a bright comet discovered by an American student, D. Morehouse, in September 1908 (designated 1908 III). It moved about the sun in a nearly parabolic orbit.
Observations of Morehouse’s comet provided a great deal of material for developing a physical theory of comets. Spectral observations made it possible to establish for the first time the plasma nature of type I tails of comets according to Bredikhin’s classification. The extremely low content of neutral gases and dust allowed the formation of contracting envelopes of comet heads to be traced; the passage of the head into the radial system of the tail could also be traced. The convergence of the rays to the axis of the tail like the spokes of a closed umbrella was first traced. Waves directed along the rays were discovered, as was the motion of material of the tail having accelerations greatly exceeding the gravitational acceleration of the sun.