Currently available via TestFlight on iOS, the app aims to provide personalised, accurate estimates while remaining conservative for safety.
It appears as small and medium widgets for the user’s home screen. The founder has made it available in the public domain, and its code is on GitHub for anyone to clone.
App features
Sun Day tracks real-time UV index from the user’s location along with sunrise and sunset timings. It calculates vitamin D based on UV, skin type, and clothing.
Additionally, it shows the current phase of the moon using astronomical data based on your local time and date.
All the information gets automatically synced to the Apple Health app, which helps users to have wellness data in one place.
How does it work?
Sun Day shows the UV index at the user’s location along with details like cloud cover, sunrise, and sunset timings. There are six options for the skin types, ranging from Type I (125%): Very fair, always burns—highest vitamin D production, to Type VI (20%): Very dark, never burns.
Clothing also plays a role, varying from nude (100%): full body exposure, to heavy/fully covered (5%): winter clothing. The app calculates the length of time the user can expose their skin to sunlight before it starts to burn.
The development comes days after Dorsey launched a new messaging app called Bitchat, which lets users chat without internet access or mobile networks. Bitchat lets users send messages over short distances using Bluetooth, making it useful in crowded areas like concerts or festivals where mobile networks often fail.
