A gassy cloud, also known as a NEBULA, is an interstellar cloud of dust, hydrogen, helium and other ionized gases. Nebulae are often star-forming regions, and can be seen in the night sky with the naked eye. They are made up of gas and dust particles that are held together by gravity. Gassy clouds are typically found in the outer reaches of galaxies, and can be composed of a variety of elements, including hydrogen, helium, carbon, nitrogen, oxygen, sulfur, and iron.