Nebulae are enormous clouds of interstellar dust and gas. Depending on how they are illuminated, they can be called either reflection nebula or transmission nebula. As its name implies, a reflection nebula reflects the light from nearby stars. On the other hand, a transmission nebula emits light. A nearby star emitting light can cause the hydrogen atoms in a nebula to lose an electron. This causes the gas to become ionized, and as it cools back down, it glows.
This is an image captured from the Wide-field Infrared Survey Explorer (WISE) telescope. This space-born telescope has a 16 inch diameter and surveys light in the infrared wavelengths. The nebula at the center of this image is called LBN 114.55+00.22. In the lower left corner of the image is IRAS 23304+6147. This red star is nearing the end of its life. The supergiant variable star HIP 117078 is above and to the right of the nebula. Both stars are named after the satellites that cataloged them. Personally, I think that they need to come up with a better names for these stars and nebula.
The colors used in this image represent specific wavelengths of infrared light. Blue and cyan represent light emitted at wavelengths of 3.4 and 4.6 microns, which is predominantly from stars. Green and red represent light from 12 and 22 microns, respectively, which is mostly emitted by dust.
Image Credit: NASA/JPL-Caltech/WISE Team
