APOD: 2020 July 21 - Iron in the Butterfly Nebula

Good morning, Rallypoint. Today's Astronomy Picture of the Day (APOD) is titled "Iron in the Butterfly Nebula." The Butterfly Nebula (NGC 6302) lies some 4,000 light years away in the constellation Scorpius. What allows us to suspect that iron is there? Light. In physics, an emission spectrum refers to the electromagnetic energy emitted by a particle (e.g. an atom) when it is converted from a higher energy state to a lower one. In the case of the Butterfly Nebula, its emission spectrum indicates the presence of iron. Thanks to this Hubble image, we can see the (red) iron quite clearly.