Emission nebula NGC 2264, optical image. North is at right. NGC 2264 is an emission nebula, where radiation from nearby hot young stars ionises the hydrogen gas in it, causing red light to be emitted. It contains the Cone nebula, a small dark wedge in the bright red area at centre left, which houses embryonic stars in its dense clouds of gas and dust. Another component is the Fox Fur nebula, a region where blue/white light is also seen due to the blue light from stars being reflected by the nebula. The largest star within this nebula is S or 15 Monocerotis (centre). NGC 2264 lies about 2600 light years from Earth, in the constellation Monoceros.