When in aphelion, or at its greatest distance, Eros is outside of the orbit of Mars, but when in perihelion it is so much inside of Mars's orbit that it comes surprisingly near the earth.
Indeed, there are times when Eros is nearer to the earth than any other celestial body ever gets except the moon--and, it might be added, except meteors and, by chance, a comet, or a comet's tail.

Its least possible distance from the earth is less than 14,000,000 miles, and it was nearly as close as that, without anybody knowing or suspecting the fact, in 1894, four years in advance of its discovery.

Yet the fact, strange as the statement may seem, had been recorded without being recognized.

After De Witt's discovery of Eros in 1898, at a time when it was by no means as near the earth as it had been some years before, Prof.E.C.Pickering ascertained that it had several times imprinted its image on the photographic plates of the Harvard Observatory, with which pictures of the sky are systematically taken, but had remained unnoticed, or had been taken for an ordinary star among the thousands of star images surrounding it.

From these telltale plates it was ascertained that in 1894 it had been in perihelion very near the earth, and had shone with the brilliance of a seventh-magnitude star.
It will, unfortunately, be a long time before Eros comes quite as near us as it did on that occasion, when we failed to see it, for its close approaches to the earth are not frequent.