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The Shallow Sky

Always Kvetching about Sketching

Akkana Peck

A drawing made by Christiaan Huygens in 1655. Courtesy of PPARC at Please see other illustrations in the PDF version of the newsletter.


Why am I always talking about sketching? Isn’t that something that’s only fun for kids and art students?

Nope! Sketching is worthwhile (and fun) for any observer, and I’ll be talking about some of the benefits, tips on how to get started, and maybe even some hands-on practice, at the SJAA Beginning Astronomy class on September 15th. Show up and see what it’s all about!

But I’ll give you a few highlights now. You may be wondering: what’s the point? Here are some of the benefits to sketching what you see through a telescope eyepiece:

Sketching forces you to look in more detail, and ask yourself what you actually see. You’ll end up seeing a lot more than you would otherwise.

You’ll have a permanent record of what you saw, including lots of details you wouldn’t think to put in an observing log.

Sketches are really interesting to look back on later.

Sketches give you a way to compare what you see in different scopes, from different sites and seeing conditions, and over time as you get more practiced.

Sketches give you a way to show other people what you can see through your telescope.

Why not just snap a photo?

Surprisingly, even with today’s amazing digital camera technology, the human eye can still pick out details that a camera won’t show.

Of course, you’re not going to see those amazing color details in faint galaxies and nebulae which are so beautiful in photographs. A camera is the only way to collect that.

But consider: have you ever seen a photograph that captured the glittering pinpoints of the Trapezium while still showing the full extent of the Orion nebula, its knots and wisps extending outward from the four stars at the center? A camera can’t show both at once: you have to choose between a short exposure, which shows the stars but not the nebula, or a long exposure, which gives a beautiful and colorful nebula with a white, blown-out central portion in which the stars can no longer be distinguished.

Same for globular clusters: have you ever seen a photograph that showed the glittering three-dimensional snowball you see through the eyepiece of a big scope?

Or consider the moon or Jupiter. A photograph can’t capture the bright three-dimensional gleam of a Galilean moon hanging just over the limb of Jupiter, or the shining tip of a lunar mountaintop poking just barely up into the light beyond the terminator.

All these sights have a wide dynamic range: the difference between the brightest and dimmest parts is very large. Cameras (either digital or film) can’t record the dynamic range the eye can see. But you can record all those details in a single sketch. With practice, sometimes you can even make the sketch show something of the beautiful view you saw in the eyepiece.

In addition, the eye can react faster than a camera. When you’re observing bright shallow sky objects, you can catch those instants of good seeing that in a photo would get averaged with the bad moments on either side. Modern CCD astrophotographers compensate for this by taking hundreds, sometimes thousands, of photos of the same object, searching through them for the good ones, then either taking the best, or combining many images together using a technique known as “stacking”. This produces great images, but it’s a lot of work, and much of the time it doesn’t even show as much detail as you could have seen yourself though an eyepiece.

And besides – a pencil is a lot cheaper than a CCD camera rig, a laptop and the stacking software!

I know what you’re thinking. “I’m not an artist! Everything I draw looks terrible!”

Don’t think in terms of making art to frame and put on the wall. If you practice, you’ll probably eventually produce attractive and cool looking sketches; but there are lots of reasons to sketch even if you never get to that point.

If you doubt that, look at the history of science, like the sketches of the moon, Mars or Saturn from scientists like Galileo, Lowell, Huygens, Cassini. Most of these scientists weren’t artists, and their sketches often weren’t pretty; but they were cutting edge science at the time, and the early astronomers traded their sketches and compared the what they saw while they tried to understand it.

“Well, okay, I guess I could try it. But I don’t have any special drawing pencils or anything!”

You don’t need any special equipment. The back of an envelope and any pencil will work fine. A comfy chair helps: you’ll be able to concentrate a lot better on the object you’re looking at. Find some sort of flashlight you can clip somewhere, so you don’t have to hold it in your teeth: a head-mounted light, a little book light (sometimes you can find them at dollar stores), a flashlight with a clip, whatever you can find.

If you’re sketching deep sky objects, the number one trick is to draw a negative image. Don’t try to draw a black sky with white stars; let the paper represent the black sky, and draw white where the stars are and shades of grey for the nebula or galaxy. You can look at the finished drawing as being like a photographic negative, like they used to use for scientific research; or you can scan it into a computer and invert it digitally.

If you’re drawing planets, you don’t have to worry about inverting the image. Just try to draw what you see. Use a regular graphite pencil at first. Colored pencils are trickier and I don’t recommend them when you’re starting out.

When sketching the moon, the trick is to narrow your focus.It’s easy to get lost in putting in too much detail and end up not getting anything. Try showing just one crater, or just one interesting shadow, and a tiny bit of detail around it.

There are lots more tips that can help, but I’m out of space, so come to the class later this month and I’ll tell you all about it!

Until then, you can try looking at planets. But there’s not that much to look at this month:

Uranus is at opposition on September 5th, in Aquarius, so it and nearby Neptune (in Ophiuchus) are well placed for late night observing all month.

You can still catch Jupiter, very low in the early evening sky, before it disappears in the sunset glow. There are numerous double shadow transits this month (check the RASC Observer’s Handbook or a computer program that shows Jovian moon shadows) though they will become increasingly challenging as Jupiter falls lower in the sky.

Morning observers can catch Saturn, low in the dawn sky, drawing farther from the sun as the month progresses. Venus can be caught low in the dawn sky early in the month, but moves too close to the sun to see by mid-month. Mars and Mercury are hidden in the sun’s glare.


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