M74：一个宏象旋涡结构

探索宇宙（universe）！每天都会展示一张我们迷人宇宙的不同图像或照片，并附上一段由专业天文学家（astronomer）撰写的简短解释。

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

解释：如果不是最宏伟的，那么这个旋涡星系（spiral galaxy）至少也是最上镜的星系之一。M74是一个拥有约1000亿颗恒星（star）的岛宇宙（island universe），位于双鱼座（Pisces）方向，距离我们3200万光年（light-year），呈现出华丽的正向（face-on）视角。M74被归类为Sc型星系（Sc galaxy），其宏观图像（grand design）中优美的旋臂（spiral arm）由明亮的蓝色星团（star cluster）和暗色的宇宙尘（cosmic dust）带勾勒出来。这张清晰的合成图像由哈勃空间望远镜（Hubble Space Telescope）的存档图像构建而成。它横跨M74约30000光年，包含了记录氢原子发射的曝光数据，突显了该星系大型产星区（star-forming region）发出的微红光芒。

Explanation: If not the most grand, then this spiral galaxy is at least one of the most photogenic. An island universe of about 100 billion stars, 32 million light-years away toward the constellation Pisces, M74 presents a gorgeous face-on view. Classified as an Sc galaxy, the grand design of M74's graceful spiral arms are traced by bright blue star clusters and dark cosmic dust lanes. Constructed from archival images, this sharp composite is from the Hubble Space Telescope. Spanning about 30,000 light-years across the face of M74, it includes exposures recording emission from hydrogen atoms, highlighting the reddish glow of the galaxy's large star-forming regions.