SKETCHING TOOLS AND TECHNIQUES
Sketching Jupiter is a rewarding and useful way to train your eye to see more, and capturing the details on paper will . give you an outstanding familiarity with the planet's features. You have to work quickly, however, spending no more than 10 minutes on each sketch because Jupiter's rotation is fast enough to alter the view on time-scales longer than this.
Two approaches to sketching have been popular with Jupiter observers, one showing the whole Jovian disk, the other being the "strip sketch."
The full-disk drawing uses a prepared blank outline, usually on a scale of 2 inches (50 mm) to the planet's diameter. This is about 1 mm per arcsecond, and some observers standardize on that, varying the diameter of the blank as Jupiter's apparent size changes. (The planet's size ranges from 33 arcseconds near conjunction to 50 arc-seconds at perihelic oppositions such as those of 1998 and 1999.) Whether you vary the blank's size or not, be sure that it properly shows the oval disk. A 70 degree ellipse template from an art-supply store fits the shape perfectly.
The strip sketch focuses on a range of latitude, such as the zone containing the Great Red Spot and its two flanking belts. Because they do not attempt to capture all of Jupiter at once, strip sketches are often easier and considerably less nerve-wracking for beginners. By focusing on an area of interest, you can spend your 10 minutes per sketch more carefully.
Besides the Jupiter drawing, the page should include space to note the date and time, the instrument and magnification used, the weather and seeing conditions, and any other factors-that seem relevant.