did not carefully distinguish which of the two was the brighter when he assigned his eponymous designations in 1603. Although the characters of myth are twins, the actual stars are physically very different from each other.

? Gem (Castor) is a sextuple star system 52 light-years from Earth, which appears as a magnitude 1.6 blue-white star to the unaided eye. Two spectroscopic binaries are visible at magnitudes 1.9 and 3.0