Astronomy Calculators
Find sunrise times, sunset times, dawn periods, and moon phases for any location on Earth with our free astronomy calculators. These tools use standard solar position algorithms and your geographic coordinates to deliver accurate results for photography planning, outdoor activities, religious observances, and general curiosity about celestial events.
Sunrise Calculator
Find the exact sunrise time for any location and date based on geographic coordinates.
Sunset Calculator
Find the exact sunset time for any location and date based on geographic coordinates.
Dawn Calculator
Calculate civil, nautical, and astronomical dawn times for any location and date.
Moon Phase Calculator
Find the current moon phase and view a lunar calendar with full and new moon dates.
How to Choose the Right Astronomy Calculator
The sunrise calculator and sunset calculator are paired tools that tell you when the sun appears above and drops below the horizon at your location on any given date. Use the sunrise calculator for early morning planning such as photography golden hour, jogging schedules, or religious prayer times that depend on sunrise. Use the sunset calculator for evening event planning, outdoor lighting schedules, or determining how much daylight remains.
The dawn calculator goes deeper into the pre-sunrise period by computing three distinct twilight thresholds: civil dawn (sun 6 degrees below the horizon, enough ambient light for most outdoor activities), nautical dawn (sun 12 degrees below, the horizon becomes visible at sea), and astronomical dawn (sun 18 degrees below, the sky is no longer completely dark). Photographers, astronomers, and pilots all rely on these distinctions.
The moon phase calculator shows the current lunar phase, illumination percentage, and dates of upcoming full moons and new moons. It is valuable for astrophotography planning, fishing and hunting schedules influenced by moonlight, gardening traditions tied to lunar cycles, and anyone who simply wants to know whether tonight will be bright or dark.
Understanding Solar and Lunar Cycles
Sunrise and sunset times depend on three main factors: your geographic latitude, the date (which determines the sun's declination), and your longitude within your time zone. At the equator, day length stays close to 12 hours year-round. As you move toward the poles, seasonal variation increases dramatically. Above the Arctic Circle (66.5 degrees north) and below the Antarctic Circle, the sun can stay above or below the horizon for 24 continuous hours during the summer and winter solstices.
Twilight is the period when the sun is below the horizon but its light still illuminates the sky. Civil twilight occurs when the sun is between 0 and 6 degrees below the horizon and provides enough light for most outdoor activities without artificial lighting. Nautical twilight extends from 6 to 12 degrees below the horizon, during which the horizon at sea is still visible. Astronomical twilight extends from 12 to 18 degrees, and once the sun passes 18 degrees below the horizon, the sky is considered fully dark for observational astronomy.
The moon completes one full cycle of phases approximately every 29.53 days, known as a synodic month. The eight principal phases are new moon, waxing crescent, first quarter, waxing gibbous, full moon, waning gibbous, third quarter, and waning crescent. The phases result from the changing angle between the sun, Earth, and moon as the moon orbits Earth. A new moon occurs when the moon is between the sun and Earth, and a full moon occurs when Earth is between the sun and moon.
Atmospheric refraction bends sunlight as it passes through Earth's atmosphere, causing the sun to appear above the horizon when it is geometrically still below it. This effect adds roughly 2 to 4 minutes to the visible day at mid-latitudes. All accurate sunrise and sunset calculators account for atmospheric refraction using a standard correction of approximately 0.833 degrees, though actual refraction varies with temperature, pressure, and humidity.
Frequently Asked Questions
How accurate are the sunrise and sunset times?
Our calculators use the standard solar position algorithm, which is accurate to within one to two minutes for most locations and dates. The main source of variation is atmospheric refraction, which depends on local weather conditions like temperature, pressure, and humidity. The standard refraction correction of 0.833 degrees is applied, which works well under typical conditions. At extreme latitudes near the Arctic or Antarctic circles, accuracy can decrease slightly during periods when the sun barely rises or sets.
What is the difference between civil, nautical, and astronomical dawn?
These three types of dawn are defined by how far the sun is below the horizon. Civil dawn begins when the sun is 6 degrees below the horizon, and there is enough light for most outdoor activities. Nautical dawn begins at 12 degrees below, when the horizon becomes visible at sea for navigation. Astronomical dawn begins at 18 degrees below, when the faintest stars start to disappear. Each type serves different practical purposes, from daily routines (civil) to maritime navigation (nautical) to telescope observations (astronomical).
How do I find sunrise and sunset times for my location?
Enter your latitude and longitude into the sunrise or sunset calculator along with the date you are interested in. If you do not know your coordinates, you can look them up using an online map service or enable location access on your device. The calculator applies the solar position equations for your coordinates and date, then adjusts for your time zone and standard atmospheric refraction to give you the local sunrise or sunset time.
Why do sunrise and sunset times change throughout the year?
The change is caused by Earth's axial tilt of approximately 23.4 degrees. As Earth orbits the sun, the tilt causes the sun's apparent path across the sky to shift north and south. During summer in the Northern Hemisphere, the sun rises earlier, sets later, and climbs higher in the sky, producing longer days. During winter, the opposite occurs. At the equinoxes in March and September, day and night are approximately equal everywhere on Earth.
What determines the current moon phase?
The moon phase depends on the relative positions of the sun, Earth, and moon. As the moon orbits Earth roughly every 29.53 days, the angle of sunlight hitting the moon changes from our perspective. When the moon is between the sun and Earth, the lit side faces away from us and we see a new moon. When Earth is between the sun and moon, the full lit face is visible as a full moon. The gradual transitions between these positions create the crescent, quarter, and gibbous phases.