The Sperling Files: Creating New Astronomical Computer Graphics and Animations

Norman Sperling

(c) 2002 Norman Sperling. Excerpted with permission from "What Your Astronomy Textbook Won't Tell You" (ISBN 0-913399-04-3).

Can you make computer graphics and animations? Here are various novel astronomical demonstrations. Select a project from this wish-list. Research the astronomy. Create the animation or graphics. Well-done versions may be used in future classes.

Telescope Focal Ratios

Read my article “Of Pupils and Brightness,” Griffith Observer, vol. 49, no. 1, January 1985, pp. 14-19; also posted at www.everythingintheuniv.com/telescopes. Develop a standard screen format portraying the cross-section and ray-trace path for types of telescopes of standard 20 cm diameter. For each focal ratio, changing in whole numbers from f/3 to f/20, show what each of the following would look like: achromatic doublet refractor; and reflectors of Newtonian, Cassegrain, Coudé, Ritchey-Chrétien, Gregorian, Dall-Kirkham, Schmidt, Schmidt-Cassegrain, Maksutov, and prime-focus types. Include labeled scale bars in both metric and English units. Include circles showing the size, brightness, and contrast that the human eye would perceive through a 25 mm eyepiece (with 60° field of view) for each of these popular objects: the Moon, Jupiter, the Pleiades cluster (M 45), Orion Nebula (M 42), and the Whirlpool Galaxy (M 51). Users can see that varying the focal ratio dramatically changes image brightness, contrast, and size. A further elaboration would permit eyepiece focal lengths from 4 mm through 50 mm.

Objects Across the Spectrum

Crossfade imagery of prominent objects in order of wavelength, from every imaging satellite and radio observatory. Each object constitutes a separate project. Certain obvious objects: the Moon, the Sun, Jupiter, the Orion Nebula (M 42), the Crab Nebula (M 1), the center of the Milky Way, the Andromeda Galaxy (M 31), Centaurus A (NGC 5128).

Constellations in Three Dimensions

Using new distance data from the Hipparcos satellite, find the precise distance to each visible star in a constellation. Animate walk-arounds and walk-throughs which demonstrate their depth. Change brightness with distance. Obvious prominent constellations: Ursa Major, Orion, Coma Berenices, Scorpius, and Cygnus.

Types of Variable Stars

Develop a standard screen layout featuring a moving graph-line for the star's brightness (and, for pulsating variables, graphs for diameter and surface temperature), labeled with time intervals. Inset a cartoon of the star undergoing its changes. Include the star's name, its type, the speed-up factor (or elapsed time), a thumbnail description of the processes occurring, and the quantity of known members of that type. Where possible, obtain real light-curves from the American Association of Variable Star Observers, 25 Birch Street, Cambridge, MA 02138. Each type is a separate project: R Canum Venaticorum (rapidly rotating close binary stars); Algol (eclipsing binary stars); BY Draconis (rotating spotted stars); T Tauri (unsettled baby stars); Cepheid (regular throbbing red giant stars); RR Lyræ (related to Cepheids, but faster, with overtones); Mira (semi-regular long-period red giant stars); R Coronæ Borealis (dying giant stars coughing out soot); U Geminorum (recurring dwarf novæ). I suggest starting with 10 seconds per cycle but program it so that experience can suggest an optimum speed, and adjusting requires a minor plug-in, not major reprogramming.