Sunrise and sunset times for your location
Sunrise and sunset are among the most useful daily astronomy events because they define the changing boundary between daylight, twilight and night. The calculator above uses the latitude, longitude and date you choose to estimate sunrise, sunset, solar noon and the length of daylight for that observing location. It also separates civil, nautical and astronomical twilight, which is important for photographers, satellite watchers and anyone planning an evening under the stars. Sunrise is not identical everywhere in a time zone: two cities that share the same clock can still see the Sun rise many minutes apart because longitude, latitude, season and local geometry are different.
For skywatchers, the most important value is often astronomical twilight rather than sunset itself. Civil twilight begins or ends when the center of the Sun is about 6 degrees below the horizon. Nautical twilight uses about 12 degrees, and astronomical twilight uses about 18 degrees. Once evening astronomical twilight ends, the sky is normally dark enough for many faint stars and deep-sky targets, assuming clouds, Moonlight and artificial light pollution are not limiting the view. That is why this page links directly to Best Time to Stargaze Tonight and Night Sky Tonight: sunset tells you when daylight ends, while those tools help you decide what is actually worth observing afterward.
Golden hour, blue hour and useful observing windows
The period around sunrise and sunset is also valuable for photography. Golden hour generally describes the low-Sun period when warm directional light becomes prominent, while blue hour refers to the cooler twilight period when the Sun is below the horizon but the sky still holds substantial color. Exact photographic definitions vary, so the tool treats these as practical planning windows rather than rigid physical boundaries. For satellite observing, a different combination matters: the observer should be in darkness while the spacecraft remains sunlit at altitude. That is why an ISS pass shortly after sunset or before sunrise can be much brighter than a pass in the middle of the day. You can continue from this page to ISS Visible Tonight or the ISS Live Tracker.
Day length changes through the year because Earth’s rotational axis is tilted relative to its orbit around the Sun. Around an equinox, day and night are comparatively balanced across much of Earth. Around a solstice, the difference becomes much larger, especially at high latitudes. Near the Arctic and Antarctic circles, there can be dates when the Sun does not set or does not rise at all. A robust sunrise calculator must therefore handle more than a simple fixed time offset. The result also depends on the chosen date and coordinates, and the displayed local clock time depends on the browser’s time zone. If you are planning observations while travelling, make sure the device time zone matches the location you are using.
Why published sunrise times can differ slightly
Sunrise and sunset are usually defined using the upper edge of the apparent solar disk and a standard allowance for atmospheric refraction near the horizon. Real atmospheric pressure, temperature, elevation and the shape of your local horizon can shift the moment you first see sunlight. Mountains, tall buildings and trees can delay a visible sunrise or produce an earlier apparent sunset even though the astronomical calculation is correct for a flat geometric horizon. For that reason, use these times as high-quality planning estimates rather than a claim that the first direct ray of Sun must appear at an exact second from every viewpoint.
The U.S. Naval Observatory Astronomical Applications data services are a useful authoritative reference for rise, set, transit and twilight concepts. SpaceTracker.live keeps the practical observing workflow on one site: set your location here, note the end of twilight, then check the Moon, planets, constellations, meteor activity or satellite passes using the related tools. For Moon-specific local timing, use Moonrise & Moonset. If the Moon is bright during your planned dark-sky window, Moon Phase Tonight shows how much of the lunar disk will be illuminated.
How to use this page for tonight’s observing plan
Start by selecting your observing location and today’s date. Note sunset, then compare the end of astronomical twilight with the time you actually plan to go outside. If you want bright planets, you may not need complete darkness, so check Planets Visible Tonight around civil or nautical twilight. If you want the Milky Way or faint constellations, the darker period after astronomical twilight is more useful; open Milky Way Visible Tonight and Constellations Visible Tonight. If meteors are your priority, continue to Meteor Shower Tonight. This creates one connected observing plan from daylight through twilight into the night sky rather than treating sunrise and sunset as isolated clock times.