C. Gieser

When a young star ejects jets of gas, they slam into the surrounding cloud like a fist into a pillow. At the impact site, the gas is compressed and heated — creating a shock wave. In this hot zone, atoms and simple molecules collide and assemble into larger compounds, known as complex organic molecules.

In the cold gas cloud where a star is born, chemistry sleeps. Molecules barely collide, reactions stall. But when a charged particle zips through the cloud, it knocks electrons off atoms — ionizing them. That's how active ions appear in a dormant cloud, ready to build new molecules.