Ismene is asteroid #190 and of the type X or P. Ismene belongs to the group Hilda, which means that Ismene is in a 3:2 orbital resonance with Jupiter. Ismene’s orbit is characterized by a semi-major axis of 3.98 Astronomical Units, an eccentricity of 0.17, a period of revolution of 2 902 days, and an inclination of 6.2 degrees. Ismene was discovered by the German-American university teacher and astronomer Christian Heinrich Friedrich Peters at the Litchfield Observatory of the Hamilton College, Clinton, New York, USA.

Ismene is named after Ismēnē (Ἰσμήνη), a princess from Greek mythology. She is the sister of Antigónē (Ἀντιγόνη), after whom the asteroid Antigone is named. Ismēnē (Ἰσμήνη) admires the braveness of Antigónē (Ἀντιγόνη), but lacks in own braveness. So she argues that women should not get involved in politics and she simply obeys the king’s orders. Ismēnē (Ἰσμήνη) nevertheless gets murdered for political reasons by Tydeús (Τυδεύς), who is one of the seven heroes lead by Polyneíkes (Πολυνείκης) to reconquer the throne of Thebes, while Ismēnē (Ἰσμήνη) met her lover Periklýmenos (Περικλύμενος), who is one of the warriors fighting for Eteokles (Ἐτεοκλῆς). This must have happened after the epic battle for the throne because otherwise Ismēnē (Ἰσμήνη) couldn’t have met her sister Antigónē (Ἀντιγόνη) and couldn’t have discussed questions of morals with her. But there are several follow-up tales, where the battles between the warriors of both sides didn’t end after Polyneíkes (Πολυνείκης) and Eteokles (Ἐτεοκλῆς) both fell in the epic battle.

Ismēnē (Ἰσμήνη) commonly is seen as the perfect conformer. So the asteroid Ismene should indicate perfect adaptation to social standards. Although only out of fear.