See tonight's moon — even through the rain

What this page computes, and how

Everything on this page is calculated live in your browser from the actual orbital geometry of the Earth and Moon — not read from a lookup table and not fetched from a server. The Sun’s position comes from the standard solar-position equations used by national observatories; the Moon’s phase, illumination, and rise and set times come from the same low-precision lunar theory that underlies most almanac software; and the exact new and full moon instants come from Meeus’s phase algorithm. The practical result is that every number is right for the date and place you choose, and the page never goes stale — the model, not the answers, is what is fixed.

How a moon phase is defined

A phase is an angle, not a shape. The Moon is a sphere lit from one side by the Sun; what changes night to night is where the Sun, the Earth and the Moon stand relative to each other. The illuminated fraction — the share of the disc facing us that is lit — runs from 0 at new moon to 1 at full moon. The phase angle is that same cycle written as a fraction from 0 to 1, and the familiar names are bands inside it: new, waxing crescent, first quarter, waxing gibbous, full, waning gibbous, last quarter, waning crescent. One full cycle is the synodic month, which averages 29.530588 days. Because the Moon’s orbit is elliptical, individual cycles vary by several hours, which is why the exact times are computed rather than counted off a fixed calendar.

How sunrise, sunset and golden hour are defined

Sunrise and sunset are not the moments the Sun’s centre crosses the horizon. They are set by the top edge of the solar disc, and the atmosphere lifts that edge by about half a degree, so the working definition is the moment the Sun’s centre reaches 0.833° below the horizon. Golden hour is not a fixed sixty minutes either: it is a band of solar altitude running from 6° above the horizon down to 4° below it, and it happens twice a day, after sunrise and before sunset. The blue hour is the next band down, from 4° to 6° below the horizon. The calculators report all of these as local clock times for the city you pick.

Moonrise, moonset and the phase

The Moon keeps different hours from the Sun, and the reason is the phase itself. Against the fixed stars the Moon slides eastward by about 13.2° a day — one full turn of 360° divided by the 27.32-day sidereal month — so the Earth has to rotate a little further each night before the Moon is back in the same spot. That daily head start becomes roughly 50 minutes of extra delay on average, though the exact figure swings from about 20 minutes to about 80 minutes with the season and your latitude, which is why the times here are computed rather than counted off a calendar.

That table is the whole link between illumination and the clock. A new Moon rises and sets with the Sun because it sits beside it in the sky; a full Moon rises as the Sun sets and sets as the Sun rises because it sits opposite; the quarters fall halfway between, coming up around the middle of the day or the middle of the night. What the table cannot give you is the exact minute, because the clock times still move with the date, the latitude and the time of year.

Worked example — a full Moon over New York. On 26 October 2026 the Moon is 100% illuminated. Over New York it rises at 16:52 and sets at 06:54 — nine minutes before that day’s sunset of 17:01, and just over half an hour after sunrise at 06:20, so the full Moon is up for the entire night. Contrast 5 October 2026, when the Moon was a 26%-lit waning crescent: it rose at 00:07 and had set by 15:10, hours before dark. The crescent is a morning object; the full Moon is an all-night one.

Three worked examples

Example 1 — New York, 5 October 2026. For the city at 40.71°N, 74.01°W, the Sun rises at 05:57 and sets at 17:33, a day of 11.60 hours, with solar noon — the Sun’s highest point — at 11:45. The evening golden hour opens at 16:56 and closes at 17:49: 53 minutes of low, warm light, followed by a blue hour from 17:49 to 17:59.

Example 2 — Singapore, the same date. Move to 1.35°N, 103.82°E and the day is close to an even split: sunrise 06:51, sunset 18:57, a day of 12.10 hours. The evening golden hour runs from 18:29 to 19:09 — 40 minutes, shorter than New York’s 53, because near the equator the Sun drops toward the horizon almost vertically and crosses the 6°-to-(−4°) band quickly. Latitude, not luck, sets the length.

Example 3 — the Moon, the same date. On 5 October 2026 the Moon is a waning crescent about 26% illuminated over New York, rising at 00:07 and setting at 15:10. The next new moon is exact at 15:50 UTC on 10 October 2026, and the next full moon at 04:12 UTC on 26 October 2026. A phase is a global instant, but the illumination you read at local noon shifts by a few percent between cities, because noon arrives at a different moment in each place — over New York, London and Singapore on this same date the figure moves from about 26% to 32%.

All times are local clock times for 5 October 2026, computed from the Sun’s real position on that date. Day length is sunset minus sunrise; the golden-hour windows run from the Sun crossing +6° down to −4°.

Why latitude and season change the answer

Two things move every sunrise and every phase: the Earth’s 23.4° tilt, which slides the Sun’s declination north and south through the year, and your latitude, which fixes the angle at which the sky’s daily circles meet your horizon. Near the equator the Sun rises and sets almost vertically all year, so days stay close to twelve hours and golden hour stays short. Toward the poles the same geometry stretches the day dramatically: London’s 11.40-hour day on 5 October 2026 becomes 16.63 hours by the June solstice and shrinks to 7.82 hours at the December solstice, while Singapore barely moves. The Moon adds its own rhythm on top — rising roughly 50 minutes later each day and glowing more brightly as it approaches full, which is why a bright Moon can light a night landscape the sunset window has just left behind.

Private and instant

All of this happens on your own device. No location is uploaded, there is no account and no tracking script; you pick a date and a city and the answer appears in milliseconds, and it keeps working offline once the page has loaded. That design is also why the numbers are trustworthy: there is no server-side table that can go out of date, only equations evaluated at the moment you ask.

Sources and standards