What Are Shooting Stars?
Shooting stars - you may have seen one. Learn what this phenomena is all about.
They are one of the wonders of the night sky: luminous, bright streaks across the blackness of space. If you’ve ever seen one, you’ll appreciate just how spectacular nature can be. But the sight may have also left you wondering just what this phenomena is all about. These bright streaks are called shooting stars, but the name is a little misleading. These shooting objects are not stars at all but rather meteors.
Meteors are actually debris from comets. So, what is a comet? A comet is a massive ball consisting mostly of dust and snow that travels through the universe on a pre-set orbit. As it approaches the sun, its surface warms up, and it releases dust and gases. The radiation pressure of sunlight pushes the solid material back in a glowing tail of dust. The comet thus leaves in its wake a glowing tail of debris. These are known as meteoroids. Most meteoroids are too small to become visible in the night sky.
In a few cases, the comet’s orbital path crosses that of the earth. So, the earth meets the same trail of dust each time it passes through the comet’s orbit. When this happens, the tiny meteoroids plummet into the atmosphere at high speeds. As the larger ones fall, they heat up and burn. This produces a white hot streak across the sky, and it is this effect that is known as a meteor or a shooting star.
When the earth passes a comet’s path, the meteors appear to shoot out in all directions from the same point in the sky. This is called the radiant. From these radiants, meteor showers fall at different times of the year. The Perseides shower--so named because its radiant is found in the Perseus Constellation--can be seen around August 12 or 13. At this time, you can see as many as 60 meteors fall in the space of an hour. The Orionodes shower is visible about October 21 and is said to be caused by meteoroids from Halley’s Comet. But if you miss these, don’t despair because scientists estimate that there are about 200 million visible meteors in the atmosphere every day. Almost all of them burn up before reaching the ground. So, only about 500 meteorites each year reach the earth. Of these, few are recovered. One that was recovered in 1983 in Wethersfield, Connecticut, crashed through the roof of a house and its second and first floor windows, coming to rest in the living room. It weighed six pounds and was about the size of a grapefruit. Remarkably, this was the second time in 11 years that a meteorite had crashed through the roof of a house in Wethersfield. The chances of one falling through your roof is, however, extremely remote.
So, rather than worrying too much about the dangers of a meteorite collision, why not go out and actively search for a meteorite: the sight is sure to impress you.