About 2 years ago I had just finished watching a video with my mother around 1am in early January. We witnessed a very bright blue light that illuminated the entire sky like daylight, casting shadows of the trees across the yard. I suspect that we had just witnessed an event related to ufos but have nonetheless worked a few theories: Theory #1- Helicopter spotlight. I don't really think it could be this one, the light strobed brightly slowly and a spotlight doesn't strobe. Also, there was no wind from the propellers and no noise. Theory #2- transformer blowout. This couldn't have been the case because all of our cables are below ground and there are no transformers above ground in the area. Theory #3- Tugboat spotlight. Again, spotlights don't really strobe. Furthermore, the river is a half mile away and any light coming from there is buried by dense forest between our house and the river and for the light to be as bright as it was, there is no way the tugboat light could have been bright enough. Theory #4- meteor. Although it seems more likely for a bright burst of light, it would have been for only a moment and not a prolonged strobing. Theory #5- lightning. Thunderstorms, in my experience, have never produced lightning this bright. It was literally as bright as daylight but all blue and slowly strobed. I would like to know if anyone else has any theories that could explain this phenomenon or if you think I had witnessed an extraterrestrial source. My sister, in another room in the house, also witnessed this event independently from my mother and I. You mentioned a fireball and a very close lightning storm. I have seen fireballs before. I admit that they are very bright and had it been one bright flash of light, I may have agreed with you. However, the light disappeared and came back just as brightly about 5 times with between 1 and 5 second intervals between each illumination. Very close thunderstorm, possible. It would be VERY strange lightning to behave in such a manner. There was no rain, no wind, no noise just completely still winter night and the blue light was only in the sky for around 2 minutes. Yes, I was very curious to see what it was, but could not locate a source for the light. At one point it seemed to be immediately overhead and then later seemed to be more over the neighbors house. We looked around but couldn't figure it out. It was about 2 years ago, so my memory may be adding time to the event, it's hard to gauge time after so much of it has passed, lol.
An object as bright as daylight would have been witnessed by many people, unless you live in the wilds of Greenland or Siberia. In fact if you had normal night-time lighting on in the house and a light as bright as daylight appeared outside it would probably temporarily blind you until your eyes adjusted to it.
Edit:
If it was 2 minutes it was too long to be a meteor, but from your description it seems like you did not see the object that was creating the light. 2 minutes is a long time, weren't you curious to see what it was?