Scutum, constellation in the southern sky at about 19 hours right ascension and 10° south in declination. Its brightest star is Alpha Scuti, with a magnitude of 3.8. The star Delta Scuti is the prototype of a class of pulsating variable stars. In 1687 Polish astronomer Johannes Hevelius invented this constellation and called it Scutum Sobiescanium (Latin: “Sobieski’s Shield”) to commemorate the military victories of John III Sobieski, then king of Poland.