The surface of a sphere, like the sun, can only oscillate in certain ways. The mode of oscillation is defined by the number of latitudinal and longitudinal nodal planes. This applet gives a redshift/blueshift snapshot view of the sun as it vibrates in one of these modes. (The real sun vibrates in multiple modes simultaneously, each mode typically having a different amplitude.) Observing the amplitudes of the various solar oscillation modes is a way to look inside the sun. (Density variations can be inferred from the relative amplitudes of the various oscillation modes, for example.)

You can use the scroll bars to change the nodal plane numbers. When you do, it will take the applet a few seconds to re-calculate the image. I also have a dynamic version of this applet accessible via a fill out form.

This is a translation of John Kennewell's BASIC program appearing in the "Astronomical Computing" section of Sky & Telescope, June 1997, pages 91-94. See that article for more information, and see Sky & Telescope's list for all their astronomical BASIC programs.

This program inspired me to re-read the chapter in my "Boundary Value Problems" book which winds up with Legendre polynomials. That's how one figures out where the nodal planes must be.

For another astronomy-related JAVA applet, see the exploding satellites in my relativistic orbit simulation.

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