The Stars

One Night some years ago , people in middle Atlantic States turned in to a radio program . What they heard was imaginary and meant to be entertaining . Actually , it frightened many of them out of a night's sleep. Some fled in panic from the cities toward Canada . Others  got whatever weapons they could to defend their homes . The cause of this wild panic was a vivid description on the radio program of a imaginary attack on the New Jersey region by men from Mars .

Once Upon A time :-

                                The people of ancient civilization spent a good deal of time wondering about the different objects in the sky . A teacher named Aristarchus of Samos , an island in the Aegean Sea , said that the earth revolves around the sun . Aristarchus lived between 310 and 250 B.C. 

 1) Stars and Suns :

                                                   The astronomer of ancient times knew nothing of the real nature of stars . to him they were simply mysterious ornaments in the sky  dome . The astronomers of today knows that the stars are brilliant fiery suns similar to our own sun but they  very much farther away . If our sun were far enough from us , it would look like a star . On the other hand , if any of the stars were close enough to us , they look like a Suns .

2) Seeing Stars :

                              The darker the surrounding the easier it is to see the stars . The starry sky looks brightest on a night when there is no moon and from a position where no street lights or other artificial light can blur the light of the stars . Stars are in the sky by days as well as by night , but the brilliant light of the sun completly outshines their far fainter light , making the stars quite invisible . 

3) How many Stars ?

                                  While the brilliance of the sky on a clear moonless night shows an infinite number of star-by-star count reveals about 5000 stars actually visible to the naked eyes in the heavens of both the Northern and Southern Hemispheres . only about 2000 of these stars can be seen by an observer at any one time . But with aid of modern times , millions of stars can be seen , while more millions of stars can be seen , while more millions of still fainter stars can be shown by photographic plates that are much more sensitive than the human eyes . 

4) The Telescope :

                                           The telescope is an instrument whose lens or mirror , much larger than the lens of the human eye , can gather together a much greater quantity of light from a star and focus it in one spot , it sees hundreds or thousands of times as much light from the stars as it can see " Naked " or without the telescope . Stars already visible look much brighter -not larger -and  millions of stars that are visible through the telescope . Sensitive  Photographic plates , placed at the focus of the telescope's light and exposed for many hours , show large numbers of stars that the eye , even through the telescope , is unable to preceive . 

The great 36-inch Refracting telescope of the University of California's Lick observatory at Mount Hamilton , California .

    A Telescope that uses lenses to focus straight is called Refracting Telescope or Refractor  . The World's largest refractors are those of the Yerkes Observatory at William Bay in Wisconsin , and the Lick observatory at Mount Hamilton in California .The Yerkes lens is 40 inches in Diameter ; the Lick lens 36 inches in it's diameter .

Yerkes Observatory , Geneva

A telescope that uses a curved mirror  to focus the starlight is called a Reflecting Telescope or Reflector . The word's largest reflectors are the telescopes at the Mount Palomar and Mount Wilson ,both in  California . The Palomar mirror is 200 inches , or almost 17 feet , in diameter  ! The Mount Wilson mirror is 100 inches in diameter .

Mount Wilson Observatory

As from above we can only imagined that the Telescope of above  observatory is How Big it ? For we can imagine as saw the image as it above show .....!!!!!!                          

 5) What Stars are made of :

                                                The Chemical composition of a star  can be determined by the Spectroscope . Stars like the sun , are made of Chemical elements so hot that all of them  are in the form of  glowing gas vapor . The Spectroscope  is an instrument  which analyzes the light given off by incandescent (glowing hot) material so that the scientist can tell which elements they contain .Thus far 66 & 92 natural elements have been identified in our sun ,and the other stars appear to be made of the same elements .

6) How  large is a Star  ?

                                         There is a tremendous  range in the sizes of stars , known as Dwarfs ,  have diameters of about 10,000 miles , making them only a little larger than the earth .The Largest star known as Giants , have  diameters upto 2,000,000,000 ( 2 billions ) miles !  . Our sun ,an average -sized 

Star , has a diameter of 864,000 miles a distance almost equal to four trips from the earth to the moon .

Antares and Betelgeuse ,two of the bright stars of our Whole Sky ,are classed among the giants , with the diameters hundreds of times as a Large as the sun's .

Our Daytime Star :

                                  We may guessed by now that just as the earth is not only planet in the sky , so our sun is not the only sun in the space . Actually each star is a sun , & our sun is a medium - sized star as star go . Even so , our sun is more than a hundred times  larger in diameter than the earth . The sun's diameter is approximately 864,000 miles . it would require more than a million earths to equal the volume of he sun .

                                 The earth's distance from the sun varies from 91,500,000 miles in January to 94,500,000 miles in July  but the figure usually mentioned is the average distance of  93,000,000 miles .

                             Until the 17th century , the sun was regarded by everyone as a uniform , fiery ball , but 1610 Galileo discovered spots on it's surface .Further observations revealed that these sunspots were moving across the sun's surface at the different speeds . Later , scientist discovered that the sun is gaseous and not solid  and that the sun rotates or spin's . Although the sun is a globe of glowing gas , it is known as weigh 1.4 times as much as an equal volume of water .No one could come within 50,000,000 miles of it without burning up .The surface temperature  of the sun is about 10,000 ℉ . and its internal temperature is estimated at about 68,000,000 ℉ . Only a tiny fraction of the heat radiated  from the sun is received by each of the planets . The Earth gets about one Billionth part of the sun's Radiation .