1. an instrument with a movable mirror that reflects sunlight in a fixed direction
Usage: scientific; astronomy

Examples

• The heliostat tracked the sun’s movement throughout the day.
• Scientists used a heliostat to direct sunlight into the laboratory.
• The solar power plant employed hundreds of heliostats to focus light.
• A heliostat requires precise calibration to maintain accurate sun tracking.
• The observatory’s heliostat allowed researchers to study solar phenomena safely.
• Ancient astronomers developed early versions of the heliostat for observations.