Why Are There Different Kinds Of Clouds?

Here is how clouds are formed: Warm air, laden with moister, rises into the sky. When it gets to a certain height, the warm air cools. At the cooler temperatures it can no longer hold all its moisture in the form of water vapor. So the extra moisture changes into small drops of water, or bits of ice and this forms clouds.

No two clouds are exactly alike, and they are always changing their shape. The reason we have different types of clouds is that clouds formation takes place at different heights and temperatures. And clouds will be composed of different particles, depending on their height and temperature the highest clouds are called “noctilucent” clouds. They may be up as high as 30 to 59 miles! The next highest are called “nacreous” or “mother-of-pearl”. They are 12 to 18 miles high. They are very thin, beautifully colored clouds composed of dust or before sunrise.

The next highest clouds, which are five or more miles above the earth, are called “cirrus” clouds, “cirrostratus” clouds, and “cirrocumulus” clouds. The cirrus is feathery and threadlike, the cirrostratus is thin, whitish sheets, and the cirrocumulus is small, round clouds which from “mackerel” patterns in the sky. All these clouds are made of tiny bits of ice.

Lower clouds are made of little drops of water. The highest of these, the altocumulus clouds, are about two to four miles above the earth, and are made of larger, rounded masses than the cirrocumulus clouds. At the same levels are altostratus clouds, which often cover the whole sky with a grayish veil through which the sun and moon shine as spots of pale light.

Lower still, about a mile high are the stratocumulus clouds, large and lumpy. At the same level are the rain clouds, the nimbostratus, thick, dark, and shapeless. Very low, less than 2,000 feet above the ground, are the stratus clouds, which are sheets of high fog. Two other kinds of clouds, the cumulus, and the cumulonimbus, are the big, fat, “cauliflower” clouds that bring thunder storms.

Why Do Astronomers Think There May Be Life On Mars?

As you know, scientists are now conducting all kinds of experiments to see if life can be found anywhere else in the universe. Naturally, it is easier to explore our own solar system for signs of life than it is to probe outer space. And one of the places where some scientist believe a form of life might be found is the planet Mars.

Why did they pick Mars? Well, Mars is considered to be a sort of twin of our own planet earth. It is the next planet beyond the earth is distance from the sun. Mars is about half the diameter of the earth and it rotates around the sun in just less than two years. But Mars has a day that is almost equal in length to our day here on earth.

In observing Mars, astronomers have noticed certain things that indicate a form of like may be possible there. First of all, Mars has seasons like the earth. In fact, as the season change on Mars, in the spring and summer, and the color changes from bluish-green to yellow. Could this be vegetation?

Astronomers also believe that there is at least a small amount of water vapor in the atmosphere of Mars, and this would helpful in supporting life. Then, too, in 1887 an Italian astronomer, Giovanni Schiaparelli, reported seeing marketing on the surface of Mars that resembled canals. “Could these have been built by Martians in order to carry water from the polar region to the desert areas?” scientists wondered.

However, in the summer of 1965, the Mariner IV capsule completed its historic 325-million-mile journey to take photographs of the planet. These, radioed back to the earth from the capsule, indicate that if life does exist on Mars, it is of a very low order – moss, or lichen, or fungus. Any life would have to survive in a desert-like environment, and in an atmosphere that has little or no oxygen and only traces of water vapor. But many scientists still believe that when man finally lands on Mars, he will find some form life there.

What Is A Comet?

At one time, the appearance of a comet caused people to tremble with fear. They believed that comets were evil omens foretelling plagues, wars and death.

Today, we have a pretty good idea of what comets are, though we still don’t have all the answers about them. When a comet first appears, it is seen as a tiny point of light, though it may be thousands of miles in diameter.

This point of the light is “the head”, or nucleus, of the comet. Scientists think it is probably made of a great swarm of bits of solid matter, combined with gases. Where this matter originally came from is what still a mystery is.

As the comet approaches the sun, a tail usually appears behind it. The tail consists of very thin gases and fine particles of matter that are shot off from the comet’s nucleus of the comet are third portion, known as “the com”. It is glowing cloud of matter that sometimes reaches a diameter of 150,000 miles, or even more.

Comet tails are very different in shapes and size. Some are short and stubby. Other is long and slender. They are usually at least 5,000,000 miles length. Sometimes they are almost 100,000,000 miles longs! Some comets have no tails at all.

As the tail grows, the comet gains in speed because it is nearing the sun, moving toward it head first. Then a curious thing happens when the comet goes away from the sun, it goes tail first with the head following. This is because the pressures of light from the sin drivers off the very small particles from the comet’s head to from its tail, always in the direction away from the sun.

As a result, when the comet goes away from the sun, its tail must go first. During its journey away from the sun, the comet gradually slows down and then disappears from sight. Comets may remain out of sight for many years, but most of them reappear eventually. Comets make trip after trip around the sun, but they may require a long time to make a single revolution. Halley’s Comet, for example, takes about 75 years to make its trip around the sun.

At present, astronomers have listed almost 1,000 comets, but there must be several hundred thousand comets in our solar system which remain unseen!

What Are Falling Stars?

For thousands of years men have looked up at “falling stars” and wondered what they were and where they come from. At one time it was believed that they came from other worlds.

Today we know that they are not “stars” at all. We call them “meteors.” They are small, solid bodies which travel through space, and which may also pass through the earth’s atmosphere.

When meteors come within our atmosphere, we can see them because they leave a fiery train of light. This is caused by the heat made by the friction, or rubbing, of air upon their surfaces.

Strangely enough, most individual meteor particles are quite small, about the size of a pinhead. Occasional meteors weigh many tons. Most meteors are destroyed entirely by heat as they pass through the earth’s atmosphere. Only the larger meteors fragments ever reach the earth. Scientists believe that thousands of meteors fall to earth each day and night, but since most of the earth’s surface is covered by water, they usually fall into oceans and lakes.

Meteors may appear in the sky singly and travel in practically any direction. But meteors usually occur in swarms of thousands. As the earth travels in its path around the sun, it may come close to such swarms of meteors, they become fiery hot upon contact with the upper layers of the atmosphere, and we see a “meteoric shower”.

Where do meteors come from? Astronomers now believe that the periodic swarms of meteors are the broken fragments of comets. When comets break up, the millions of fragments continue to move through space as a meteor swarm or stream. The swarms move in regular orbits, or paths, through space. One such swarm crosses the earth’s path every 33 years.

When a piece of meteor reaches the earth, it is called “a meteorite”. It has fallen to the earth because gravity has pulled it down. Far back in Roman such an important even that is was recorded by roman historians!

What Is The Brightest Star?

Have you ever looked up at sky and tried to find the brightest star?

You may imagine that the number of stars you can see is countless. But the most that can be seen without a telescope are about 6,000 stars, and one-quarter of them are too far south to be seen in North America.

Ever since the days of the Greek astronomers, 2,000 years ago, the stars have been divided into classes according to their magnitude or brightness. Until the invention of the telescope, only six magnitude, or degrees of brightness, were recognized. Stars of the first magnitude are the brightest, and stars of the sixth magnitude the faintest. Stars fainter than the sixth magnitude cannot be seen without a telescope. Today, stars can be photographed with modern telescopes down to the 21^st magnitude.

A star of any given magnitude is about two a half times fainter than a star of the magnitude above it. There are 22 stars of the first magnitude, the brightest stars, and the brightest star of all is Sirius, which has a magnitude of – 1.6. This makes Sirius over 1,000 times brighter than the faintest star that can be seen with the naked eye.

The lower we go down in magnitude, the more stars there are in that class. Thus, there are 22 stars of the 1^st magnitude and about 1,000,000,000 stars of the magnitude.