Moon Phase Today Calculator
Track the current moon phase and upcoming lunar events
About this tool: Our calculator uses astronomical algorithms to accurately determine the current moon phase based on your selected date.
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Please select a date to view the moon phase.
Illumination:
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Age in Cycle:
-- days
Next Full Moon:
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Next New Moon:
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Lunar Phase Calendar
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Understanding Moon Phases
Primary Moon Phases
- New Moon - Moon is between Earth and Sun (0% illuminated)
- First Quarter - Right half of moon visible (50% illuminated)
- Full Moon - Complete lunar disk visible (100% illuminated)
- Last Quarter - Left half of moon visible (50% illuminated)
Intermediate Phases
- Waxing Crescent - Between new and first quarter
- Waxing Gibbous - Between first quarter and full
- Waning Gibbous - Between full and last quarter
- Waning Crescent - Between last quarter and new
The lunar cycle takes approximately 29.5 days to complete (from one new moon to the next). This is known as a synodic month. The moon's appearance changes because we see different amounts of the illuminated portion as it orbits Earth.
The Science Behind Moon Phases
Illumination Mechanics
The moon doesn't produce its own light but reflects sunlight. Half of the moon is always illuminated by the sun (except during lunar eclipses). The phase we see depends on the relative positions of the Earth, moon, and sun. This creates the cycle of phases we observe from Earth.
Libration Effect
Though the moon always keeps the same face toward Earth, we can actually see slightly more than 50% of the lunar surface over time due to libration - a slight wobbling motion. This allows us to peek around the edges of the moon's visible hemisphere.
Lunar Distance Variations
The moon's orbit is elliptical, not perfectly circular. At perigee (closest approach), the moon is about 226,000 miles (363,300 km) from Earth. At apogee (farthest point), it reaches about 251,000 miles (405,500 km). This affects the apparent size of the moon as seen from Earth.
Did You Know? When a full moon occurs near perigee, we experience what's popularly called a "Supermoon" - where the moon appears up to 14% larger and 30% brighter than when at apogee.
Practical Applications of Moon Phase Data
Astronomical Photography
Photographers use moon phase information to plan shoots. Full moons provide excellent illumination for night landscapes, while crescent moons allow for capturing stars with partial lunar lighting. New moons offer the darkest skies for astrophotography.
Outdoor Activities
Hikers, campers, and outdoor enthusiasts often plan trips around moon phases. A full moon provides natural illumination for nighttime activities, while new moons offer optimal conditions for stargazing.
Tidal Predictions
Ocean tides are strongly influenced by the moon's gravitational pull. The highest (spring) tides occur during new and full moons when solar and lunar gravitational forces align. Understanding moon phases helps predict tidal patterns for fishing, boating, and coastal activities.
Cultural and Historical Events
Many cultures schedule festivals and celebrations around specific moon phases. For example, many lunar calendars define months by the cycle from one new moon to the next, and religious holidays like Easter, Passover, and Ramadan are timed using lunar calculations.
Frequently Asked Questions
How accurate is this moon phase calculator?
Our calculator uses standard astronomical algorithms that are accurate to within ±1 minute for dates between 1900-2100. The calculations account for the precise positions of Earth, moon, and sun based on their orbital mechanics.
Why does the moon sometimes appear orange or red?
The moon can appear orange or red when it's near the horizon due to Earth's atmosphere. When moonlight passes through more of our atmosphere (as happens near the horizon), blue light scatters away while red light passes through - the same phenomenon that causes reddish sunsets.
Is a Blue Moon really blue?
No, a "Blue Moon" refers to either the second full moon in a calendar month (modern definition) or the third full moon in a season with four full moons (traditional definition). The moon doesn't actually appear blue, though volcanic ash or smoke particles in the atmosphere can occasionally create a bluish tint.
Why can we sometimes see the moon during daylight?
The moon reflects enough sunlight to be visible even against a bright sky. When the moon is significantly separate from the sun in the sky (as happens with waxing crescent to waning gibbous phases), it can be seen during daylight hours if it's above the horizon.
How long does each moon phase last?
Since the complete lunar cycle takes approximately 29.5 days, each of the eight phases (new, waxing crescent, first quarter, waxing gibbous, full, waning gibbous, last quarter, waning crescent) lasts about 3.7 days on average. However, the exact duration can vary slightly due to the moon's elliptical orbit.