This story took place in a farm in between Loncoche and Pucon in Chile, around the late 1960s, and it happened to my mother and her sister who where around 13 at the time. Being Chile in the 1960s in the middle of nowhere, there wasn't any electricity, so no TV, and the most common pastime was looking at the stars. (You should see this place; you can see a crystal-clear sky.)
They didn't have a telescope, so they used some very powerful German binoculars. One night, my grandma spotted this strange ball floating in the sky, about the apparent size of a full moon. She called my mum to the window so that she could also take a peak. My mum describes it as a ball, with no defined lines, like gas, and with changing colours.
My mum went outside with her sister so they could take a better look. My grandma by that point had lost all interest in the thing. Once outside the house, they just stayed at the threshold of the door, looking in awe. Suddenly, they both heard something buzzing by, really fast, and my mum dismissed it for a bug or something, because whatever it was it passed by them really fast and close. Then my mum looked to her right to see what made the noise and saw a small light going down the hill (the house is on top of a hill). The really crazy bit is that as the light went down the hill, it also got bigger in size, until it reached a river, which is 2km approximately from the house.
By then the spaceship (because by this point it has a defined, geometrical shape and windows) was the size of a two-story building. My mum and my aunt just kept staring, dumbfounded at this unexplainable event. They saw how this ship tore the branches off the river's trees. Then the ship stopped moving, but the top part started rotating, and that's when this incredibly strong light illuminated them both. She describes it almost as a laser in intensity. This scared them blind, and they both automatically jumped inside the house and closed the door. They went running to my grandpa and told him what happened. And then he said a phrase that could have come from the very US government: "It must be a tractor."
And nothing happened next. Few people knew what a UFO was in Chile back in those days, and my mother wasn't the exception. The reason that my mother chose to tell me this story is ironic in itself. My cousins and I used to go to this farm every summer, and on one summer my oldest cousin started scaring me with UFO stories. When I got home after the summer, I asked my mum if there is such a thing, and far from telling me that this is not true, she told me this story! Ever since then, I have researched for years in the subject, and I consider myself a ufologist. My grandpa is still alive and doesn't remember the incident, and he is still a bona fide skeptic.