Menkent (stars.astro.illinois.edu)MENKENT (Theta Centauri). Centaurus is dominated by its two brightest stars, Rigil Kentaurus (Alpha Centauri, third brightest star in the sky and the nearest star to the Earth) and first magnitude Hadar (Beta Centauri). Though these two shine brilliantly to the lucky residents of the southern hemisphere, neither is visible from mid-northern latitudes, so if those that live there wish to know Centaurus, they must begin with the third brightest star in the constellation, Menkent, to which is assigned the rather lowly letter Greek letter Theta (Gamma Centauri rather oddly coming in second).