Emission nebula NGC 6870 (optical image). This faint nebula lies about 6000 light years from the earth in the constellation Vulpecula. It is a region of star formation, and glows red as hydrogen gas is ionised by radiation from the hot young stars within it. This nebula is lit by the central star cluster known as NGC 6823, which is about two million years old. These stars are carving out the intricate structure of the nebula, including the prominent dark rod (centre).