If you spend much of your time in The Witcher 3 looking at the ground for fear of having to nod at or otherwise acknowledge some dolt who's walking the opposite way, then you're missing out on a whole universe of fun. The sky in The Witcher 3 is a sight to behold, gracing us with convincing dynamic weather conditions and some of the best sunsets in video games. But hang about by some beautifully stark lakeside until after the sun goes down (look out for those drowners), and you should be able to spot some shooting stars too. There's no particular place where this happens more often, so it's just a matter of luck whether you see one or not. But while you may be going 'ooh', 'ahh' and making a wish at the sight of them, just remember that Geralt finds what you're doing a complete waste of time, as revealed by this beautiful passage from the books:
"A star fell, a brief flash of lightning illuminating the black firmament, flecked with unmoving dots of light. The Witcher made no wish".