Britannica Sources used in this answer

How does FAST aim at different parts of the sky even though its main dish is fixed?

Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

Radio telescope Lovell Telescope, a fully steerable radio telescope at Jodrell Bank, Macclesfield, Cheshire, England.

Although the main dish of the Five-hundred-metre Aperture Spherical Telescope (FAST) is fixed within a natural depression, it can observe different parts of the sky—specifically within 40 degrees of the zenith—through two primary mechanisms:

Changeable Surface: The shape of the telescope's spherical reflecting surface is adjustable, allowing it to be deformed to focus incoming radio waves effectively.1
Movable Feed Cabin: The feed cabin, which serves as the focal point where radio waves are collected, is suspended from six cables. This cabin moves dynamically around the surface of the dish to track celestial sources as they move across the sky.1

These combined technologies allow FAST to maintain high-resolution observations despite the immobility of its massive 500-metre structure.1