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PLANETS AND THEIR SATELLITES

millions of miles, and a combined effort was made at various observatories to lay down its exact position from night to night among the stars by photography, with a view to determining its parallax. But the planet was faint, the observations were difficult, and it is not yet known what measure of success was reached.

Variations of light which might be due to a rotation on their axes have been suspected in the case of other asteroids besides Eros, but nothing has yet been settled.

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