Five Top Cosmic Myths
How much do you know, really know, about astronomy? Look at the statements below and pronounce them "true" or "false." Are you sure enough of your answers that you'd bet on them? I've compiled a list of five cosmic topics and most folks fall prey to at least one of them!
5 There is no Gravity in Space
The first statement, that there is no gravity in space seems to be proved true by all those NASA videos showing shuttle astronauts floating around inside and outside of the space shuttle, and by the popular term "zero g." But, it is a long held myth. Shuttle astronauts are in free fall, meaning that they are in reality "falling" around the Earth. In effect, they are falling toward the Earth, but moving sideways enough to continuously miss it. All the planets are held by the gravity of the Sun. The Sun is affected by the gravitational influences of other cosmic bodies. Gravity, goes on forever.
Our next statement that the full moon looks larger on the horizon because the air magnifies it turns out to be another long held myth. The full moon does look larger on the horizon, but it is a trick being played on us by our eyes!
This visual trick is called the Ponzo effect, named after the person who identified this illusion. When we have objects on the horizon (trees, hills, buildings) to use as size comparison, the moon does appear larger than when it is high in the sky.
The next statement deals with meteors and whether they are hot when they reach the ground. Again, it makes sense that this would be true. Well meteors do glow hot while in the atmosphere but that's not the whole picture.
The surface of the meteor melts from the heat of the air in front of it. The high velocity provides the energy for all this heat and light. When friction causes it to slow to below the speed of sound, all that heating stops. It's still high in the atmosphere, and takes several minutes to fall to the ground. Remember the meteor has been in space, and the inside is very cold, any melted parts have blown off The air the meteor is now traveling through is also very cold.
All these things together mean the rock is not hot when it hits the ground, some have been found covered in icy frost!
Our next statement also deals with meteors, which have been called falling or shooting stars by many cultures. But, they have nothing to do with stars. Meteors are pieces of asteroids or comets that enter the Earth's atmosphere.
Our last statement is a favorite. Are the Earth's seasons caused by varying distances from the Sun? It is true that Earth's distance from the Sun does vary, but it does not cause our seasons. Rather, seasons are caused by the Earth's 23.5 degree tilt on its axis. During our winter, the northern hemisphere is tilted away from the Sun, even though at that time we are also closer to the Sun than during summer! When we have summer, the Earth's northern hemisphere is tilted toward to the Sun.
If you got caught on a few of these, don't feel bad, most people do! Instead, challenge someone else and gloat because you know!
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Kathy Miles, Author, and Chuck Peters, Systems Administrator
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