Astronomy Picture of the Day

Explanation: This huge ball of stars predates our Sun. Long before mankind evolved, before dinosaurs roamed, and even before our Earth existed, ancient globs of stars condensed and orbited a young Milky Way Galaxy. Of the 250 or so globular clusters that survive today, M3 is one of the largest and brightest, easily visible in the Northern hemisphere with binoculars. M3 contains about half a million stars, most of which are old and red. The existence of young blue stars in M3 once posed a mystery, but these blue stragglers are now thought to form via stellar interactions.

這個龐大的球狀星團比太陽還古老。 遠在人類出現之前、比恐龍漫遊地球的年代古老，甚至比地球存在還早時，這些古老的恆星就已聚結成團，繞著年輕的銀河系運行。 目前在銀河系中孑遺下來的200多個球狀星團之中，M3是最大且是最亮的數個球狀星團之一，在北半球，用雙筒望遠鏡即輕易可見。 M3擁有約50萬顆成員星，其中大部分是又老又紅。 它內部的年輕泛藍恆星，曾是難解的謎團，不過，這些藍掉隊星目前咸認是因為恆星交互作用而形成的。