See tonight's moon as it looks from where you are, then scrub through the lunar cycle
Pick your city, read the phase and illumination, and watch the crescent lean the way it really leans at your latitude.
A physically lit moon, mapped with NASA Lunar Reconnaissance Orbiter surface data.
- Read the phase: phase name, lit fraction, and distance in kilometres for the moment you are looking at.
- Find it in the sky: a compass bearing and altitude, or a note that it is below the horizon.
- Travel in time: scrub forwards and back a whole day per step, and watch the terminator sweep across real craters.
- Set where you are viewing from: a city list, or "Use my location" for your exact latitude.
- The phase is computed, never animated: sun direction, illumination, and orientation come from real Sun and Moon geometry via astronomy-engine.
- The moon is tidally locked, as it is in life: the sphere holds still and the light moves around it.
- The scene frame is zenith-up: so a crescent from Melbourne leans differently from one in London, which is the point of the page.
- The maths is cross-checked: the lit fraction is verified against
Illumination()and the bright-limb angle against a closed-form Meeus solution implemented independently.
- Requires WebGL and a browser with JavaScript enabled.
- Surface relief is a NASA LRO normal map (albedo, normal, and roughness, 2048x1024 WebP).
- Your city is guessed from the browser timezone, so nothing is requested on load and no geolocation prompt appears until you ask for it.
MIT
Crafted by Matthew Blode