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An Introduction to Planetary Drawing
I hadn't expected to see the feature on Jupiter that night. I had recently purchased a used Edmund 4-1/4"
f/10 equatorial reflector (for $60, which was a lot for me at the time) and that night was going to be first light.
During the day I cleaned the telescope, collimated the mirror and aligned the finder, and as it started to get
dark I set the scope outside to let it cool down. As Jupiter rose higher in the eastern sky I swung the telescope
over to it. I was surprised how much brighter and larger it appeared then in my smaller 60mm refractors that I
had used for a year up until then. As I scanned the planet with the low power eyepiece in I saw what appeared to
be a large red colored object. I inserted the high power eyepiece and focused and realized that I was seeing the
Great Red Spot for the first time.
I took out my flashlight, sketchpad, color pencils, and began to make a drawing of the planet, noting the date and time, sky conditions, telescope used, and magnification. At the time I assumed that the Great Red Spot would always be the deep red color it appeared that night. Little did I know at the time that in the coming years the Great Red Spot would began to shrink and fade in color, and I would look back at this drawing and other drawings I made at the time to see how it use to look when it actually resembled it's namesake. It was mid-September 1974, and this is the drawing that I made at the eyepiece that night.
Jupiter, September 15, 1974, 2:50 UT, clear sky with fair seeing. Callisto, Europa, and Io are to the left of the planet, while Ganymede is to the right. Edmund 4/1-4" f/10 reflector, 135x
Making a drawing while you are at the eyepiece observing the planets is one of the best ways to increase the
detail that you see. Not just on the planets or moon, but in deep-sky objects as well. This is because you are
training your eye to see more detail.
When I first started observing the planets I did not know anything about training my eye to see more detail. I simply made drawings because I wanted to make a permanent record of what I saw. The first one I made was of Jupiter using a 60mm achromatic refractor. Before setting up the telescope I took a sketchpad and drew a round circle on it to represent the globe. Next, while at the eyepiece I noted the date and time of the
observation, telescope and magnification used, and sky conditions.
The first time I observed Jupiter I expected it to look a lot like the photographs I had seen it in magazines and books taken with large professional telescopes. But what I saw wasn't much, just three brown-colored bands on a yellow ball. All three belts appeared to be the same width, one near the center of the globe, and the other two not far from the North and South Polar Regions. Even though what I saw was nothing like the pictures in the books I thought it was neat to be able to see detail on a planet almost 500 million miles away, so decided to observe again. Plus it was fun to see the four Galilean moons as they changed position night to night.
After a few weeks of observing and making drawings of Jupiter I gradually began to see more detail. The three belts no longer appeared to be the same width. The ones near the South and North Polar Regions appeared thinner then the one near the center. Also, the center belt now appeared to have white colored area in the middle, and on one night I even saw a shadow transit from one of the moons cross the face of Jupiter.
Since I was using the same telescope as a few weeks ago, the same magnification, the seeing conditions were about the same, and yet was seeing more detail, I realized that something else had changed. My eye was getting trained to see finer detail. Instead of just noting where the belts were I began to look for other more subtle features.
It may seem like a lot of work to make a drawing at the eyepiece. You may be sitting there thinking it is just extra stuff you have to carry outside with you, and besides you don't feel you are much of an artist. The thing is you don't need to be an artist to make a drawing at the eyepiece. All you need to do is to record on paper what you see.
Lets start simply. The next time you go out to observe a planet, such as Jupiter, get a sketchpad or notebook and draw a circle on one of its pages, say two and a half inches in diameter. Note that Jupiter's disk is not a circle but an ellipse, as the planet bulges slightly at the equator due to its rapid rotation rate: it completes a rotation in less then 10 hours. There are pre-drawn observing forms for the planets available from both The
Association of Lunar and Planetary Observers (ALPO) and The British Astronomical Society (BAA). Both are listed on my Links page. Also a simplified Jupiter observing form was printed in the October 2000 issue of Sky and Telescope magazine on page 128.
Bring your form outside with you when you go out to observe. Here is a list of some basic supplies to help you get started:
- Get a clipboard to hold your observing form. This makes it easier to make the drawing while at the eyepiece.
- Attach a book light to the clipboard, or have some other small flashlight that you can hold in your hand along with the clipboard, so that you don't have to hold a flashlight in your mouth while you are trying to draw.
- Decide whether you want to make your drawings using either a lead pencil or color pencils. Have a soft eraser handy as well. If you want to use a lead pencil, you can start out with a #2 lead pencil. When you are making your sketch you will want to be able to show that one feature is darker or lighter then another, and you can either do that using the #2 lead pencil, or buy pencils that have different shades. Art supply stores carry these pencils, such as those made by Sanford. Several to consider getting would include a 4B (darkest), 3B (medium), H (lighter), and 4H (lightest).
- If you want to use color pencils, art supply stores carry different brands. You can buy a box of colored pencils from Prismacolor, Crayola, or from other manufacturers. Once you have made a few drawings you may find that you want other colors, and most art supply stores carry individual pencils for sale, from companies like Berol, Derwent, Rexel, and Sanford.
- Note that if you are making a color drawing try using a flashlight with a white light rather then a red one as it us difficult to distinguish colors when using a red light.
It is a good idea to keep your clipboard, forms, flash light or book light, and pencils together in one place so you can grab them on a moments notice. There are times when you don't feel like making a drawing because you have along day at work and are tired, or just want to get a quick observing session in. Murphy's Law being what it is though it is nights like these when you don't have your drawing materials handy that the seeing can suddenly get very good or excellent, and you end up back inside searching for 20 minutes your pencils or forms. When you finally get back outside the seeing has gone from excellent to poor.
Saturn, January 3, 1976 3:30 UT, clear sky with fair seeing. Cassini Division prominent. Equatorial Zone appeared white in color. Equatorial Belt light brown in color. Rhea is to the upper right of Saturn, while Titan is to the right. Criterion RV-6 6" f/8 reflector, 140x.
Once your telescope is cooled down pull your chair up to the eyepiece. Note that you will find it much easier
to sit and make a drawing then try and stand. Record on your paper the date, the time you begin your observation,
the telescope and magnification used, sky conditions (is it clear, hazy, partly cloudy; does the image of the planet
seem steady). When you are recording sky conditions remember that you are considering two factors. One is transparency,
and the other is seeing.
Transparency and Seeing
Transparency is equal to the faintest star visible to the unaided eye. Many observers use the stars in Ursa Minor, The Little Dipper, to determine the transparency.
Seeing is an estimate of how steady the atmosphere is. There are two scales, both related. One was developed by Eugene Antoniadi, a well-known planetary observer. The second one was developed by ALPO.
On Antoniadi's scale a seeing of I corresponds to perfect seeing with steady images even at high magnification; II is intervals of perfect seeing with occasional periods of less stable seeing; III denotes fair seeing with frequent unsteady images so that medium magnifications are used; IV is poor seeing that offers only occasional glimpses of detail; while V is very poor with blurred images even at low power.
On the ALPO scale a seeing of 9-10 corresponds to Antoniadi's seeing of I or perfect seeing; 7-8 on the ALPO scale would be very good seeing corresponding to Antoniadi's II; 5-6 on ALPO scale would be good seeing corresponding to III on Antoniadi's scale; 3-4 on ALPO's scale would be fair seeing corresponding to IV on Antoniadi's scale; while 1-2 on ALPO scale would be poor seeing corresponding to V on Antoniadi's scale. You can use whichever scale you wish as long as you keep track of which one it is.
An easy way to remember is to think of seeing in terms of the highest magnification you can use when observing the planets. If you can employ a magnification of 50x or 60x per inch of aperture or greater and the image is still steady then your seeing would correspond to I on Antoniadi's scale and 9-10 on ALPO's scale. If you can employ similar magnification or a little lower but there are occasional periods of less stable seeing then your seeing would correspond to II on Antoniadi's scale and 7-8 on ALPO's scale. If you are able to only employ medium magnifications, say between 20x to 30x per inch of aperture, your seeing would correspond to III on Antoniadi's scale and 5-6 on ALPO's scale. If you are observing and using
between 20x to 30x per inch of aperture or less but only occasional glimpses of detail then your seeing would correspond to IV on Antoniadi's scale and 3-4 on ALPO's scale. If your are using low power and only seeing blurred images then you're seeing would correspond to V on Antoniadi's scale and 1-2 on ALPO's scale.
Some general considerations about local seeing effects. Natural vegetation, such as a grassy field, make a good observing location. Manmade objects, such as asphalt parking lots, streets, and buildings, absorb solar radiation during the day, and release it slowly at night. This can adversely affect seeing.
When possible, try to observe when the planet is 45 degrees or higher above the horizon as you will be looking through less atmosphere and the seeing tends to be better. Also, the seeing is often steady right after sunset, as well as after midnight as much of the heat that has been absorbed by the surface of the earth has been released by then. This can be particularly true around sunrise.
As a general rule, when the jet stream is located over your observing area, the seeing is not very good. The same holds true for high altitude air turbulence. There are a couple of websites that can give you idea of the position of the jet stream, as well as turbulence.
The seeing is often poor as well after a cold front has passed through your observing area. However, the seeing
usually improves when the center of the high-pressure system is over your area, and as it begins to move away.
Some of the best seeing can occur on warm and humid nights when the transparency is poor, and ground fog is forecast,
as it indicates that the atmosphere is very steady.
Making a Drawing
Now look at the planet and draw on the paper what you see. At this point you may be thinking that yes you see a few features but it doesn't seem worth making a drawing. Make one anyway, and when you are recording the features ask yourself a few questions:
- Do all of these features appear to be the same size?
- Do all of these features appear to have the same height and width?
- Do all of these features appear to have the same tone, or are some darker or lighter then others?
- Do all of these features appear to have a smooth outline, or are there irregularities visible?
- Are there any differences in color?
Here are some sample drawings of Jupiter, and a few easy steps that can be used to complete your drawing:
Step 1 - Note the date and time on your form, seeing and transparency, as well as the telescope, magnification and any filters used;
Step 2 - Sketch the outlines of all of the detail you can see. Note in this example I am using color pencils but you can use a standard lead pencil:
Step 3 - To help position the planetary features you see on your sketch correctly you can try thinking of where
these features begin and end in
terms of a clock face. As an example, a particular belt on Jupiter may start at the 2 o'clock position and extend across to the 10 o'clock position.
You can use the same method to determine how wide a belt appears;
Step 4 - Now shade in the detail. If a feature, such as a belt on Jupiter, appears darker then another one, try to show that in your drawing:
Step 5 - Record the time you finished your drawing. Note that the planets are rotating as you are making your
drawing, so to preserve accuracy you
should try to complete your drawings in 20 minutes or less.
Once you are finished making your drawing and are back inside you may pull out a magazine with some nice images of Jupiter and think to yourself that your drawing doesn't look anything like that. But don't feel bad because my first drawings didn't either. My first drawing of Jupiter looked more like a yellow tennis ball with a few brown lines on it.
The next time you go out to observe make another drawing. Over time as you make more drawings you will find that indeed you can see more detail. These drawing will serve as a permanent record of how the planet appeared to you during a particular year.
I found that as I made drawings of the planets and began to see more detail that I felt I got to know the planetary features better. I would consult a book and learn what the belts and features on Jupiter were called, and what Saturn's rings were composed of.
Also I began to look forward to observing the planets each new season. For, not only was I beginning to see more detail as I trained my eye more, but I learned also that features on the planets would be change from year to year as well. Night after night I would look forward to see if new feature would become prominent on the surface of Mars, or some change would take place in Jupiter belts, or some transitory detail in Saturn's rings would present itself.
Mars, July 25, 1986, 4:45 UT. Melt band visible along edge of South Polar Cap, as well as small rift. Solis Lacus prominent, as is Titonius Lacus. Limb cloud noted in North Polar Region. Astro-Physics 6" f/9 refractor. Magnification 198x with orange filter. Seeing 5-6 on ALPO scale.
Of course, if you mention that you have an interest in the planets to some people they may get the wrong idea.
When I was in high school I went over to visit a friend one day and when I walked into the kitchen a friend of
his mom's turned to me and said, "So I hear your into astrology. Tell me about myself!" I was caught
a little of guard as I never had anyone confuse astronomy with astrology before, so simply replied, "No, I'm
interested in astronomy, such as telescopes and observing." "Oh", she replied, "Well, your
into the wrong thing then." If the same thing happened today I would have a few choice words in reply, but
at the time just tried to be diplomatic.
Keeping a Log Book
My other suggestion would be that in addition to making drawings at the eyepiece is to keep a log of your observations. Record information like the weather conditions, such as seeing and transparency, date and time of observation, telescope and eyepieces used, and anything else that you wish to record. It can be something as simple as writing down your observations in a log book, or taking notes at the eyepiece and transferring them to a computer when you get back inside. Your notes may include how well a particular eyepiece of filter worked with the telescope, how a new accessory performed, and success or failure in finding deep-sky objects or seeing some elusive planetary feature.
Keeping a log book may seem like extra work, but over time these notes will become invaluable to you, as you will begin to correlate how the combination of telescope aperture, magnification, filters, and weather conditions are best for observing the planets and moon or deep-sky objects. This is particularly true when you attend star parties and get a chance to try telescopes or eyepieces that you don't own yourself. I enjoy reading through observing logs that I made years ago to see the kind of detail I saw in objects with telescopes I owned back then, versus the kind of detail I see today with my current telescope equipment.
Making a drawing at the eyepiece one of the best ways to learn to see more detail. This holds true not just
for the planets or moon, but for deep-sky objects as well. This is because you are training your eye to see more
detail. The best way to begin is to start out making simple sketches, and then as your interest grows make more
detailed drawings. At the same time you will be making a permanent record of how the object appeared during that
particular observing session. Keeping a logbook is another good idea, as it gives you a permanent written record
of your observing sessions.
After a while you may find that you enjoy making drawings and you may decide to concentrate on making sketches of a particular subject, such as the planets, the moon, or deep-sky objects. One such example is a superb book by Stephen James O'Meara entitled The Messier Objects. In the book he made detailed drawings of all of all 109 Messier objects using a 4" refractor. The detail in these drawings is remarkable. In part this is because of his renowned observing skills, and also because he made these observations from a very dark sky location.
However, it shows also what a patient and persistent observer can do with a telescope of relatively modest aperture and who is willing to spend time studying an object and making a sketch of it to see the faintest detail visible. There are times when we observe an object with our telescopes and think, "Yes, it looks nice in this aperture telescope, but I wish I had a larger aperture telescope so I could see more." By making drawings, we can learn to see more with the telescope equipment that we own, and come to appreciate the wonders of the universe even more.
Eric Jamison is an experienced astronomer and enjoys doing sketches at the eyepiece. He has an excellent webpage full of articles, drawing and personal reviews at http://home.fiam.net/ericj/