Q: How do I use the moonrise bearing for compositional planning?

The moonrise bearing is displayed in both degrees (0–360°) and a compass direction abbreviation such as ESE or NNW. Zero degrees is true north; 90° is due east; 180° is due south; 270° is due west. To use it for compositional alignment: note the bearing for your chosen date and location, then open a mapping tool and draw a line from your planned shooting position at that bearing angle. The moon will rise along that line — you can identify which landmark, ridgeline, or structure it will appear above or behind. Moonset bearing works identically in reverse — it tells you where on the western horizon the moon will disappear, useful for planning silhouette compositions at dawn with a setting full moon. The bearing shown is the moon's azimuth at the moment of rise or set — when it is exactly on the horizon. As it climbs, its azimuth shifts. For precise alignment at a specific altitude, the peak altitude and time fields give you the arc's midpoint.

Question 1

What exactly is an ephemeris, and why does it matter for photography?

Accepted Answer

An ephemeris is a table of predicted positions for celestial objects at specific times and locations. The word comes from the Greek for daily — historically, astronomers and navigators used printed ephemerides to know exactly where the sun, moon, and planets would appear in the sky on any given date. For photographers, this matters because light quality is entirely determined by geometry — the angle of the sun below the horizon, the height of the moon above it, and the fraction of the moon's disc currently lit. Knowing these values in advance means you can arrive at a location at exactly the right moment, facing exactly the right direction, without guessing.

Question 2

What is the difference between blue hour and golden hour?

Accepted Answer

They refer to different positions of the sun relative to the horizon, which produce entirely different kinds of light.

Golden hour occurs when the sun is within roughly 6° of the horizon — from civil dawn through sunrise in the morning, and from sunset through civil dusk in the evening. The atmosphere scatters blue wavelengths and passes warm reds and oranges, creating directional, low-angle light with long shadows and rich colour.

Blue hour occurs when the sun is between 6° and 12° below the horizon (nautical twilight). The sky holds a deep, even blue with no direct sunlight at all. This is the sweet spot for urban and architectural photography — artificial lights come on while the sky still retains colour and detail, producing a near-even exposure balance. The tool labels these precisely: Blue Hour (AM) marks nautical dawn, Golden Hour (AM) marks civil dawn, and the mirror events are shown separately for the evening.

Question 3

How is the A–F sky grade calculated?

Accepted Answer

The grade is a weighted composite of three sub-scores, each shown as its own dial bar in the interface. Darkness (45%) — multiplies illumination percentage by the moon's altitude factor at 10 pm to estimate effective glare in your sky. A full moon on the horizon produces far less glare than a half moon directly overhead. Moon altitude (30%) — the moon's angular elevation at 10 pm local time. A moon below the horizon scores 100 regardless of phase; every degree above the horizon reduces the score. Phase (25%) — illumination percentage simply inverted. New moon = 100, full moon = 0. The simplest factor; it ignores position entirely. Note: the altitude sub-score is always sampled at 10 pm local time. If you plan to shoot at 2 am or 4 am, check the moonrise, moonset, and peak altitude times directly — the moon's position may be very different from what the grade implies.

Question 4

Does a high grade guarantee good astrophotography conditions?

Accepted Answer

No — the grade is a lunar interference score only. It tells you how much the moon will compromise your dark sky. It says nothing about cloud cover — an A-grade night under thick overcast is completely unusable. It also says nothing about light pollution — the grade assumes a dark sky, so an A-grade location inside or near a major city will still suffer severe artificial light pollution. Use the grade alongside a Bortle scale map for your specific site. Atmospheric seeing — turbulence in the upper atmosphere — also affects the sharpness of stars and planetary detail regardless of moon phase. Think of the grade as one dimension of a multi-factor decision. A night rated B or C at a genuinely dark-sky site often outperforms an A-grade night in the suburbs.

Question 5

How far ahead can I plan using the calendar?

Accepted Answer

The tool is not limited to any specific date range. SunCalc, the astronomical library it runs on, can compute accurate sun and moon positions for any date — past or future. You can navigate the calendar months or years ahead, or type any date directly into the date picker. The monthly calendar view shows an A–F grade badge and moon phase icon for every day of the month. Use the arrows to move forward month by month to find clusters of A and B grades that align with your travel plans or local seasons. The lunar cycle repeats every 29.53 days, so the same phase recurs roughly once per month. Scouting three to six months ahead is realistic for most photography trips.

Question 6

How accurate is the location search?

Accepted Answer

City searches use the OpenStreetMap Nominatim geocoder, which returns the latitude and longitude of the named place. The tool then computes all sun and moon data for that exact coordinate pair. For most planning purposes — finding the golden hour time for a city, or checking the moon grade for a region — city-level accuracy is more than sufficient. For precise compositional alignment, click directly on the map to pin the exact vantage point. The map accepts clicks anywhere on Earth at full coordinate precision. Your last-used location is saved automatically in your browser between sessions, so returning users do not need to re-enter their location each time.

Question 7

Why do moonrise and moonset times shift so much day to day?

Accepted Answer

Unlike the sun, which rises and sets within a fairly consistent window each day, the moon shifts its rise and set times by roughly 50 minutes later each day. This is because the moon orbits Earth in the same direction Earth rotates — the planet has to turn an extra ~13° each day to catch up to the moon's new position, which takes about 50 additional minutes.

Over a full 29.53-day lunar cycle, the moon effectively completes one full trip around the clock — rising at dusk one week, rising at midnight the next, rising at dawn the week after. This is why a given moon phase occupies a completely different part of the night sky depending on the time of year and your latitude. For astrophotography, what matters most is not just when the moon rises but whether it sets before astronomical dark begins. An A-grade date where the moon sets at 11 pm is very different from one where it never rises at all.

Question 8

What timezone are the displayed times in?

Accepted Answer

All times displayed use your browser's local timezone — not the timezone of the location you have searched. If you search for a city in a different timezone from your own, sunrise, moonrise, and all light event times will appear in your local time. For most pre-trip planning this is workable, but be aware of the distinction when planning for distant destinations. Example: if you are in London (UTC+0) and search for Tokyo (UTC+9), a Tokyo sunrise shown as 21:00 in the tool means 9 pm London time — which is 6 am Tokyo time. The underlying data is correct; only the display timezone shifts.

Question 9

Is a D or F grade night ever worth shooting?

Accepted Answer

Absolutely. D and F grade nights are not wasted nights — they simply require a different creative approach. A high full moon at or near peak altitude floods a landscape with soft, directionless light that no artificial setup can replicate at scale. Long exposures of moonlit seascapes, snow-covered mountains, or open deserts can be extraordinary on F-grade nights. The moon acts as a powerful ambient key light. Environmental portraits under a full moon, moonlit fog in a forest, or the moon itself as the primary subject with a foreground silhouette are all techniques that specifically require the conditions a low grade describes. Use the peak altitude and peak time fields to know when the moon will be at maximum brightness and elevation — this is your equivalent of golden hour for moonlit work.

Question 10

How do I use the moonrise bearing for compositional planning?

Accepted Answer

The moonrise bearing is displayed in both degrees (0–360°) and a compass direction abbreviation such as ESE or NNW. Zero degrees is true north; 90° is due east; 180° is due south; 270° is due west.

To use it for compositional alignment: note the bearing for your chosen date and location, then open a mapping tool and draw a line from your planned shooting position at that bearing angle. The moon will rise along that line — you can identify which landmark, ridgeline, or structure it will appear above or behind.

Moonset bearing works identically in reverse — it tells you where on the western horizon the moon will disappear, useful for planning silhouette compositions at dawn with a setting full moon. The bearing shown is the moon's azimuth at the moment of rise or set — when it is exactly on the horizon. As it climbs, its azimuth shifts. For precise alignment at a specific altitude, the peak altitude and time fields give you the arc's midpoint.

Phase	What it means for photography
Deep night	Sun more than 18° below the horizon. True astronomical darkness — the best window for Milky Way, star trails, and deep sky imaging. No solar contamination of any kind.
Astro. twilight	Sun 12–18° below the horizon. Sky brightens subtly but faint nebulae and the Milky Way core remain visible. The outer edge of astrophotography viability.
Blue hour	Sun 6–12° below the horizon (nautical twilight). The sky holds a deep, even blue — ideal for urban scenes and architecture where you want ambient sky balanced with artificial lighting.
Golden hour	Sun within roughly 6° of the horizon (civil twilight through sunrise/sunset). Warm, directional, low-angle light with long shadows. Quality peaks at the precise moment of sunrise and sunset.
Daylight	Sun above the golden hour threshold. Neutral overhead light. The tool does not sub-divide this period — use it to scout, travel, or wait for the PM golden window.

A	Pristine dark sky Composite 80–100	Moon is new, absent, or well below the horizon at your shooting time. Maximum contrast for Milky Way core, nebulae, and faint deep-sky objects. These nights are rare — plan around them.
B	Excellent conditions Composite 62–79	Thin crescent present or moon rising late in the night. Wide-field Milky Way photography and foreground-lit compositions work well. Minor compromise on the faintest targets only.
C	Fair — some interference Composite 44–61	Quarter moon present and visible for part of the night. Deep sky imaging of faint nebulae suffers noticeably. Landscape night photography using the moon as a deliberate light source can still produce strong results.
D	Poor — bright moon Composite 26–43	Gibbous moon high in the sky through much of the night. Stars wash out significantly; the Milky Way is barely visible or not at all. Moonlit landscape work, long exposures of reflective water, or portraits under natural moonlight become viable creative options.
F	Moon washout Composite below 26	Near-full or full moon at significant altitude. Dark sky photography is not viable. Redirect to moonscape work, moonlit seascapes with long exposures, or simply use the moon as a powerful key light for environmental portraits.

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