Just think about the concept and then think about things you might have heard about in the news or read in science magazines or eZines.<quoted text>
If you were my teacher I would drop out
No one was there to SEE it, but we know without doubt that a humongous meteor fell to the earth just off the Yucatan peninsula 65 million +- years ago and ultimately caused the demise of the Dinosaurs and almost wiped out all other life on earth. Nobody was there, but a meteor fell to the ground in Arizona about 50,000 years ago and made a crater almost a mile across. We weren't there to see it, but we know the earth once had just one super continent we now call Pangaea about 225 million years ago.
And there are literally millions of things that science has found out about our world and universe because we train ourselves to find and interpret data and physical evidence that almost any event leaves behind, or we build instruments to analyze stuff we can't naturally see/hear/taste/smell/etc.
Not meant to be disrespectful, but from the comments I read you don't really understand science and how it works...you are the dream of fundamentalist recruiters.