On Saturday, 18 November 2017 12:27:59 UTC-5, Razzmatazz wrote:
Just before winter sets in the outer arms of the Milky Way pass overhead. Embedded in them are regions of star formation and star death. M76 is a Planetary Nebula where the central star has shed its outer atmosphere shedding its hydrogen (the bright red areas) and oxygen (blue areas) into a shell, which is expanding into the surrounding space.
https://www.astromart.com/common/ima...7.jpg&caption=
Which colour for double-ionized oxygen is real? Most shots I've seen, it's been green, but it's blue here.