Page:Popular Science Monthly Volume 58.djvu/659

Rh Aside from the determination of the solar parallax, Professor Pickering has pointed out that Eros furnishes an opportunity for the investigation of several interesting photometric problems. These are: the determination of the planet's diameter; a test of the law that the light varies inversely as the square of the distance; a test of the existence of an absorbing medium within the solar system, and a test of the law connecting the phase angle of a planet with the variation in brightness.

Thus Eros, the tiny asteroid, whose total area is little larger than the State of Rhode Island, is for the moment of more importance in the eyes of the astronomical world than the greatest planet which moves about the sun.