Point the right spectrograph at HD 189733b and the light that returns is a deep cobalt blue — the same blue you know from Earth's oceans seen from orbit. The resemblance is purely cosmetic, and one of the universe's crueller jokes.

The blue is not water. It is silicate — window glass — condensed from the atmosphere under extreme pressure and swept sideways at 5,400 miles per hour by wind systems that circle the planet without pause.

Astronomers first confirmed the colour through polarimetry in 2013 at La Silla Observatory. The finding was immediately arresting: here was a planet that looked, through a telescope, like it belonged in our own solar system.

JWST follow-up observations have since built a portrait of a world at the extreme edge of planetary physics — its atmosphere a soup of sodium, potassium, and vaporised iron, with carbon monoxide detected at wind speeds never recorded anywhere else.