It was discovered by German astronomer Robert Luther on 23 November 1867, and named after one of the various Arethusas in Greek mythology.

Arethusa has been observed occulting a star three times:[7] first on 2 February 1998, and twice in January 2003.

[citation needed] This object is orbiting the Sun with a period of 5.36 years and an eccentricity of 0.15.

The cross-section diameter is around 136 km and it is spinning with a rotation period of 8.7 hours.

The spectrum matches a C-type asteroid, indicating a dark surface with a primitive carbonaceous composition.