How did Vincent van Gogh create the swirling sky in The Starry Night?

Vincent van Gogh created the swirling sky in The Starry Night by relying on his memory, imagination, and drawings, as he was not permitted to paint in his bedroom at the Saint-Paul-de-Mausole asylum where he was staying.12

To achieve the painting's characteristic texture and movement, he employed an expressive style he had developed during his time in Paris. He applied paint directly from the tube onto the canvas, creating thick impasto—a technique where paint is applied in quantities that make it stand out from the surface. This method, combined with his vigorous use of line and dynamic forms, allowed him to render the night sky as roiling with chromatic blue swirls. While van Gogh generally preferred working from direct observation, his confinement at the asylum led him to involve himself more imaginatively in the drama of the elements, resulting in the visionary and turbulent sky seen in the work.234