The first argument is more or less understandable (still wrong): you can’t just propel yourself upwards at your earliest convenience to reach the moon, you have to play around with orbital mechanics.
If your friend’s idea of a moon-worthy vessel is an unsteerable rocket with infinite fuel and a chair strapped to it… well the odds are effectively zero.
The second argument? bro, last time I checked the moon was still orbiting Earth
The friend should play Kerbal Space Program. It will be a fun way to show that yes, it’s really hard, but it is possible to play around with orbital mechanics and get to the moon.
And then it will show that an unsteerable rocket with infinite fuel and a chair strapped to it is also possible, just really really hard.
I imagine the latter isn’t too hard, you just have to get it right just before leaving the atmosphere (quick saves help); however, isn’t landing (not crashing nor rolling around) on the Mün without steering straight up impossible?
Though I can see some rocket landing on a planet with an atmosphere…
