Keith Horne

At the heart of galaxy NGC 4051 lies a black hole with a mass of 800,000 Suns. Around it swirls a blazing hot gas that shines brightly. This light doesn't reach us all at once: blue rays arrive first, then green, then red.

Steam over a boiling pot slightly tints the light of a flashlight: it blocks some colors and lets others through. That's roughly how we study the air of distant planets.