I want to state the knowns first and then I'll need a little assistance to finish this out, as I don't know the necessary formulae. S = Average Star with 1 solar mass (think all values equal to Sol) P = Planet with 0.01 Jupiter Mass A = Albedo of 0.333 D = 1 AU H = Specific Heat Capacitance of Average Granite Ok just to make everthing easier to deal with P has no atmosphere, no moon, and is tide locked with the S, In addition, the surface is perfectly smooth, has no axial tilt and no orbital eccentricity. How much thrust in terms of Solar Sail effect would P experience? Would this be significant enough over the course of time to allow P to migrate further out from the star? If is would allow for this migration, would if not be possible that a large sum of dark energy is nothing more then large scale effects of solar sail.
The 'solar sail effect' is due mostly to enegetic particles ejected from the Sun. Their rate of emission is largely connected to sun-spot activity, and varies. I don't think these particles travel past the heliosphere, the area of the solar system that Voyager 1 is now entering. I do not know if their impact could effect planetary orbits over time, but do remember their effect would be miniscue on something with the mass of a planet. No, it could not explain Dark Energy. Dark Energy is a hypothetical substance used to explain the apparent accelerating expansion of the universe OVER VAST DISTANCES. For example, the universe around us for many millions of light years is NOT expanding, it is collapsing. Our local group of galaxies, including the Milky Way and the Andromeda Galaxy, is moving toward the center of the Virgo cluster at one million miles per hour. The center of the Virgo cluster is 50 million light years from Earth. The Virgo cluster, plus several other large clusters, are speeding towards a gigantic unseen mass named The Great Attractor. Gravitational attraction is the only known mechanism to explain this collapse, but there is not nearly enough mass present to generate the needed gravity. Then we need Dark Matter, and a LOT of it. Oh, well.
There are many sources of drag. The push from the solar wind would most likely be one of the lowset. The effect of tides from the (S) would be the major contributing source of drag. This would slowly move the planet to higher and higher orbits. This is what happens in a two body system.. Add more planets and the greatest influence is the resonance frequency of the orbits. The planets in most 3 body systems will constantly change orbit. 3 body systems can become chaotic. In this situation solar winds could produce major orbital changes. The secret to moving orbits is time. Estimates show that a 50km wide rock in a controlled orbit can move Earth out to the orbit of mars within 10000 years. The amount of energy expended over this time is very small, the Earth flinging mass can even be powered by solar wind (if it actually works). But most likely powered with nuclear power. We could move both our planet and solar system to some place a lot safer. We are already on a gigantic space ship. We just have to learn how to fly it...
