礁湖星云1654

礁湖星云是乔瓦尼·巴蒂斯塔·奥迪耶纳在1654年之前发现的，并且是北半球中纬度地区以肉眼隐约可以看见的两个恒星形成区之一。用双筒望远镜观察，它看起来是一个明显的椭圆形云状斑块，并有明确的核心。

特征

估计礁湖星距离地球在4,000〜6,000光年。在天球上，它的跨度为90′X 40′，也就是说实际的尺寸是110 X 50光年。像许多星云一样，在长时间曝光的彩色照片中，它看起来是粉红色的，但人眼通过双筒望远镜或望远镜观察时是灰色的，这是因为人类的视觉感知在低光照下对颜色的敏感度很差。这个星云中有许多包克云球（黑暗、坍塌的原恒星物质），其中最突出的被E.E.巴纳德收录在他编辑的目录中，编为B88、B89和B296。

礁湖星云还包含一个由一颗O型星引起的漏斗状或龙卷风状结构，在星云表面辐射出紫外线，加热和电离气体。礁湖星云的中心还包含一个由约翰·赫歇尔命名，称为沙漏星云的结构；不要将它与苍蝇座的沙漏星云混淆在一起。在 2006年，在沙漏星云中检出最初的4个赫比格-哈罗天体，其中一个就是HH 870。这提供了恒星是通过吸积作用形成的第一个证据。

科幻小说

在星际大争霸（2004年电视连续剧）有两季家的剧情，以礁湖星云做确认地球的指标。

礁湖星云 (科幻)

The Lagoon Nebula (catalogued as Messier 8 or M8, NGC 6523, Sharpless 25, RCW 146, and Gum 72) is a giant emission nebula with an H II region located in the constellation Sagittarius. Discovered by Giovanni Hodierna in 1654, it is one of only two star-forming nebulae faintly visible to the naked eye from mid-northern latitudes (the other being the Orion Nebula).

Characteristics

Located approximately 4,000–6,000 light-years from Earth, the nebula spans 110 by 50 light-years (appearing as 90' by 40' in Earth's sky). While appearing pink in long-exposure photographs, it typically appears gray when viewed through binoculars or telescopes due to the human eye's limited color sensitivity in low-light conditions. The nebula contains the young open cluster NGC 6530 within its structure.

• The Lagoon Nebula features several distinctive structures, including:
• Multiple Bok globules cataloged by E. E. Barnard (B88, B89, and B296)
• A funnel-shaped structure formed by ultraviolet radiation from a hot O-type star

The centrally-located Hourglass Nebula (named by John Herschel), distinct from the Engraved Hourglass Nebula in Musca

Observations in 2006 revealed four Herbig–Haro objects within the Hourglass structure, providing direct evidence of ongoing star formation through accretion processes.