The Bubble Nebula forms a distinct half-circle surrounding a massive and energetic star. As opposed to M27 and M57, the nebula in NGC7635 is caused by the massive solar forces of the central star forcing the surrounding gases into a shell. These gases are then energized by the light from the central star, causing it to glow. The Bubble Nebula is surrounded by a vast area of nebulosity, partially visible above and to the left of the bubble in this photograph . The Bubble Nebula is a close neighbor to the M52 open cluster.