Malcolm Owen, AppleInsider:

The patent application for “Light-based Shielding Detection,” published by the US Patent and Trademark Office on Thursday and originally filed in December 2017, describes a ‘sunscreen detector that could be used on a portable device, which Apple suggests could be a wearable device.

Imagine a sensor on your Apple Watch that could measure UV radiation and warn you when you’ve been in the sun too long. I love this idea.