If you look closely, you might be able to picture the face of Santa Claus in these festive pink clouds. You’re seeing two overlapping glowing nebulas called NGC 248 in the Small Magellanic Cloud (SMC), a small galaxy that orbits the Milky Way like a planet orbit the sun. Intense radiation from hot young stars in the center of each nebula cause the hydrogen gas to fluoresce a pretty holiday red. It’s a jolly big Santa, spanning 20 light years wide by 60 light years long. Multiply those numbers by 6 trillion to get the size in miles.
The image is part of a study called Small Magellanic Cloud Investigation of Dust and Gas Evolution (SMIDGE). Astronomers are using Hubble to probe the Milky Way satellite to understand how dust is different in galaxies that have a far lower supply of elements heavier than hydrogen and helium needed to create dust. The Small Magellanic Cloud has between a fifth and a tenth of the amount of heavy elements that the Milky Way does. Back when the universe was a young pup, most everything was hydrogen and helium. The heavier elements had to be cooked up in the cores of generations of stars. That’s why there’s a lot more dust — made of these heavier materials that combined to form minerals — nowadays compared to the primal days.
Good thing, too. You can’t form an Earth from gas, you need solid stuff. We might sweep it away or vacuum it up, but for scientists, dust is key to understanding the history of the galaxy. Santa brings toys to all good girls and boys and to studious astronomers, too.