Emission nebula IC 4606. Optical image of the large emission nebula IC 4606 (pink) around the star Antares (Alpha Scorpii, white area). Antares lies 520 light years from Earth in the constellation Scorpius. It is a red supergiant some 700 times larger than the Sun. IC 4606 glows as the hydrogen gas it contains is ionised by radiation from the stars within it. At lower right is the globular star cluster M4. This is a huge ball of hundreds of thousands of stars. It is not part of the Antares association, lying some 7500 light years from Earth.