How often are moon phases updated? ▼
Moon phase data updates in real time. The current phase, illumination percentage, and moon age are calculated using precise astronomical algorithms and refresh automatically every 1 minute.
How accurate are the moon phase calculations? ▼
Our calculations are based on established astronomical algorithms used by NASA and other space agencies. The precision is within minutes for phase timing and 0.1% for illumination values.
What do the different moon phase emojis represent? ▼
Each emoji represents a specific lunar phase:
🌑 New Moon (0% illuminated)
🌒 Waxing Crescent (1-49% illuminated)
🌓 First Quarter (50% illuminated)
🌔 Waxing Gibbous (51-99% illuminated)
🌕 Full Moon (100% illuminated)
🌖 Waning Gibbous (51-99% illuminated)
🌗 Last Quarter (50% illuminated)
🌘 Waning Crescent (1-49% illuminated)
How is moon illumination percentage calculated? ▼
Illumination percentage represents the fraction of the Moon's disk that is illuminated by the Sun as seen from Earth. It's calculated based on the angular separation between the Sun and Moon using the formula: (1 - cos(elongation)) / 2, where elongation is the Moon-Sun-Earth angle.
What is the difference between a synodic and sidereal month? ▼
Synodic month (29.53 days) is the time between two consecutive new moons — this determines moon phases.
Sidereal month (27.32 days) is the time Moon takes to orbit Earth relative to fixed stars.
The difference occurs because Earth is also moving around the Sun.
Why does the Moon look different in the Southern Hemisphere? ▼
The Moon appears upside down in the Southern Hemisphere!
This happens because observers in different hemispheres are looking at the Moon from opposite perspectives. Think of standing on opposite sides of a globe — what appears «up» to one person appears «down» to the other.
• Northern Hemisphere: Waxing moon illuminates from right to left
• Southern Hemisphere: Waxing moon illuminates from left to right
• Equator: The Moon appears to «lie on its side»
The Moon's phases are the same globally, but their orientation changes with latitude!