详细解释:n. 装煤麻袋, 煤袋(南十字星座中的一个暗星云)
详细解释：
Coal.sack
n.（名词）A dark nebula, one of the nearest to Earth, that appears in the southern Milky Way.煤袋：最接近地球的黑色星云之一，见于银河系南部A similar dark nebula in the Northern Hemisphere near the constellation Cygnus.黑色星云：北半球接近天鹅座的一种类似黑色星云