Sadr (pronounced “sadder” or “sudder”) is the central star of
the beautiful Northern Cross asterism of Cygnus the Swan, which rises in the East this month and then gradually ascends to the top of the sky. The name comes from an ancient Arabic phrase — “the hen’s breast.”
With a temperature around 6,500 degrees Kelvin, this yellow supergiant star may not be much hotter than our Sun, but it is tremendously luminous, shining around 65,000 times as bright. Found at the northern end of the Great Rift, a dust lane that appears to divide the Milky Way, Sadr lies in a region of glowing interstellar clouds that may contain numerous star nurseries. It is
believed that this dying star is around 1,500 light years away and
once was twelve times the size of the Sun. Look below the “crossbeam”
star and you’ll find the open star cluster of M29.