all
lunar shadows are totally black. White paint can be used to bring out
exceptionally bright areas. This last method has the disadvantage
that, if you subsequently use a cotton ball to smooth shading, the
recesses in the paint will be shaded as well.
The best advice
for photocopying pencil drawings is to make your drawing with shading
as dark as you can accept, and then to turn up the copying machine's
contrast by a notch or two. These copies will probably suffice for
sending observations to program Recorders and other colleagues. If
later on the drawing needs to be published, you should send the
original by registered mail.
Tonal Drawings: Stippling.
This method, along with hatching, is best exemplified by the work of
Harold Hill [8]. It is likely that these methods originated in
response to the problems of reproducing continuous-tone drawings. We
are all familiar with stippling as used for reproducing pictures in
newspapers and magazines. This process builds up a picture using many
small black dots, which blur together into a grey sensation when
viewed from a distance. Manual stippling works on a similar
principle; and since the picture is made up of discrete black ink
dots, simple photocopying machines have no trouble in copying them,
with the copy virtually as good as the original.
In making a
stippled drawing, skill is needed in order to make the dots
unobtrusive for anyone viewing the drawing. The factors that are
involved in this method are dot density, size, spacing, and the time
spent in producing the drawing. The greater the dot density, the
greater the apparent darkness of any area, so this density should be
matched with the intensity noted in the original observation. The
second consideration is that the smaller the dots, the less
distracting they will be.
The size of the
dots is governed by the size of the pen point; I usually use 0.25 mm,
0.3 mm, and 0.35 mm; more rarely I use 0.5 mm. My favorite size is
0.3 mm because 0.35 mm is, I think, a bit too "coarse,"
while stippling can take too much time with 0.25 mm dots. You can use
larger pen sizes if you reduce your drawing in copying; reducing a
0.5mm dot drawing to about 70 percent of original size gives good
results. You can also enlarge drawings for displays.
The choice of type
of pen is vast, ranging from professional drafting pens to felt-tips.
You need to
compromise between durability and cost. Professional pens are more
expensive, but will last almost indefinitely if treated carefully;
this is just as well given the cost of replacement nibs! Felt-tips
are cheaper, but will blunt rapidly as you constantly tap them on the
paper surface.
The keywords here
are practice and patience. Also make sure to create the right
conditions for completing the drawing. Use good lighting to reduce
eyestrain. If possible, use a magnifying glass. Some form of support
for the magnifier is helpful, although I use a handheld 75-mm
diameter glass myself. Remember that stippling is time-consuming; in
my experience a drawing takes 1-1/2 to 2 hours or more to complete.
Thus do not be concerned if a stockpile of drawings builds up, each
awaiting its turn to be stippled. This is not a major problem if the
original observations were made carefully, with all the relevant
information included. Then, if you alter none of the original when
you make the final version, the finished drawing will not be far
removed from what you observed.
Tonal Drawings:
Ink Washes.
This last method consists of extremes. It is arguably the most
realistic method to portray the lunar surface if it is executed
beautifully; again, see the work of Harold Hill. It is also perhaps
the hardest method to master, and definitely the worst method for photocopying!
Constant practice
is the key to this method, and I am still not skilful enough to risk
using it on an actual observation. Thus, any or all of the previous
methods should be practised first, rather than risk ruining an observation.
To achieve the
various tones needed, you must apply various solutions of drawing
ink, diluted to different darkness levels. You then apply this ink
with soft hop hair brushes. Paper weight is important, and I would
not recommend using cartridge paper of weight less than 150 gsm with
this method.
References cited:
1. Jamieson, H.D.
& Phillips, J.H. 'Lunar Dome Catalog (April 30, 1992 Edition).'
J.A.L.P.O., 36, No. 3 (Sep., 1992), 123-129.
2. Benton, Julius
L., Jr. '1 Lunar Selected Areas Program (SAP): How to Get Started.'
J.A.L.P.O., 35, No. 3 (Sep., 1991), 100-103.
3. Jamieson, H. D.
'Getting Started: Telescope Selection.' J.A.LP.O., 35, No. 4 (Dec.,
1991), 181-183.
4. 'Our Readers
Speak: Telescope Selection-Part II' J.A.LP.O., 36, No. 2 (July, 1992),75-78.
5. Benton, op
cit., p.103.
6. Westfall, J.E.
'Getting Started: Moonlighting.' J.A.L.P.O., 36, No. I (Mar., 1992),23-25.
7. Pedler, J.
'Making Shaded Drawings That Will Photocopy.' The New Moon, 6, No. 2
(Dec.. 1992), 38.40.
8. Hill, Harold.
'A Portfolio of Lunar Drawings'. Cambridge: Cambridge University
Press, 1991.
9. Price, Fred W.
'The Moon Observer's Handbook'. Cambridge: Cambridge University
Press, 1988.
10. Rükl,
Antonín. 'Atlas of the Moon'. London: Hamlyn Publishing, 1991.