Omega Nebula

M17 in Sagittarius is one of the youngest and most massive star-forming regions in the Milky Way, sitting almost directly along the line of sight to the Galactic centre. Its glowing core has earned it more nicknames than most objects in the sky — the Swan, the Checkmark, the Horseshoe, the Lobster — for a shape produced by NGC 6618, a cluster of roughly 35 hot O and B stars barely a million years old, buried behind enough dust to hide most of its members from view. At around 5,500 light-years, M17 lies deep in the Sagittarius star clouds, which is also why the surrounding field is this crowded. From Edinburgh’s latitude it never climbs past about 18° above the southern horizon.