Gravitation(angular deflection of a planet from a massive star)

[ErwinMoses]

i was just thinking , a planet comes close to a very massive star but doesn't collide .how can i calculate the its angular deflection.?

i can calculate the velocity afterwards the deflection(given the initial and final perpendicular distances of its course from center of the star) using angular momentum principle,but how can i predict the behavior of the planet during such an event?

i am considering the planets and stars to perfectly spherical.
no idea how to start.

 

[mfb]

You can calculate the "orbital" parameters (even if it is not a proper orbit). The motion is a solution of the Kepler problem (=google keyword).

 

[ErwinMoses]

thanks.