I've had two occasions of observing orbs purely by chance. (Burnt into my memory!)
First time, was overhead - where I live, one orange orb due south over Warminster, heading in zig-zag moves towards me at distance, then it seemed to disappear. I turned to come back inside my house (as I was out in my garden at the time, at night), and by chance I happened to look upwards (just to look generally above me), and another orb was directly overhead. It moved across and over the valley towards the south, then I could see that it joined (literally) up with the previous orange orb, and slowly moved out of eyesight following the path along the valley.
The second time I witnessed an orb (few years ago now), was when I was out for a late night country walk - must have been about 11 O'clock at night. Walking along a road along the edge of a local deep wooded valley, I happened to notice this bright orange orb right down in the bottom of the valley (I knew the valley well and the exact position it was in), which was hovering over a footpath crossing point over a small stream which runs along down the valleys length, and about 500 ft below the road, so it must have been quite a large glowing orange coloured orb, and I think I saw that it had a centre part to it - but I'm not certain about that.
Why on earth I strangely had seemed to have turned my head away (from memory), and found myself questioning myself as to why I had not stopped and observed it - which in itself is not like me to just ignore seeing something like this - I don't have the answer to. Next all I remember was walking along further at further - lower point along the road, where there is located a Pub, I carried on home totally wondering what had happened!
Next day I walked along the same part road, and happened to spot the publican outside clearing up the tables I believe. So I stopped and asked him if anything odd had happened lately. He replied, "yes, it's funny you should ask, some patrons had mentioned seeing coloured lights down in the valley last night."
So, it wasn't hard to put two-and-two together and conclude that it had something to do with what I had encountered.