Asked by Jack Brown
We still aren’t sure why this nebula (MWC 922) has an almost perfectly symmetrical square shape but it’s thought that it’s thanks to the way in which MWC 922 ejects material and our relative viewing position.
This planetary nebula has a dying star at its core, which ejects gas and dust into its surrounding as it expires. It’s thought to be a bipolar nebula that spews out this material in two cones that emit from opposite sides of the star. From Earth we can see these two cones of ejecta from side-on, but they point in opposite directions. As the ejections of dust and gas are expelled in almost a 90-degree cone the nebula seems square.
Answered by Zoe Baily from the National Space Centre
Image Credit: NASA