Idiot question. Go read up on what a comet's tail is. Gad, is this what uncensored content is all about, is idiots spouting idiocy? Give me youtube.

Bandit they did this years ago... and... its flat!

Okay, you got me....... what is YOUR answer? If you want to prove the world is flat (which you question would work exactly the same) get your self a powerful laser and set it up on the beach of a lake perfectly horizonal, sending the beam across the lake. Then go out and measure the lasers height at different distances across the lake. The larger the lake the better by the way. Then you get back to us on your results Okay......