Perhaps a total solar eclipse? Especially so when seeing half the solar system lined up neatly in a row with the sun and moon (and a comet in case of the recent April 2024 eclipse in the US), and truly feeling that one is riding on a chunk of rock hurtling through space, tethered invisibly to that impossibly distant mass of gas and plasma like a ball at the end of a rope...

Still get frisson every time I think about it ;)