Street View for the Sun
Heliora is a free web app for photographers and sky-watchers. There is no iOS or Android app. Drop a pin anywhere on Earth and see the sun, moon and Milky Way against the real terrain on the horizon from that spot.
The Problem
Published sunrise and sunset tables use a flat horizon, so they give the same time for a valley floor and the ridge above it. Some photography apps let you check terrain by hand, one obstacle at a time. Heliora computes the whole horizon.
On a valley floor the gap between the official time and the last direct sun can be hours, not minutes: at Lauterbrunnen on 21 December the sun leaves at 13:25, 3 h 18 min before the official sunset. The mountain light table gives computed times for six mountain towns, checked against the published sunless periods of Rjukan and Viganella.
Heliora reads satellite elevation data, ray-casts a 360° horizon profile from your exact coordinates, and uses that horizon for everything it shows: sun times, golden hour, sun, full-moon and planet line-ups behind a summit, Milky Way core times and eclipses. Where it can be wrong is on the method and accuracy page.
Key Features
Terrain-adjusted sun times
First and last direct sunlight computed against a 360° horizon profile from satellite elevation data, not the flat-horizon table. Worked example: when the sun really sets behind the mountains.
The sky from your pin
A sky dome drawn from the pin with the real terrain silhouette on the horizon, rendered in the browser. Drag to look around and move the time control to watch the sun or moon cross the skyline. Start here: sun path planner.
Full moon behind a summit
Pick a named summit and Heliora searches the next 18 months of full moons for the nights it rises or sets behind it, dropping the ones the terrain would hide. Computed dates for the Matterhorn, Half Dome, Mount Fuji, Mount Etna and Montserrat.
When the core clears the ridge
On new-moon nights in full darkness, the time the galactic centre stands above the computed skyline at your pin, how long it stays in view and its highest point. Computed table: Milky Way over the mountains.
Golden hour that clears the terrain
Golden light counts only while the sun is below 6° and above the ridge. "Find a better day" ranks the upcoming days by the longest continuous visible window at your pin, with start, end and compass bearing.
Sun and planets behind a landmark
The same summit search for the sun over the next 12 months and for a naked-eye planet over the next 60 nights. Candidates in daylight or behind the horizon are dropped. How to scout a spot you have not visited: remote scouting.
Any pin, one link
Terrain covers every landmass. Every view has a URL that restores the pin, date, time and camera, so a plan can be sent to the person who will be standing there. Which apps do this and which do not: moon photography apps compared.
What Makes Heliora Different
Side by side with a flat-horizon sun calculator:
For a fuller product-by-product account, including what the paid apps offer that Heliora does not, see the comparison page.
How It Works
Solar eclipses
Heliora launched around the total eclipse of 12 August 2026 over northern Spain, when about 27,000 people used it on the day. The 3D sky renders any eclipse from the pin, with contact times, obscuration, sky darkening, corona and whether a ridge takes the low sun mid-event.
Next: 2 August 2027 across southern Spain, North Africa and Egypt. 2026 vs 2027 compared › · Replay 2026 from Oviedo ›
Coverage
9 August 2026. Il Post wrote about Heliora: Come osservare l’eclissi solare del 12 agosto dall’Italia
11 August 2026. Internazionale wrote about Heliora: Come vedere l’eclissi solare del 12 agosto
12 August 2026. Il Post wrote about Heliora: Come vedere l’eclissi solare di stasera
12 August 2026. t-online covered Heliora: Sonnenfinsternis heute: Tool zeigt Ihnen Blickrichtung und Bedeckung
Heliora was also linked from CERN's eclipse-safety announcement for its Geneva site, Eyes on the sky: a rare solar eclipse will be visible from CERN on 12 August (10 August 2026), as a way to find a viewing spot. That page is a safety notice from CERN's HSE department, not a review or an endorsement of Heliora.
Frequently Asked Questions
- What is Heliora?
- Heliora is a free, browser-based tool that shows the sun's exact path from any location on Earth, with sunrise and sunset times adjusted for real terrain. It uses satellite elevation data to compute when mountains, ridges, or hills actually block the sun at your specific position, not just the flat-horizon time that published tables show.
- Is Heliora free?
- Yes. Heliora is completely free to use. No account, no sign-up, no paywall. Open the app, drop a pin, and get terrain-adjusted sun data immediately.
- Who makes Heliora, and how is it paid for?
- Heliora is built and run by Simon Carroll, an independent developer in Spain. It has no ads and no paid tier. He pays the hosting; the map, terrain, weather and search data come from free public providers and the calculations run in your browser, which keeps that cost small.
- How accurate are the sun times?
- Sun and moon positions are computed to within ±1 arcminute using the astronomy-engine library. Terrain data comes from the free AWS Terrain Tiles dataset (Terrarium tiles, built from NASA SRTM, USGS 3DEP and other sources), with elevation sampled at roughly 110 m spacing (from source datasets of ~30 m resolution). Terrain-adjusted sunrise and sunset are usually within a few minutes; the error comes from the elevation data, not the astronomy. When we re-ran our moon pages on ~30 m elevation data, rise times moved by 0 to 2 minutes at four of five sites and 3 to 4 minutes at Half Dome. Those are comparisons between elevation datasets, not field measurements, and the error is largest where a steep, narrow ridge is close to you. Full details are on the method & accuracy page.
- How does it handle eclipses?
- Heliora computes local eclipse circumstances for any location using a precision astronomical engine. It calculates contact times (C1 through C4), obscuration percentage, and eclipse type from your exact coordinates. The 3D sky view renders the eclipse in real time, with sky darkening, corona and diamond ring effect, and shows whether nearby terrain blocks the low sun during the event.
- What makes it different from TimeAndDate or PhotoPills?
- Published sunrise and sunset tables assume a flat horizon. They give the same time whether you're in a valley or on a ridge. Heliora decodes real elevation data from satellite terrain tiles, ray-casts a 360° horizon profile from your exact coordinates, and uses it automatically for rise and set times, Milky Way core times and its landmark line-up scans. It also renders a full 3D sky dome with the actual terrain silhouette. PhotoPills and TPE can check terrain too, and do things Heliora does not; the comparison page lists them.
- Is Heliora the same as the iOS apps named Heliora?
- No. Heliora is the free web app at heliora.app, built in Spain, and it has no native iOS app. Two App Store apps from other developers use the name, "Heliora: Sun Path Tracker" and "Sun Position Heliora". Neither is affiliated with heliora.app. The terrain-horizon features, eclipse simulation and landmark line-up scans described on this page belong to heliora.app.
- Does it work on mobile?
- Yes. Heliora works in any modern mobile browser (Chrome, Safari, Firefox) with no install. The interface adapts with a bottom sheet panel and touch-friendly controls.
Free. No account needed. Drop a pin and see the sun, moon and Milky Way against your real horizon.