The Crab Nebula is a supernova in the constellation of Taurus. It was named in the late 1800s when early telescopes made it look like a crab. It is not visible to the naked eye The nebula lies in the Perseus Arm of the Milky Way. It emits pulses of radiation from gamma rays to radio waves, and is generally the brightest persistent source in the sky. Some sources consider the Crab Nebula to be an example of both a pulsar wind nebula as well as a supernova remnant, based on the different sources of energy production and behaviour.

The Orion Nebula sits in the Milky Way, in the constellation of Orion. One of the brightest nebulae, at night it can be visible to the naked eye. Orion is made up of clouds of gas, dust, stars, and reflection nebulae. It is part of a much larger nebula that is known as the Orion Molecular Cloud Complex, where stars are forming throughout, but most of the young stars are concentrated in dense clusters like the one illuminating the Orion Nebula.