Solunapath is an interactive 'flipped stereographic' projection diagram showing the paths of the Sun and Moon across
the sky for the selected location, date and time. The moving marker shows the position of the object for the current
or selected time, a label with the azimuth (φ) and altitude (θ), and in the case of the Moon the percent illuminated
(%). The Moon marker also shows the current phase. The blue summary bar shows the chart's latitude, longitude, date,
time, mode (live or static), and any activity messages.
How to read the chart
- Outer circle = horizon (0° altitude). Inside the circle is above the horizon; outside is below.
- Concentric circles = altitude (10° steps). Higher circles mean the object is higher in the sky.
- Radiating lines = azimuth (direction). N / E / S / W are shown around the edge.
- Red curve = Sun path. Grey dashed curve = Moon path.
- Hour ticks mark the position at each hour along the path.
Twilight rings
Dashed rings show common twilight definitions below the horizon:
civil (−6°), nautical (−12°), and astronomical (−18°).
If the Sun stays above a ring all day, that twilight period does not occur.
Controls
- Location: Station (Lerwick), your current location (if allowed), or manual latitude/longitude.
- Date: Choose any date to inspect the sky.
- Time: Choose a time or check Live to follow real time.
- UTC: Choose local time (unchecked) or UTC (=GMT, checked).
- Now: Sets date/time to the current moment and enables Live.
- Show Sun / Moon and Sun / Moon Ticks: Toggle each path and its hour markers.
Tip: when entering manual coordinates, latitude is −90…+90 and longitude is −180…+180 (max 3 decimals).
Solar, Sidereal and rise/set times
- Solar time is “sundial time” for the selected location and time (includes the equation of time).
- Sidereal time is based on the Earth's rotation relative to the fixed stars rather than the Sun.
- Rise and set times for the Sun and Moon (note that times may vary slightly from published figures).
Tip: selecting UTC sets sidereal time to GMST (Greenwich Mean Sidereal Time).
Extras menu [⋯] and export tools
- Select theme: Choose auto (device theme), light or dark (overrides device).
- Help: Opens this dialog.
- Full screen: Hides browser UI for a cleaner view (availability varies by device/browser).
- Copy link: Copies the current settings to the clipboard as a shareable link (URL).
- Restore defaults: Resets all controls to default values.
- Export SVG/PNG (below diagram): Exports an image of the chart with the current settings.
Tip: SVG is a Scaleable Vector Graphic XML file with embedded styling, PNG is an 800px x 800px raster image.