Blue flashes in he sky

They're some interesting calculations there Rice, but the camera flash theory just doesn't fit the bill for me, given the amount of people who saw them.

David the rule of thumb is just a very old guideline used by radio men in that case they used the factor 1.3 in front of the square root but I have used 1.1 for visual estimates since the range of a VHF radio wave would be sligthly longer than visual line of sight.

Mariners/Aviators and navigators probably use something similar.

Re the flash camera idea - yes it is a very long shot.
However I do remember being on holidays In Spain and noticing flashes while sitting outside late at night and eventually seeing the source as somebody with a camera a few hundred yards away.

Anyway there ere other things that produce BIG Blue flashes such as HT power lines, granted Corona discharges are less likely from a power line with dirty insulators on a clear dry night. They tend to happen in damp or misty conditions.

I have never heard complaints but I imagine something like a bat flying between the wires of a HT 33KV or 10 KV line could provide a path for a discharge. I wonder has any naturalist ever complained about roasted bats being found in their vicinity.

(Considering what I have just written maybe I should start by looking in my own belfry?)

I've seen this phenomenon a number of times, mostly it happens while I'm looking down into the eyepiece or at my charts. Everything around me gets momentarily illuminated about as bright as a 1st quarter Moon would be. It happens pretty fast.

The first few times I thought it was an overhead iridium flare, but when I checked the next day, there wasn't one anywhere near me. It's happened a few times while looking up and scanning the sky too, and it looked like an even glow all over with no area any brighter than another.

Strange world we live in.

The first few times I thought it was an overhead iridium flare, but when I checked the next day, there wasn't one anywhere near me.

That doesn't mean there wasn't one Draco! There are some satellites (even Iridiums) that are defunkt, but still orbiting. Most of the ones still in operation have known trajectories and period of spin, therefore are easier to predict a 'flare'. The defunkt ones mostly spin erratically. That is why it is a widely accepted theory (among a few) that its reflecting space junk catching sunlight momentarily that causes these flashes.

Seanie.

Well now, that makes a lot of sense. I was lucky to have seen the flashes, then!

There's a website showing a simulation of how much debris is actually floating around up there, and it looks like a warm of insects around the globe. (A search on 'space junk' will probably turn something up.) Interesting stuff, for sure.