Sun and Moon FAQ
Questions and answers about the sunrise, sunset and moon calculator. Everything it does happens in your browser.
Last Updated: November 3, 2026
1. General Questions
Q1: What is Sun and Moon?
A1: A calculator for the sky above any place on Earth, on any date from 1800 to 2199. It gives sunrise, sunset, solar noon, day length, twilight, golden hour and blue hour; the path and height of the Sun and Moon; moon phase, moonrise, moonset and distance; eclipses as seen from your place, meteor showers, equinoxes, solstices and supermoons; a Hindu panchang for sunrise with Rahu kaal and the muhurtas; and the Islamic (Hijri) date.
Q2: How much does it cost?
A2: Nothing. It is free, with no registration and no limit. Like every page on ZeroDataUpload, it is supported by advertising.
Q3: Who is it for?
A3: Photographers planning around golden hour, people who fast or pray by sunrise and sunset, anyone following the panchang or the Islamic calendar, sky watchers looking for eclipses and meteor showers, gardeners and walkers who want to know the day length, and the curious who want to see the Moon on the night they were born.
Q4: Do I need to install anything or create an account?
A4: No. Open the page in any modern browser (Chrome, Edge, Firefox, Safari or Opera) on a computer, tablet or phone. Your place and settings are kept in that browser, so there is nothing to sign in to.
Q5: Is my location sent anywhere?
A5: No. Every time and date is worked out by this browser, and the places and dates you choose are not sent to a server. The page itself loads the site's ads and analytics, as every page on the site does; the Privacy Policy explains those, and your place is never part of them: the page title never names it, and the page does not put it into its own address.
Q6: Does it work without an internet connection?
A6: Once the page has loaded, yes: every calculation runs in the browser, so changing the place, the date or the view needs no connection.
2. Places and Time Zones
Q7: How do I choose my place?
A7: Click the place at the top left. Pick one of about 200 cities from the list, which starts with the ones nearest your current place, or type a name to search. Under Enter coordinates and time zone you can type any latitude and longitude, give the place a name and choose its time zone.
Q8: Why is there no Use my location button?
A8: This site does not ask browsers for your location on any page. Type your city, or copy the coordinates from a map app (press and hold the spot) into Enter coordinates and time zone.
Q9: How do I enter coordinates?
A9: Latitude is north (plus) or south (minus) of the equator, from -90 to 90; longitude is east (plus) or west (minus) of Greenwich, from -180 to 180. Decimal degrees work best, for example 19.2068 and 73.1836. You can also type both into the search box, separated by a comma.
Q10: Which time zone is used?
A10: The time zone of the chosen place, with its daylight saving time, from your browser's time zone data. For coordinates you type in, the time zone of the nearest listed city is suggested and you can choose any other.
Q11: Does it handle daylight saving time?
A11: Yes. Every time is in the local time of the place on that day. On the day the clocks change, the day is an hour shorter or longer, and the year in daylight shows the change as a step. Days on which the clocks change at midnight, as in Cuba or Chile, start at the right moment.
3. The Sun
Q12: What exactly is sunrise and sunset?
A12: The moment the top edge of the Sun meets a flat horizon at sea level, allowing for the usual bending of light by the air. This is the definition almanacs and weather services use.
Q13: How accurate are the times?
A13: They were checked against a professional ephemeris from NASA's Jet Propulsion Laboratory for 45 places from the equator to the Arctic, from 1901 to 2049: sunrise and sunset agree within a few seconds, twilight within half a minute, moonrise and moonset within a minute. Real views differ by more than that: hills, buildings, the height you stand at and unusual air near the horizon can move what you see by a few minutes.
Q14: What are civil, nautical and astronomical twilight?
A14: The light before sunrise and after sunset, in three steps. Civil twilight lasts until the Sun is 6 degrees below the horizon (first and last light), nautical twilight until 12 degrees, when the horizon at sea fades, and astronomical twilight until 18 degrees, after which the sky is fully dark.
Q15: What are golden hour and blue hour?
A15: Golden hour is while the Sun is between 6 degrees above and 4 degrees below the horizon, when light is warm and soft. Blue hour is while it is 4 to 6 degrees below, when the sky is deep blue. In the morning blue hour comes first; in the evening golden hour does.
Q16: Why is the day length a few minutes more than 12 hours at the equinox?
A16: Sunrise and sunset count the top edge of the Sun, not its centre, and the air lifts the Sun's image near the horizon, so on the day of an equinox day is a few minutes longer than night everywhere.
Q17: How is the shadow length worked out?
A17: From the Sun's height at the chosen moment: the shadow is the object's height divided by the tangent of that angle. Enter the height in metres, centimetres, feet or inches; the Sun view also says at what times the shadow is as long as the object.
Q18: What does the year in daylight show?
A18: Every day of the selected year as a column, from midnight at the top to midnight at the bottom, coloured by how high the Sun is. Under it are the longest and shortest days, the earliest and latest sunrise and sunset, and the dates of the equinoxes and solstices.
Q19: What happens near the poles?
A19: When the Sun does not set or does not rise, the page says so: Up all day or No sunrise, with the twilight that still happens. The same holds for the Moon.
4. The Moon
Q20: How is the Moon picture drawn?
A20: With the lit part as it is at that moment. As seen from here turns it the way it looks from your place, with straight up at the top, so a crescent tilts as it does in your sky; North up shows it as most photographs do.
Q21: What is the Moon's age?
A21: The days since the last new moon. A lunar month averages 29.53 days, so the full moon comes at an age of about 14.8 days.
Q22: What is a supermoon, a micromoon and a blue moon?
A22: A supermoon is a full moon closer than 360,000 km; it looks about 7 percent wider and 15 percent brighter than average. A micromoon is a full moon farther than 405,000 km. A blue moon is the second full moon in one calendar month.
Q23: Where do the full moon names come from?
A23: They are the traditional names used in North America and Europe, such as Wolf Moon in January and Cold Moon in December. The full moon nearest the September equinox is the Harvest Moon, the next one the Hunter's Moon. Each full moon also shows its Hindu name, such as Kartika Purnima, and the festival usually kept on it.
Q24: Why do moonrise times jump around?
A24: The Moon rises about 50 minutes later each day on average, but the gap changes a lot with the season and the Moon's path. Some days have no moonrise or no moonset at all, because one of them falls just after midnight.
5. Panchang and the Hijri Date
Q25: How is the panchang worked out?
A25: For sunrise at your place, with the Lahiri ayanamsa as the Indian Astronomical Ephemeris defines it. The tithi, nakshatra, yoga and karana are the ones in force at sunrise, each with the moment it ends and the one that follows. The ends were checked against the ephemeris and agree within half a minute; printed panchangs usually agree within a minute or two, because each uses its own method.
Q26: What are amanta and purnimanta months?
A26: Two ways of naming the lunar month. Amanta months end at the new moon and are used in Maharashtra, Gujarat and the south; purnimanta months end at the full moon and are used in most of north India. The dark half of the month (Krishna paksha) carries a different name in the two systems. Choose under Settings.
Q27: What is an adhika month?
A27: An extra lunar month in which the Sun enters no new sign. It comes about every 32 months and keeps the lunar calendar in step with the seasons; in 2026 it is Adhika Jyeshtha. The tool names it as panchangs do.
Q28: How are Rahu kaal, Yamaganda and Gulika kaal found?
A28: The daytime from sunrise to sunset is divided into eight equal parts, and each weekday has its own part for each period, as in the standard tables. Because sunrise and sunset change, the times change with the place and the season.
Q29: Which Islamic calendar is used?
A29: The Umm al-Qura calendar of Saudi Arabia, from its published tables for 1924 to 2077 (each day was checked against them); for years outside them the browser's own calculation is used, and the page says so. The Islamic day begins at sunset, so the page also shows the date after sunset. Where months begin with a local sighting of the new crescent, dates can be a day later; follow your community's announcement for fasts and festivals.
6. Eclipses and Sky Events
Q30: Which eclipses are listed?
A30: Every solar and lunar eclipse of the next six years from the selected day, up to ten. For each one the page says whether it can be seen from your place, and gives the local times: when it starts, when it is greatest and when it ends, with the Sun or Moon's height.
Q31: How much of the Sun will be covered?
A31: For a solar eclipse seen from your place, the page gives the share of the Sun's disc covered at the greatest moment, or says when it is total or a ring of fire. These were checked for 27 eclipses at different places and agree within a fraction of a percent and a minute. Never look at the Sun without certified eclipse glasses, even when most of it is covered.
Q32: What do Dark sky, Some moonlight and Bright Moon mean for a meteor shower?
A32: How much moonlight there is at 3 am on the night of the peak at your place: Dark sky when the Moon is less than 30 percent lit or has set, Bright Moon when it is more than 65 percent lit and up. The page also says how high the shower's radiant climbs at your latitude.
Q33: Can I add an event to my calendar?
A33: Yes. Eclipses you can see and meteor shower nights carry a calendar button that saves a calendar file (.ics) with the times and the place's name. Open it to add the event to Google Calendar, Outlook or Apple Calendar.
7. Your Data and Settings
Q34: What does the tool remember?
A34: Your place, up to six recent places and your settings (clock, distances, month names, the Moon picture and the shadow's height and unit), in this browser's storage on this device, so the page opens where you left it. Nothing is kept on a server.
Q35: How do I make it forget?
A35: Open Settings and choose Forget saved place and settings. Everything Sun and Moon keeps in this browser is removed, and the rest of the site is not touched.
Q36: What does a shared link carry?
A36: The link button copies an address that opens the same place, date and view: it carries the place's coordinates, its name and its time zone. Share it only where you mean to. When the link is opened, the page reads it and takes it off its own address straight away.
Still have a question?
The help page walks through every part of the tool. For anything else, use the contact form and say which place and date you looked at.