Sunrise & Sunset Calculator

How Does the Sunrise & Sunset Calculator Work?

This Sunrise & Sunset Calculator uses precise astronomical algorithms to compute the sun’s apparent position for any latitude, longitude, and date. It shows local or UTC times for sunrise, sunset, and day length.

• Sunrise/Sunset: When the top edge of the sun crosses the horizon (solar elevation -0.833°)
• Day Length: The interval between sunrise and sunset
• Civil Twilight: When the sun is 6° below the horizon
• Time Zone: Choose local (auto-detected) or UTC output

Common Applications

The Celestial Mechanics Behind Sunrise and Sunset

The daily rhythm of sunrise and sunset is one of the most fundamental experiences on Earth, yet the science behind it involves a beautiful and complex celestial dance. A Sunrise & Sunset Calculator must account for several key astronomical factors to achieve its accuracy.

1. Earth’s Rotation

The most basic cause of sunrise and sunset is the Earth’s rotation on its axis. Our planet spins counter-clockwise (when viewed from above the North Pole) at a speed of about 1,670 kilometers per hour at the equator. This rotation is what makes the sun, moon, and stars appear to travel across the sky from east to west. Sunrise occurs when your specific location on the globe rotates into view of the sun, and sunset occurs when it rotates away into shadow.

2. Earth’s Axial Tilt

This is the most critical factor for why sunrise and sunset times change throughout the year and why we have seasons. The Earth’s axis is not perpendicular to its orbital plane; it’s tilted by approximately 23.5 degrees.

• Summer Solstice: When your hemisphere is tilted toward the sun, you experience the longest day of the year. The sun takes a higher, longer path across the sky, resulting in an early sunrise and a late sunset.
• Winter Solstice: When your hemisphere is tilted away from the sun, you experience the shortest day of the year. The sun travels a lower, shorter arc, leading to a late sunrise and an early sunset.
• Equinoxes: During the spring and autumn equinoxes, the Earth’s tilt is neither toward nor away from the sun, resulting in nearly equal day and night lengths across the globe.

3. Earth’s Orbit Around the Sun

The Earth revolves around the sun in an elliptical (oval-shaped) orbit, completing one full revolution in about 365.25 days. While the axial tilt is the primary driver of the seasons, the elliptical orbit also contributes to slight variations in the length of the solar day, a concept captured by the “Equation of Time.”

A precise Sunrise & Sunset Calculator integrates all these variables—rotation, axial tilt, and orbital position—to determine the exact moment the sun’s disk will appear to cross the horizon for any given latitude and longitude on any specific day of the year.

More Than Just Day and Night: A Guide to Twilight

The transition between day and night is not instantaneous. The period after sunset and before sunrise, when the sky is still partially illuminated by scattered sunlight, is known as twilight. Our calculator shows the times for Civil Twilight, but there are actually three distinct phases, each defined by the sun’s angle below the horizon.

1. Civil Twilight

• Sun’s Position: 0° to 6° below the horizon.
• Description: This is the brightest phase of twilight. Shortly after sunset, there is generally enough natural light to continue most outdoor activities without artificial lighting. The horizon is clearly visible, and the brightest stars and planets, like Venus, become apparent. This period is often what people refer to as “dusk.”

2. Nautical Twilight

• Sun’s Position: 6° to 12° below the horizon.
• Description: During this phase, the horizon becomes difficult to distinguish, but the outlines of objects on the ground may still be visible against the sky. Historically, sailors could still take reliable navigational readings on the stars because both the horizon and the stars were visible. Most general outdoor activity requires artificial light by this point.

3. Astronomical Twilight

• Sun’s Position: 12° to 18° below the horizon.
• Description: To the casual observer, the sky appears fully dark. However, there is still a faint, almost imperceptible glow from scattered sunlight in the upper atmosphere. This faint light can interfere with astronomical observations of the faintest deep-sky objects, like nebulae and distant galaxies. The sky is only truly “dark” for astronomical purposes when the sun is more than 18° below the horizon.

For Photographers: Mastering the Golden and Blue Hours

For photographers, the times provided by a Sunrise & Sunset Calculator are more than just data—they are the key to unlocking the most magical light of the day. The periods around sunrise and sunset create unique lighting conditions that are highly prized for their aesthetic qualities.

The Golden Hour

The “Golden Hour” is the period shortly after sunrise and shortly before sunset. During this time, the sun is very low in the sky, and its light has to travel through more of the Earth’s atmosphere. This has two effects:

1. Soft, Diffused Light: The atmosphere scatters the blue and violet light, resulting in a light that is predominantly warm, soft, and golden-red in color.
2. Long Shadows: The low angle of the sun creates long, dramatic shadows that can add depth and texture to a photograph.

This light is ideal for portrait and landscape photography because it is much more flattering and less harsh than the direct overhead sun of midday.

The Blue Hour

The “Blue Hour” occurs during the deeper phases of twilight (typically civil and nautical twilight), just before sunrise and just after sunset. The sun is below the horizon, so there is no direct sunlight. The sky is filled with a deep, saturated blue light that is indirect and incredibly soft. This is a perfect time for capturing cityscapes, as the ambient blue light can be balanced beautifully with the warm, artificial lights of buildings and streets.

By using a reliable Sunrise & Sunset Calculator, photographers can precisely plan their shoots to be on location and ready to capture these fleeting but spectacular moments of natural light.

The Equation of Time: Why Solar Noon Shifts

Many people assume that the sun is at its highest point in the sky (an event called solar noon) at exactly 12:00 PM on their clock. Similarly, they might assume that the earliest sunset occurs on the winter solstice, the shortest day of the year. Both of these assumptions are incorrect, due to a concept known as the Equation of Time.

The Equation of Time describes the discrepancy—ranging up to about 16 minutes—between the time on our clocks (mean time) and the time measured by the actual position of the sun (apparent solar time). This difference arises from two main factors:

1. The Earth’s Elliptical Orbit: Our planet moves faster in its orbit when it is closer to the sun (in January) and slower when it is farther away (in July). This changing speed affects how long it takes for the sun to appear to return to the same point in the sky each day.
2. The Earth’s Axial Tilt: The 23.5° tilt of the Earth means that the sun’s apparent path across the sky changes throughout the year. This affects the east-west component of the sun’s apparent motion, contributing to the time difference.

Because of this discrepancy, solar noon can occur several minutes before or after 12:00 PM. This also explains why the earliest sunset for most mid-latitude locations in the Northern Hemisphere actually occurs in early December, a couple of weeks before the winter solstice, while the latest sunrise occurs in early January, a couple of weeks after the solstice. A high-quality Sunrise & Sunset Calculator incorporates these complex calculations to provide accurate times, not just simple averages.