Interactive 3D planet model generated by code, with adjustable sea level and sun position

Prompt

i asked opus 5.5 to build me a planet.

not a picture of a planet. a whole planet.

it wrote a single html file. no libraries, no images, no 3d models. every ocean, every mountain and every city light is math, generated live in your browser.

then i started playing with it.

drag it and it spins. raise the sea level and watch continents drown. move the sun and watch the cities switch on at night.

hit "new planet" and it invents a new world. it even names it.

a year ago this was a semester project for a graphics student.

now it's a prompt.