Planetary Doodles

SCINTILLATION SQUIGGLES: Everyone knows that stars twinkle but planets do not. The reason has to do with angular size. Stars are distant pinpricks smaller than the thermal irregularities in Earth’s atmosphere that refract their light. Each packet of air that passes in front of a star produces a well-defined change in color or brightness. Planets, on the other hand, are relatively nearby and wide; they span many atmospheric irregularities, which tends to smooth out the prismatic action.

Photographer Monika Landy-Gyebnar of Veszprem, Hungary, has found a kinetic way to demonstrate the effect. “When photographing a star or planet, kick the tripod during the exposure.” She’s applied this technique to many stars and planets, and the resulting collection of squiggles reveals the character of their twinkles:

“If we take a photo of a star with a shaking camera, the result is a wavy line with many colors,” she points out. “If we photograph a planet, however, there is no change; the color and width of the squiggle are nearly constant.”

The scintillation effect is greatest for stars near the horizon, which must shine through a greater distance of turbulent atmosphere. Angles noted in the image above are altitudes. The lowest-hanging stars display the strongest and most colorful twinkling.

“Demonstrating this is a ‘must-do’ thing when you give a lecture or show on astronomical observations for novices,” she concludes. Observing tips and more of Landy-Gyebnar’s “scintillation squiggles” may be found here.