Introducing the citizen 'tsuki yomi' radio controlled moon phase the world’s first light powered radio controlled moon phase movement. To celebrate the 30th anniversary of the first citizen radio controlled watch we are debuting the world’s first fully analogue moon phase function for light powered watches. The tsuki yomi collection directly translating to “reading the moon” features a new radio controlled eco drive cal. H874 movement that provides ±15 seconds accuracy per month, revolutionary proprietary super titanium™ material and artfully crafted moon pattern dials. Based on a unique mathematical formula developed by citizen called “luna program”, the watch calculates the phase of the moon each day from signals received from multi band radio transmitters. The phase of the moon at the six o’clock position is then automatically adjusted and displayed. With a striking blue pattern of the moon’s surface on the dial paired with a black outer ring, and date display at the 4 o’clock position. Sustainably powered by any light, including moon light, with our proprietary eco drive technology, this timepiece never needs a battery.