As the surface of the Bubble Nebula’s shell expands outward, different gasses emit different colors: oxygen irradiated enough emits blue light in the bubble near the star, while the combined light of hydrogen and nitrogen form the pillars of yellow. Hubble’s Wide Field Camera 3 (WFC3) imaged the nebula in visible light with unprecedented clarity in February 2016. The colors — blue for oxygen, green for hydrogen and red for nitrogen — help astronomers understand the geometry and dynamics of this complex system.
