I can hardly explain it because they do not speak English
but take into account the image.
https://goo.gl/6bpxXs
when the planet is colliding with purple sprite, and you see the player collides with purple sprite,
the angle of the planet will go to the direction of player,
and gravity will equal planet.angle-180
to move from planet to planet looks bad,
so I had to put that when the player
sprite collides with purple,
the vertor Platform will be equal to 0
in the case of noncircular lands
yellow sprite that is responsible
when the player collides with yellow sprite
gravity will be equal to the angle of the yellow sprite
That's the basics, sorry for my bad English