Asteroid 288, discovered in 1890 by the German astronomer (Karl Theodor) Robert Luther (1822–1900). Glauke is an S-type asteroid of diameter 32 km. It is the slowest-spinning asteroid known, with a tumbling rotation period of 50 days. Its orbit has a semimajor axis of 2.76 au, period 4.59 years, perihelion 2.20 au, aphelion 3.33 au, and inclination 4°.3.