Ok so I don't know how to explain this experience I've had. I gotta say first that I'm not really a believer, not that it matters, but I'm not superstitious. I don't know how relevant this is, but my mother died of a heart attack in our house in 2009. Anyways, I live in Guanacaste Costa Rica in a very small town with few people and houses. I always go to bed really late (way past midnight). I sit in the living room surfing the web in my computer (with the all the lights off), I've done it for years.
When I am done, I shut down the computer and go straight to bed. However, on the occasion I'm describing I took my computer to my room and continued watching a movie on my bed (it was about 1 in the morning). My room door is half wood, half glass (the ones that are not completely see through), and there's a little entrance with a mirror that connects it to another room (which is always empty). I live with my dad, but that night I was alone, he was in the capital. About 5 minutes after I lay on the bed (my view was directed towards the door by the way), a big ball of light dissolved into the other side of the window. I say dissolve because it didn't just pop up; it appeared gradually from small to big (I don't know how to explain it). It sort of grew into existence, if I had to describe the size, I'd say it's about the size of the bottom of a 2 litter coke bottle. It moved slowly, but steadily to the right (from my perspective); it had sort of a tail (not a tail, but like a comet, only that is was short, like the body dragged), and then it vanished the same way it appeared. It disappeared from big to small. I freaked out, and I immediately closed my computer, but kept looking in the pitch black. 5 seconds later it reappeared like it did before, but trailed to the left and disappeared in about 4 seconds. I couldn't believe my eyes, you know that feeling after you've seen something that is strange and you question whether you actually saw it, well I got another chance to see it again. A few seconds later it appeared the same way in the middle of the window and it moved up. It froze there in the upper part of the door window, where I could still see more than half the body. It stayed like that for at least ten seconds and then vanished from big to small like the other times. I never ever saw it again after that. I kept looking to see if it'd return for at least 15 minutes. Then I, tried to fall asleep (unsuccessfully, I fell asleep about 3 hours later) I'm sorry, but I didn't get the guts to stand up and open the door when it was occurring
I want to clarify that this wasn't like when you direct a flashlight to a window, where you see how the light is hitting the window. This was like the light was floating in mid air but not making contact with the window or anything for that matter. It was very bright and white. I might have dismissed it if I hadn't actually seen it three consecutive times. This was the strangest thing I've seen with my own eyes. I had other very strange experiences in this house, but that is the only visual I've ever had. There was no sound by the way.
Also, there is not a single angle in that window where the light could have come from outside the house. I just couldn't have come from outside, like reflection from a car or something.
Needless to say, I was very scared. Sorry for the long story.
