Support for Solar

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Location

Solar asks for the location on first launch. An approximate location is enough: iOS then shifts it by a few kilometres, which changes the times of an eclipse by only a few seconds.

If permission was declined, it can be granted again in the iPhone settings under “Privacy & Security”, “Location Services”, “Solar”. It also works without: under “Places”, any place can be added by hand with “Search for a city or place”. Your own location is refreshed every time Solar comes back to the foreground.

Reminders

Turn on “Reminders” in the app’s settings and choose when: one week before, one day before, on the morning of the event (8 am local time at the observing place) or five hours before. Reminders apply to the selected place.

Alerts at the start, maximum and end are available for eclipses marked with “Follow live”. iOS allows an app at most 64 scheduled notifications; anything beyond that is scheduled by Solar the next time it is opened.

If no alerts arrive, check in the iPhone settings under “Notifications”, “Solar” that they are allowed. With “Add to Calendar”, an eclipse also goes into the calendar as an event.

Weather

For dates within the next ten days, Solar shows a real cloud cover forecast from Apple Weather for the hour of maximum. There is no forecast for later dates. Solar then shows how cloudy it was in this region in the same month at the same time of day from 2002 to 2021. That is a probability, not a forecast.

Without a network, Solar shows the last loaded value and marks it as such. Everything else, including the whole eclipse calculation, works without internet.

Apple Watch

The watch determines its own location. Location permission has to be granted on the watch, the first time the app is opened there. For the watch face there are the complications “Next Eclipse”, “In the Sky” and “Sky Brightness”. Sky Brightness needs the network once for a new place.

Apple Vision Pro

The Vision Pro takes the selected place and the saved places from the iPhone, via iCloud. Both devices must be signed in with the same Apple Account, with iCloud turned on. Changing the place is therefore done on the iPhone. Until the first sync, the Vision Pro computes for Cologne; after a change, the sync can take a moment.

Storage

Solar keeps weather data, map tiles and satellite orbits on the device so they are available offline. In the app’s settings, “Clear cache” deletes them.

Where the data comes from

• Eclipses: Besselian elements from NASA’s Five Millennium Canons by Fred Espenak and Jean Meeus (NASA/TP-2008-214170 and NASA/TP-2009-214173), eclipse.gsfc.nasa.gov.
• Methods: Jean Meeus, “Astronomical Algorithms” and “Elements of Solar Eclipses”.
• Weather: Apple Weather for upcoming dates. The climate statistics contain modified Copernicus Climate Change Service information (ERA5, CC BY 4.0). Terrain elevation: ETOPO 2022 by NOAA.
• Meteor showers: radiant and zenithal hourly rate from the working list of the International Meteor Organization.
• Satellite orbits: CelesTrak, based on data from the 18th Space Defense Squadron.
• Light map: 2025 atlas of artificial sky brightness by David J. Lorenz, from NOAA VIIRS data.
• Photo tips: exposure values after Fred Espenak.
• Maps: Apple; the notices are shown on the map.

Privacy

No account, no advertising, no tracking. Everything the app sends over the network is listed in the privacy policy.