One surprising thing is that many mountain tops seem to have mobile phone reception. They also often find themselves suddenly shrouded in mist.
Today’s invention is an app for a smartphone (something like this one).
Instead of showing people those stars which are invisible, the app in question would show the view, from anywhere on a mountain walk, which would be visible if the mist had not descended.
This could be a lifesaver for anyone lost, but also it might reduce disappointment for visitors who just happen to ascend on the wrong day to experience the scenic views they require.