What is the difference between sunrise and civil dawn?

Sunrise is the moment when the upper edge of the sun's disc crosses the visible horizon. Civil dawn (also called civil twilight morning) begins earlier, when the center of the sun is 6 degrees below the horizon. During the period between civil dawn and sunrise, the sky is already bright with scattered light and most outdoor activities can be carried out without artificial lighting -- you can read, drive, and clearly see the surrounding landscape. The duration of this civil dawn period varies from about 20 minutes near the equator to over an hour at high latitudes near the solstice. In everyday speech, many people use the word "dawn" to mean the first light in the sky, which corresponds to civil dawn rather than actual sunrise.

Why does the earliest sunset happen before the winter solstice?

The earliest sunset in the Northern Hemisphere occurs around December 7 to 10, approximately two weeks before the winter solstice on December 21. This seems counterintuitive because the solstice is the shortest day of the year. The explanation is the equation of time, which shifts solar noon relative to clock noon by up to 16 minutes depending on the date. Around the winter solstice, the equation of time is causing solar noon to move progressively later each day. This shift affects both sunrise and sunset: both are moving later in clock time even as the solstice brings the absolute shortest period of daylight. Sunset reaches its earliest point first (around December 7-10), then the solstice arrives with the shortest day (December 21), and finally sunrise reaches its latest point (around January 3-7). All three are distinct events separated by about two weeks.

What are the three types of twilight and what are they used for?

Civil twilight is the period when the sun is 0 to 6 degrees below the horizon. It is bright enough for outdoor work without artificial lighting and is commonly used in legal definitions of daylight. Nautical twilight is when the sun is 6 to 12 degrees below the horizon. The horizon is still visible at sea and bright stars are visible, which historically allowed sailors to take celestial navigation sights with a sextant -- hence the name. Astronomical twilight is when the sun is 12 to 18 degrees below the horizon. The sky is dark enough for most telescopic observation, though the faintest deep-sky objects require the sun to be fully 18 degrees below the horizon, at which point true astronomical night begins. All three phases occur twice daily: in the morning (dawn) and evening (dusk).

How long does golden hour last and why does it vary?

Golden hour is the period when the sun is between 0 and 6 degrees above the horizon, immediately after sunrise and before sunset. It does not always last exactly 60 minutes. The duration depends on how steeply the sun rises or sets, which is determined by your latitude and the time of year. Near the equator, the sun rises almost vertically and golden hour may last only 20 to 30 minutes. At mid-latitudes in summer, when the sun rises at a shallow angle, it can last 60 to 90 minutes. At high latitudes near the solstice, the sun barely clears the horizon and golden hour can extend 2 to 3 hours. In winter at the same location, golden hour is shorter because the sun rises more steeply even though it does not rise as high. This calculator shows the exact duration for your location and date.

What is the equation of time and how does it affect sunrise and sunset times?

The equation of time is a seasonal correction that can shift solar noon by up to 16 minutes ahead of or behind clock noon. It is caused by two factors: Earth's slightly elliptical orbit (making the solar day slightly longer or shorter than 24 hours depending on the time of year) and Earth's axial tilt (causing the sun's east-west motion across the sky to be non-uniform). This correction affects the clock times of both sunrise and sunset. For example, in early November the equation of time makes solar noon about 16 minutes early relative to the clock, so both sunrise and sunset occur earlier than they otherwise would. In mid-February it makes solar noon about 14 minutes late, pushing both sunrise and sunset later. This is why a sundial and a clock agree only on approximately four dates per year.

Does the sun always rise in the east and set in the west?

Only approximately. At the equinoxes (around March 20 and September 22) the sun rises almost exactly due east and sets almost exactly due west everywhere on Earth. On other dates, the exact azimuth depends on your latitude and the date. In the Northern Hemisphere in summer, the sun rises north of east and sets north of west: at 51 degrees north latitude on the summer solstice, sunrise is around 49 degrees (NNE) and sunset is around 311 degrees (NW). In winter at the same location, sunrise is around 129 degrees (SE) and sunset around 231 degrees (SW). Near the poles, the sun can rise almost due north or south at certain times of year. At the equator, the azimuth variation is small, with sunrise always within about 23 degrees of due east.

How does latitude affect day length in summer and winter?

Day length varies dramatically with latitude. On the equator, day and night are always close to 12 hours each with only a few minutes of variation through the year. At 30 degrees north, the longest day is about 13.7 hours and the shortest is about 10.3 hours. At 45 degrees north, those values are about 15.5 hours and 8.8 hours. At 60 degrees north, the longest day is about 18.5 hours and the shortest about 5.5 hours. Above the Arctic Circle at roughly 66.5 degrees north, the sun does not set at all around the summer solstice (midnight sun) and does not rise at all around the winter solstice (polar night). The length of polar night and midnight sun increases toward the pole, reaching 6 months each at the geographic poles.

What are Islamic prayer times and how do they relate to sunrise and sunset?

Islamic prayer times are derived from the sun's position. Fajr prayer begins at dawn, typically defined as when the sun is approximately 15 to 18 degrees below the horizon (near astronomical dawn), depending on the calculation method used. Shurooq (when prayer is not permitted) coincides with actual sunrise. Dhuhr prayer begins just after solar noon, the moment the sun crosses the local meridian. Asr prayer time is calculated from the sun's altitude using a shadow-length rule rather than a fixed angle. Maghrib prayer begins immediately at sunset. Isha prayer begins when the evening red glow disappears, roughly corresponding to nautical or astronomical dusk (sun 12 to 18 degrees below horizon) depending on the jurisprudence. At high latitudes in summer where astronomical night does not occur, scholars have additional guidance on estimation methods.

What is atmospheric refraction and how much does it affect sunrise and sunset times?

Atmospheric refraction is the bending of light as it passes through Earth's atmosphere. The atmosphere is denser near the ground than at altitude, so light rays curve downward slightly. When you see the sun sitting on the horizon, it has geometrically already dropped about 0.567 degrees below it, but its image has been refracted (bent) back up to the horizon. Adding the sun's angular radius of about 0.267 degrees (since sunrise is defined as the moment the upper limb first appears), the standard correction used in all solar calculators is 0.833 degrees of depression at the moment of sunrise and sunset. This makes sunrise occur about 2 to 5 minutes earlier and sunset 2 to 5 minutes later than it would on an airless planet. Refraction is slightly stronger on cold, dense days and slightly weaker on hot, low-pressure days, which is why the exact times can vary by a minute or two from the predicted values on any specific day.

What is blue hour and when does it occur?

Blue hour is the period of civil twilight when the sun is between roughly 4 and 6 degrees below the horizon, occurring just before sunrise and just after sunset. During this time, the sky takes on a deep, saturated blue color because the sun is still illuminating the upper atmosphere with indirect light while the ground and horizon are in shadow. Street lights, building lights, and illuminated signs are still on or have just come on, creating a strong visual contrast between the warm artificial lighting and the cool blue sky. This contrast makes blue hour highly prized for architectural and urban landscape photography. Blue hour typically lasts 20 to 40 minutes depending on latitude and season, and like golden hour, it lasts longer at high latitudes where the sun moves at a shallow angle to the horizon.

Sunrise Sunset Calculator – Times, Twilight & Golden Hour

Location & Date

Quick location

Latitude (°N)

Longitude (°E)

UTC offset (timezone)

Sunrise

06:15

54.1° NE

Sunset

21:58

305.9° NW

Solar Noon

14:06

EoT: 5m 41s

Day Length

15h 43m

2 min shorter

Morning

Astronomical Dawn

Sun −18°

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Nautical Dawn

Sun −12°