Astronomy/Capella

Advertisement

Expert: - 7/14/2004


Question
When I view Capella with an unaided eye or binoculars it seems to glitter and cast different colors like a prism. I wonder if you can tell me what causes this effect.

Thank you,

Mike

Answer
Hello.

The effect is related to *scintillation* - the same which produces the "twinkling" of stars.

Basically, the atmosphere disturbs the path of incoming star light and causes different degrees of refraction (the bending of light on entering a denser medium - in this case on entering the Earth's atmosphere from the vacuum of space).

Since different degrees of such refraction can also create or yield different colors, this is related to the same effect.

One can observe a marked difference in this effect when one observes a star like Capella from a high altitude - such as at the top of Pike's Peak  (alt. 14,200') in Colorado. There, hardly any twinkling or color variations can be seen.

On the other hand, the lower the altitude, the denser the layers of impeding atmosphere above, and the more the effect is likely to be amplified.

Astronomy

All Answers

Answers by Expert:

Ask Experts

Volunteer

Philip Stahl

Expertise

I have forty years of experience in Astronomy, specifically solar and space physics. My specialties include the physics of solar flares, sunspots, including their effects on Earth and statistics as applied to astronomical investigations.

Experience

Astronomy: more than forty years experience starting with construction of my own simple telescopes. Worked at university observatory in college, doing astrographic measurements. M.Phil. degree in Physics/Solar Physics and more than ten years as researcher.

Organizations
American Astronomical Society (Solar Physics and Dynamical Astronomy divisions), American Mathematical Society, American Geophysical Union

Publications
Solar Physics (journal), The Journal of the Royal Astronomical Society of Canada, The Proceedings of the Meudon Solar Flare Workshop (1986), The Proceedings of the Caribbean Physics Conference (1985). Books: 'Selected Analyses in Solar Flare Plasma Dynamics', 'Physics Notes for Advanced Level'.

Education/Credentials
B.A. Astronomy, M. Phil. Physics

Awards and Honors
American Astronomical Society Studentship Award (1984), Barbados Government Award for Solar Research

©2012 About.com, a part of The New York Times Company. All rights reserved.