is the sun moving simple harmonically up and down also?
I'm sorry, this doesn't make sense at all.
Are you asking if the sun exhibits a periodic motion?
What's 'up and down'...?The sun in an almost free space.3D picture.What's "up and down" in 3 dimensions...?
I interpret the original question asks if the eath's orbit around the sun is in a plane. If you use the center of the earth as a reference, it is not exactly. However, the center of mass of the earth-moon system orbits the sun in a plane (except for small perturbations due to the other planets).
isn't it that our galaxy travels in a dense area of asteroids once in 3 million years
Humm.... I think you need to re read your sources. We know little to nothing about that scale of motion, further, because the galaxy passes intergalatic material does not mean the the solar system will ever know about it. Perhaps you want to do some basic research and rephrase your question in a manner which makes sense.
I think he's reffering to the orbit of the Sun around the gallactic center. If the robit is slightly off the galactic lpane, it has been proposed that the simple harmonic motion taking us from "slightly above" the ecliptic to "slightly below" would cause the Solar System to pass through the thick of the gallactic plane tice per orbit. Some have theorised that these passages increase the likelyhood of nearby gravitational disturbances pulling asteroids out of there orbits. It is then supposed that these asteroids are responsible for the periodicity of mass extinctions.
Separate names with a comma.