Young-earth "proof" #7: Space dust would be vacuumed out of our solar system by the Poynting-Robertson effect in a few thousand years. Since that is not the case, the earth is very young.

7. The Poynting-Robertson effect is an effect that sunlight has on small dust particles orbiting the sun. The continuing absorption of sunlight robs the dust particle of more and more of its angular momentum, giving it a tendency to slowly spiral into the sun.

Based on the Poynting-Robertson effect alone, particles 0.001 cm in diameter located at a distance equal to that of the earth's distance from the sun (one AU) would spiral into the sun in about 19,000 years; particles 0.0001 cm in diameter would require less than 2,000 years. (Strahler, 1987, p.145)

Slusher, in his book Age of the Cosmos (a 1980 ICR technical monograph), argued that the presence of such fine dust in our solar system limits its age to less than 10,000 years.

However, Slusher has overlooked several things. Reflected sunlight (as versus absorbed light for the Poynting-Robertson effect) applies an outward force on dust particles. As a particle gets nearer to the sun, this outward radiation pressure increases faster than the force of gravity pulling the particle in (Strahler, 1987, p.145). Certainly, that would have an important effect on any time calculations.

Another point overlooked by Slusher is the gravitational effect the planets would have on dust spiraling in. Many dust particles would be kicked into elliptical orbits which would greatly lengthen their time in space.

Still another effect "...overlooked by Slusher is trapping of particles by gravitational resonances with the larger planets (Alfven and Arrhenius, 1976, p. 81). So trapped, particles could remain in stable orbits indefinitely." (Strahler, 1987, p.145).

What about those comets which sweep through our solar system every now and then? Comets usually have two tails, one of gas and one of dust, and those tails often extend many tens of millions of miles across space. Comets would contribute quantities of new dust (Dutch, 1982, p.31). Collisions in the asteroid belt, or even major asteroid impacts on the smaller planets or moons, would also contribute some dust to the interplanetary spaces.

Therefore, the Poynting-Robertson effect provides no panacea for young-earth creationism.