Answer :
A comet could change course when passing a planet due to:
- Gravity Forces
The four outer planets are composed of mostly gases and:
- Hydrogen and Helium
Since radio waves, microwaves, infrared rays, visible light, ultraviolet rays, X-rays, and gamma rays are all emitted by the Sun, you could assume that the Sun emits a large part of the:
- Gamma Rays Spectrum