Scientists Prove Sunlight Alters Asteroid Orbits

About eight years ago, scientists postulated that something called the "Yarkovsky effect" (or YORP, for short) might be subtly effecting asteroids' orbits, forcing them into the inner solar system. The effect itself was logical enough--a subtle force changes the asteroidal spin rate, thereby changing its path--but the cause was unusual: sunlight. These types of seemingly fantastical theories abound in the sciences; it's hard to tell--with all the strings, the wormholes, dark matter, and new dimensions--which is just flight of fancy and which is reality. Last week, English and Finnish scientists showed that their feet are firmly on solid ground when they proved that sunlight does, in fact, alter asteroids' spins.

Asteroids are usually lumped together with comets and meteors, since they are all basically composed of the same goods, though the method of their formation is very different for each. Comets are composed of a hard ice/rock nucleus. As they near the Sun, the nucleus gets warm, causing the ice to vaporize and some of the nucleus to break off. Some of this dust is blown back by the solar radiation, causing the appearance of a tail. The term "asteroid" is mostly a catch-all: Asteroids are just rocky objects, plain and simple. They can vary in type from being merely a loose collection of rubble, to being a solid chunk of rock or metal, and their diametrical sizes can vary from 1 to 700 km. across. Meteors are pieces of comets or asteroids that have broken off (due to collisions) or been left behind. Once they enter the atmosphere, they become meteorites, or, as we tend to know them, "shooting stars."