Hampshire Astronomical Group - Clanfield Observatory

Four hundred years ago, when Galileo made his first telescopic observations of the Moon, he naturally had to make drawings to record what he’d seen. For another three centuries, drawing remained the only way of recording what was seen at the eyepiece, until the advent of astronomical photography in the latter part of the 19th century. Incidentally, the accolade for making the first telescopic drawings of the Moon should go to a little-known English astronomer, mathematician and explorer called Thomas Harriot, who actually beat Galileo to it by a matter of months; but that’s another story.

The immediate question is, “Why draw?” During recent years, computer technology and in particular digital imaging have revolutionised astronomy. We’ve become accustomed to impressive digital images of astronomical subjects which reveal detail and colour not apparent to the eye. At first, it would seem that there’s no longer any need to go to the effort of producing drawings.

After all, why bother to stand at your ‘scope with pencil and paper when you can use a camera? Firstly, the essence of astronomy is to observe and there is really nothing like drawing for developing your observational skills. Secondly, producing a drawing greatly enhances your knowledge of what the subject really looks like. Artistic ability is by no means a prerequisite, the aim is technical accuracy; you don’t need to make any sort of artistic statement!

Shown here is a sequence of three images showing the main stages of making a Moon drawing, in this example of the crater Cassini. The first stage is to study the subject carefully, making note of the proportions and relationships of objects within the drawing. Note the faint ruled lines representing the ellipse upon which the main crater outline is constructed. Construction is the most important stage of the drawing and is the foundation on which the final result is built. Any errors are best detected and corrected at this stage.

Figure 1 – Cassini Outline Construction

The second stage of the drawing is to study light and shadow. The airless lunar environment produces stark contrasts, varying from deep black shadow to dazzling white features. In between these two extremes there is a range of grey tones which the observer needs to assess. As the Moon orbits the Earth and the Earth spins on its axis, this causes the light falling on the lunar surface to change rapidly, especially as seen through a telescope. Having necessarily spent a while constructing the drawing, the best method is to use a ‘paint by numbers’ technique to quickly note tone values on the drawing. The tones can then be shaded in at leisure after the observing session. In this example I’ve used my own tone range of 1 to 7, where 1 is black, 4 is mid-grey and 7 is white. Add a title and notes of the date and time, magnification, seeing conditions and any other relevant details.

Figure 2 – Tone Values

The third and final stage is best done after the observing session, when time and care can be taken to achieve accurate shading. There are various techniques and materials for shading, including cross-hatching, stipple effects and even the use of ink or paint. This is a matter of individual preference and it is worth a bit of experiment at the outset. When the drawing is finished, I’d recommend using a fixative spray to prevent the drawing getting smudged.

Do have a go at drawing the Moon, at the least it will develop your observational skills and you may well be pleasantly surprised at the results. Above all, enjoy your astronomy!

Drawing The Moon