The Cygnus Loop appears as a faint ring of glowing gases about three degrees across (six times the diameter of the full moon), located in the northern constellation Cygnus the Swan.
天鹅座的Loop看起来是个由炽热气体形成的模糊光环(满月直径的6倍大小),坐落在天鹅座星群的北方。
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One of the best cases known goes by the name Cygnus X-1, because it was the first X-ray source discovered in the constellation Cygnus the Swan.