What Are Shooting Stars?
Shooting stars are also known as meteorites and an amazing fact is that they are similar to the planet earth in composition than any stars in the whole universe! They are objects that were roaming in space which were attracted by earth’s gravity. If the size of the object is less than that of an ordinary boulder that is called a shooting star or a meteoroid, else it is known as an asteroid.
Their classification is not easy, but still there are three broadly defined groups shooting stars fall into on the basis of their composition. They are: (a) stony (b) stony iron and (c) iron. The stony meteorites are the most common and they are also known as chondrites. Radiometric dating has showed their age to be 4.55 billion years, which makes them almost as old as our solar system.
Why shooting stars are called so?
It is also being speculated how shooting stars got their names. Out ancestors were used to observing fixed dots in the night sky. They named them stars and planets. Then, there were some objects which puzzled them. They could not figure out how there could be light falling out from a place. They thought, perhaps, one of the stars was falling, and hence they got their now familiar name shooting stars!
Why is it that they light up in the sky?
A common myth is when meteoroids come in contact with earth’s atmosphere, their high velocities cause so much friction, thus producing a tremendous amount of heat, that they light up in the sky and we get our shooting stars or meteoroids. But this is not found to be true. Scientists say that bright line is caused by the ram pressure of the meteoroid and not friction. Ram pressure is the pressure exerted on a body when it is moving through a fluid (liquids or gases are fluids). For comparison we can think of a fighter jet flying at supersonic speeds. This pressure is so powerful that bigger meteoroids (or shooting stars) along with a bright line, also produce crackling noises as they travel through the atmosphere.
Ramjets are a recent phenomenon. How did our ancestors view the stars?
Our ancestors didn’t know shooting stars as we know them. In some cultures they were harbingers of evil or something bad while other cultures revered them as gods! A prevalent myth, that survives today is, that shooting stars fulfill wishes. And it is still not ascertained where this superstition originated from. During the Renaissance, shooting stars were thought of as an atmospheric phenomenon and it was only in the 1833 that a physicist and an astronomer from the United States who demonstrated that the shooting stars were a cosmic phenomenon.
The Romans and people in the Middle Ages were afraid of shooting stars. Evidences have been found, which demonstrate that those people would perform various rituals to please their angry gods. Shooting stars were though of as omens which showed that their gods were unhappy with the people.
Category: Astronomy, Science