Mebsuta (Epsilon (ε) Geminorum) is a mag. +3.0 star in Gemini, part of the northern twin Castor.
You’d be forgiven for assuming its name translates to something to do with the twins, but it actually means ‘outstretched paw’.
Equally as curious, 6.5° southeast of Mebsuta lies Mekbuda (Zeta (ζ) Geminorum), the name of which means ‘the lion’s folded paw’.
As you might now guess, the names relate to a lion, this being a pattern recognised in ancient Arabic stories.
Mebsuta facts
Mebsuta has a spectral classification of G8 Ib, which means it’s a yellow supergiant and its spectrum is used as a reference against which other stars are compared.
With a mass 5.3 times that of the Sun, Mebsuta’s radius has been measured directly by the Navy Precision Optical Interferometer at the Anderson Mesa Station of the Lowell Observatory in Arizona.
This allowed the star’s size to be determined as 130 times larger than the Sun.
As Mebsuta sits just under 2° from the ecliptic, it’s a candidate for lunar occultations. When this happens, high-resolution analysis can also be used to determine the star’s size.
Mebsuta is a cool G star, with a temperature around 4,600K.
Compare this with the Sun, another G-type star, which has a photospheric surface temperature of 5,772K.
Despite this, Mebsuta’s large size leads to an overall luminosity which is just shy of 7,000 times that of the Sun.
This guide appeared in the January 2025 issue of BBC Sky at Night Magazine
