Dust particles larger than about one 100,000th of a centimeter in diameter form a large disk-shaped cloud that orbits the Sun between the orbits of Venus and the asteroid belt. (This cloud produces zodiacal light.a) Forces acting on these dust particles (called the Poynting-Robertson effect) should spiral most of them into the Sun in less than 10,000 years. Known forces and sources of replenishment cannot maintain this cloud, so the solar system is probably less than 10,000 years old.
Just as some rain falling on a speeding car strikes the front of the car and slows it down slightly, with the Poynting-Robertson effect, the Sun’s rays strike tiny particles orbiting the Sun, slowing them down, so they spiral into the Sun. Thus, the Sun’s radiation and gravity act as a giant vacuum cleaner that pulls in about 100,000 tons of micrometeoroids per day. Disintegrating comets and asteroids add dust at less than half the rate it is being destroyed.b
A disintegrating comet becomes a cluster of particles called a meteor stream. The Poynting-Robertson effect causes smaller particles in a meteor stream to spiral into the Sun more rapidly than larger particles. After about 10,000 years, these orbits should be visibly segregated by particle size. Because this segregation is generally not seen, meteor streams are probably a recent phenomenon.c
Huge quantities of microscopic dust particles also have been discovered around some stars.d Yet, according to the theory of stellar evolution, those stars are many millions of years old, so that dust should have been removed by stellar wind and the Poynting-Robertson effect. Until some process is discovered that continually resupplies vast amounts of dust, one should consider whether the “millions of years” are imaginary.