仙王座中的象鼻星云

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）撰写的简短说明。

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.

说明：就像银河系「如此故事」中的插图一样，象鼻星云（Elephant's Trunk Nebula）蜿蜒穿过位于高远仙王座（Cepheus）星座（constellation）中的发射区和年轻星团（young star cluster）复合体 IC 1396。这个也被称为 vdB 142 的宇宙象鼻长度超过 20 光年（light year）。这张精细的望远镜图像展示了该区域中丰富的明亮后掠脊，以及冷星际尘埃（interstellar dust）和气体的囊状结构。然而，这些暗色的卷须状云团包含了恒星形成（star formation）的原材料，并隐藏着其中的原恒星（protostar）。IC 1396 复合体距离我们近 3,000 光年，在天空中覆盖了大片区域，跨度超过 5 度。不过，这幅类似长鼻动物的图像所展示的视场（field of view）宽度接近 1 度。这比两个满月（full moon）的角大小（angular size）略小一些。

Explanation: Like an illustration in a galactic Just So Story, the Elephant's Trunk Nebula winds through the emission region and young star cluster complex IC 1396, in the high and far off constellation of Cepheus. Also known as vdB 142, this cosmic elephant's trunk is over 20 light-years long. The detailed telescopic view features the bright swept-back ridges and pockets of cool interstellar dust and gas that abound in the region. But the dark, tendril-shaped clouds contain the raw material for star formation and hide protostars within. Nearly 3,000 light-years distant, the relatively faint IC 1396 complex covers a large region on the sky, spanning over 5 degrees. Top to bottom this proboscidean-like rendition reaches across an almost 1 degree wide field of view, though. That's a little less than the angular size of 2 full moons.