Friday, September 18, 2015

What are stars made of?

Stars
Stars are formed from gigantic masses of hot glowing gases.  Hydrogen and helium are the most common gases in a star.  In the clearest night sky you might see a few thousand stars with unaided eye.  Every bright star is a sun, like our own sun.
Scientists tell us that a star is a huge glowing ball of hot gases.  It is a kind of gigantic atomic furnace in which the temperature at the center may be as high as several million degrees.  Hydrogen and helium are the most common gases found in a star.  Although they are made up of gases, their centers are so dense and hot that the atoms of gas are constantly colliding and fusing together into new materials.
As the atoms unite, some of their atomic energy is given off  in the form of heat and light which stream away from the star in all directions.  This is why stars shine.  Scientists can find out all this by using instruments called spectroscopes.  With these instruments they can tell from the light a star gives what the star is made of and how hot it is. – Dick Rogers

Sunday, September 6, 2015

How did death valley get its name?

Death Valley
Death valley was named in 1849 but the survivors of a party of prospectors, many of whom died of heat and thirst while looking for gold in the valley.  The hottest, driest and lowest place in the United States is Death Valley.  Death Valley is a desert basin that lies mostly in Southern California.
Death Valley is about 140 miles long and 4 to 16 miles wide.  About 500 square miles of the valley are below sea level, including the lowest spot in North America (282 feet below sea lever near Bad Water).

Only about two inches of rain fall on Death Valley’s wastelands each year and the scorching heat has reached 134 degree in the shade—a record high temperature in the United States.  Despite the burning hear many kinds of plants thrive here, such as mesquite and desert holly.  You can find coyotes, rabbits, rattlesnakes, birds and many other creatures living here, too. – Dick Rogers


Thursday, September 3, 2015

Why Is A Desert Dry?

Deserts cover nearly a fifth of the earth’s surface.  We would probably describe a desert as a hot, barren land where it hardly ever rains—a land so dry that few plants can grow on it, and where other
Dry Desert
forms of life also find it difficult to exits.  The desert we have just described occupies nearly a fifth of the earth’s land surface.  Large deserts can be found in all of the continents except Europe.
The driest and hottest deserts are found in the trade wind zones north and south of the Equator.  Deserts in these areas, such as the Sahara Desert of North Africa, are dry even though they may be near the ocean waters.  Here the winds blow across the desert toward the Equator and become very hot and dry, and release little of their moisture as rain.
Some deserts are dry because they are so far from the sea that the winds blowing in from the ocean lose their moisture long before they reach these deserts.  And in many cases, desert regions are cut off from the moisture laden sea air by tall mountains that catch the rainfall on their seaward side. – Dick Rogers