- ACAMAR (Theta Eridani). Eridanus, the River, the embodiment of the Greek’s “River Ocean,” unlike real rivers has two ends. It now terminates in the brilliant first magnitude star Achernar (Alpha Eridani), the name from an Arabic phrase that means “the end of the river.” But Achernar is too far south to be visible from Greece. The original end of the river was the star we still call Acamar, which derives from the same phrase and means the same thing.