It was discovered by German-French astronomer Hermann Goldschmidt on March 31, 1856,[6] and named after Harmonia, the Greek goddess of harmony.

The spectrum of 40 Harmonia matches an S-type (silicate) in the Tholen classification system, and is similar to primitive achondrite meteorites.

[7] Photometric observations at the Organ Mesa Observatory in Las Cruces, New Mexico during 2008–09 were used to generate a light curve that showed four unequal minima and maxima per cycle.

[4] Speckle interferometric observations carried out with the Nicholas U. Mayall Telescope at the Kitt Peak National Observatory during 1982–84 failed to discover a satellite companion.

[8] In 1988 a search for satellites or dust orbiting this asteroid was performed using the UH88 telescope at the Mauna Kea Observatories, but the effort came up empty.