What is a ghost nebula?

The Ghost Nebula is a diffuse nebula located in Orion, which is 1300 light-years away from the Earth. It looks like a black ghost floating in the fog. The ghost nebula, numbered NGC6369, was discovered by British astronomer William Herschel when he observed Ophiuchus with a telescope in the18th century. This nebula has the circular appearance of a planet, and it is also very dark, so it is nicknamed the ghost nebula. The bright variable V380 inside Orion illuminates this nebula. These cold gases and dust are so dense that they completely block the passage of light. The stars in this dark cloud may be dense. This dark cloud is a dense gas and dust cloud called bok globule.

The Little Ghost Nebula is located in Ophiuchus, 2000 light years away from the solar system. The gas is splashing at a speed of about 24 km/s, and the diameter of the air mass has reached 1 light-year. The middle part of the blue-green color is composed of gas, which is the result of strong ionization of the red giant under the action of ultraviolet light. The outside of the air mass is weakly affected by ultraviolet rays, so the outside color of the air mass is close to yellow and orange.