Astronomy Picture of the Day . ... Credit Copyright: Walter Lewin ( MIT ) Explanation: What caused this ring of colors? At the time of this writing, MIT Physics Professor Walter Lewin had yet to find someone who can give the correct explanation. ... Not APOD editors . ... Shortly after he gives the explanation on December 7 during a lecture in his course Vibrations and Waves at MIT, APOD will carry a link to it. ... NASA Web Site Statements, Warnings, and Disclaimers . ... The Solar Spectrum . ...