2135 Aristaeus (1977 HA) is an Apollo asteroid discovered on April 17, 1977, by E. F. Helin and S. J. Bus at Palomar Observatory. It is named for Aristaeus, the son of Apollo and the nymph Cyrene. 2135 Aristaeus is a potentially hazardous asteroid (PHA) because its minimum orbit intersection distance (MOID) is less than 0.05 AU and its diameter is greater than 150 meters. The Earth-MOID is 0.0100 AU. Its orbit is well-determined for the next several hundred years. The asteroid made its closest approach to Earth on April 1, 1977, at a nominal distance of 0.03216 AU. It will make its next closest approach on April 2, 2064, at a nominal distance of 0.0546 AU.