158 Koronis /kəˈroʊnᵻs/ is a main-belt asteroid that was discovered by Russian astronomer Viktor Knorre on January 4, 1876, from the Berlin observatory. It was the first of his four asteroid discoveries. The meaning of the asteroid name is uncertain, but it may come from Coronis the mother of Asclepius from Greek mythology. Alternatively, it may come from Coronis, a nymph of the Hyades sisterhood.
From its spectrum this is classified as an S-type asteroid, indicating a stony composition. Photometric observations show a synodic rotation period of 14.206 ± 0.002 hours with a brightness variation of 0.28–0.43 in magnitude. A subsequent study at the Altimira Observatory during 2010 was in agreement with this estimate, yielding a rotation period of 14.208 ± 0.040 hours. Based on a model constructed from the lightcurve, the shape of Koronis resembles that of Ida, although it is a bit larger. 
The asteroid itself may not be spectacular, but the Koronidian family of asteroids named after it is one of the most important. This cluster was created during a collision some 15 million years ago, with 158 Koronis retaining about 98% of the combined mass. One member of the family, 243 Ida, has been visited by spacecraft, and gives some idea of how the other asteroids in the family may look.