At the center of galaxy NGC 1068, located 47 million light-years away, lies a black hole hidden behind a dense veil of dust. But X-rays emitted by iron pierce through that veil. The Japanese satellite XRISM captured this glow and split it into colors, much as a prism splits sunlight.
It turns out that cold iron shines not in a thick wall of dust, but in tenuous gas scattered around. It's like expecting to see light from a lantern in fog, but instead the light comes from sparse water droplets in the air. Hot iron, on the other hand, races at enormous speeds — thousands of kilometers per second. Such a swift wind, like a hurricane, bursts out of the galaxy and carries matter away.
This wind may act as a brake: it sweeps away gas that could otherwise form new stars. In this way, the black hole at the galaxy's center controls its fate, preventing it from growing too quickly.
Iron glows in X-rays because electrons in its atoms jump from one orbit to another, emitting photons with energies around 6.4 thousand electron-volts — thousands of times more energetic than visible light.
In Stanislaw Lem's novel "Solaris," the planet's ocean emits mysterious signals; the X-ray glow of iron in NGC 1068 is also a kind of signal, but from a natural "ocean" of gas around a black hole.