THE ASTEROIDS, A FAMILY OF DWARF WORLDS Beyond Mars, in the broad gap separating the terrestrial from the Jovian planets, are the asteroids, of which nearly five hundred have been discovered and designated by individual names or numbers.

But any statement concerning the known number of asteroids can remain valid for but a short time, because new ones are continually found, especially by the aid of photography.

Very few of the asteroids are of measurable size.

Among these are the four that were the first to be discovered--Ceres, Pallas, Juno, and Vesta.

Their diameters, according to the measurements of Prof.E.E.Barnard, of the Yerkes Observatory, are as follows: Ceres, 477 miles; Pallas, 304 miles; Juno, 120 miles; Vesta, 239 miles.
It is only necessary to mention these diameters in order to indicate how wide is the difference between the asteroids and such planets as the earth, Venus, or Mars.