Apropos of nothing*, I decided today to write about a red and green nebula. I just needed to pick one. Those shouldn't be too hard to find! Gas clouds contain hydrogen and oxygen, and those glow at the right colors. So I hit the search engines with the obvious phrase "red green nebula" and took a look at the images that came back.
… and immediately laughed out loud. Almost all the images returned came from far-infrared observatories like WISE and Spitzer Space Telescope; it had momentarily slipped my mind that the colors they use in their images are predominantly red and green. I was expecting visible light images! But that's OK, colors are colors and so I poked around what was there to find something fun to write about.
This one came up near the top, and I have to admit I chose it for a couple of reasons besides the colors. But here, let's take a look first:
The huge shell of gas and dust that make up RCW 120, seen here in the far infrared by the Spitzer Space Telescope. Credit: NASA/JPL-Caltech/GLIMPSE-MIPSGAL Teams
Wow! That's RCW 120, in an image taken by Spitzer in 2011. It’s a ...