A laser scanner optically scans and measures an environment, the laser scanner having a base resting in the stationary reference system of the laser scanner, a measuring head rotatable about a vertical axis relative to the base, a measuring head rotatable relative to the base about a vertical axis, a motor supported in the measuring head, the motor having a motor shaft and a gear which, when driven by the motor by the motor shaft, turns the measuring head relative to the base, the gear being configured as a planetary gear.