I've actually seen several (they usually look like satellites, but you can tell the difference by their movement. Satellites don't turn!)
one that was very close (maybe 1 or 2 miles from what I could tell?), but since I have no idea of the objects size, it's really hard to say how far away it was
but it was about the size of the moon
slightly smaller
and it was shaped as a "plate" (
eh
like a round, flat cheese , but thinner
)

and "tilted" with the top facing me (so I couldn't see underneath)
anyway
it stayed in the air for 3 seconds before it "disappeared" (I could tell that it took of to the left in an incredible speed, but it was impossible to follow, and it was gone in a split second
And the effect of looking at its strong "whitish" light, and then having it disappear like that, made it look like it disappeared in a "black hole" in the sky, because of the contrast to the incredibly dark winter night
know what I mean?

It's like looking straight at a light and then when you turn away the light "stays" for a while).
And then after thinking about what had happened (for a minute or two), I turned around, and it was back in the same place, and did the same thing again!
So, just thought I should share that story with you guys!
I'm not saying that "they" were aliens (all I saw was an "object"), because it just seems "impossible" to travel to the closest inhabitable planet
even at light speed it's gonna take a lifetime or more!
But
what about something like this:
Vimanas?
I'm a sceptic, so I'm not saying they are, but it's at least "as" possible as aliens
isn't it?
I also would like to state that the only other place in THIS solar system with life (and by "life" I'm talking bacteria & microbes) is
Enceladus, one of Saturn's moons (note that this has NOT been proved in any way, and it's just my personal opinion
but wait and see!)
