Trifid Nebula. True-colour optical image derived from UK Schmidt plates of the Trifid Nebula (M20, NGC 6514) in the constellation Sagittarius. The red part of the nebula is a glowing cloud of hydrogen gas ionised and lit up by a bright central star. It is crossed by dark lanes of interstellar dust which absorb and scatter the emitted light. It is believed that new stars are forming in M20 especially in the brightest middle region. The blue area is a reflection nebula, a cloud of cooler dust and gas that reflects the light of the bright star in its centre. The Trifid Nebula is about 6500 light years from Earth.