The Heart Nebula (IC 1805) is some 7500 light years away from Earth and is located in the Perseus Arm of the Galaxy in the constellation Cassiopeia. It was discovered by William Herschel on 3 November 1787. It is an emission nebula showing glowing ionized hydrogen gas and darker dust lanes. The brightest part of the nebula (a knot at its western edge) is separately classified as NGC 896, because it was the first part of the nebula to be discovered. The nebula's intense red output and its morphology are driven by the radiation emanating from a small group of stars near the nebula's center. This open cluster of stars, known as Collinder 26 or Melotte 15, contains a few bright stars nearly 50 times the mass of our Sun, and many more dim stars that are only a fraction of our Sun's mass. The Heart Nebula is also made up of ionised oxygen and sulfur gasses, responsible for the rich blue and orange colours seen in narrowband images. The shape of the nebula is driven by stellar winds from the hot stars in its core. The nebula also spans almost 2 degrees in the sky, covering an area four times that of the diameter of the full moon
The California Nebula (NGC 1499) is an intense hydrogen emission nebula located in the constellation Perseus. This iconic deep-sky object has been ignited by energetic starlight that has ionized its nebular gas composition. The most noticeable characteristics of this nebula are its striking resemblance in shape to the US state of California, and red color due to its hydrogen composition. It is almost 2.5° long on the sky and, because of its very low surface brightness, it is extremely difficult to observe visually.
The Elephant's Trunk Nebula is over 20 lightyears long and can be found running through IC 1396, a young star cluster embedded within a cloud of glowing, ionised gas in the Cepheus constellation. The Elephant's Trunk is composed of cool interstellar dust and gas, which blocks out light on its way to Earth and leaves behind a long, thin silhouette that gives the nebula its name (and makes it one of many nebulae that look like animals). Conversely, the hot radiation from these newborn stars blasts away the cosmic dust, ultimately destroying the ingredients that led to their formation in the first place. The IC 1396 complex is located about 3,000 lightyears away and covers an apparent width of over 10 full Moons in the sky.
