It is a variable star visible to the naked eye, around 380 light years from the Sun.

η Geminorum is 0.9 degree south of the ecliptic, so it can be occulted by the Moon[20] and, rarely, by planets.

[citation needed] In 1865, Julius Schmidt first reported that η Geminorum was a variable star.

The light variations were described by Schmidt and other observers as having long maxima of constant brightness, minima of greatly varying size and shape, and a period around 231 days.

[5] In 1902, William Wallace Campbell reported that η Geminorum A showed radial velocity variations.

Due to the appearance of the spectrum, the spectroscopic companion is suspected to be a fainter M-class star.

[5] Since the secondary star alone would be too small to cause the observed eclipses, it is probably surrounded by a circumstellar disk.

[29] USS Propus (AK-132) was a United States Navy Crater class cargo ship named after the star.