Imagine a camera-flash in space ... it's an expanding sphere of light.
In this photo we have a star which has exploded. We are seeing the light-burst traveling outwards in all directions as it illuminates dust and gas previously blown-off by the star.
Size comprehension -
our entire Solar System would fit easily inside the red aura around the star, look again at the dates on the images and remember that light travels at roughly 186,000 miles per second and these pics span 6 months at that speed.
