ABSTRACT
The first great comet of the period we are now considering was the celebrated 1858 comet of Donati, the finest comet within living memory, though not considered quite as bright as that of 1811. The gegenschein also belongs to the ecliptic, and is a very faint luminous patch sometimes seen in the direction exactly opposite to the sun. It is generally taken to represent some effect of the earth's cone of shadow, or of the sunlight just beyond the shadow, but the details are uncertain. It has been considered probable, if not certain, of late years that the zodiacal light and the gegenschein are not distinct phenomena in as much as they have at times been seen at favourable stations such as Arequipa, connected by faint zodiacal bands, leading to the inference of an extension of the formation, whatever it may be, far beyond the earth's orbit.
