Absolutely bizarre lights over the Pennines - three witnesses, no explanation

This happened about three weeks ago (23rd November, around 10:45 PM) near Hebden Bridge in West Yorkshire. I was walking the dog with my partner, and our mate Tom was visiting. Clear night, cold as anything, full moon. Suddenly the whole valley lit up - and I mean LIT UP - in this deep blue-green colour. Not like car headlights, not like lightning. The colour was wrong for anything natural.

It lasted maybe five seconds. The three of us all saw it, all looked at each other with that 'did you just...?' expression. Tom's a physicist (proper proper one, works at a research facility) and he was completely stumped. His words: 'That's not bioluminescence, not ball lightning, not reflective properties I can identify. I've got no framework for that.'

We rang the local police non-emergency line. They hadn't had any other reports but said they'd 'note it.' Pretty dismissive, to be honest.

Anyone else in Yorkshire seen anything similar? And has anyone got experience identifying what this might be?

Hebden Bridge is right near some military training areas. Could've been flares from RAF exercises - they do night training runs and use all sorts of coloured parachute flares. Blue-green would be unusual though. Worth checking if there were any scheduled flights?

Bioluminescence doesn't just happen in the sky above Yorkshire, mate. You're thinking of atmospheric phenomena. Could be a rare upper-atmosphere discharge - something like red sprites or blue jets? Your physicist mate should've recognised those, but they do occasionally appear in unexpected colours under certain electrical conditions.

This is genuinely interesting because you've got three independent witnesses and a credible observer in your mate the physicist. Have you tried contacting the British UFO Research Association? They track sightings and can help identify common explanations. Not everything is alien, but some things genuinely are unexplained.

his words: 'That's not bioluminescence, not ball lightning, not reflective properties I can identify.'

I'm from Hebden Bridge originally. The Pennines get weird atmospheric conditions because of the geography. I've seen some genuinely odd light effects up there - weird refractions, strange fog patterns. Not saying that's what you saw, but the landscape plays tricks on your perception more than you'd expect.

Got any photos? Even if you didn't think to take them at the time, sometimes dashcams or security cameras nearby capture these things. Worth checking local businesses or asking if anyone recorded it.