STARS IN THE SKY NEBULAE BIRTHPLACE, NIGHT SKY STARS, STARS IN SPACE, STARS IN THE SKY,

                              stars in the sky

                           

   

 Stars, which are balls of gas (mostly the gases hydrogen and helium), emit radiation. They create energy by fusing hydrogen and turning it into helium in their cores. We see the resulting energy as starlight. Astronomers classify stars based on their size, temperature, color, and luminosity. Size  in this case relates to mass rather than linear measurement, such as diameter. Stars start the same way,but their lives play out according  to their size and mass. The mass of a str determines all of its other characteristics,including how hot it is,what color it is, and how long it will live. Massive stars are hot and blue, whereas small stars are cool and red.

      

    IN STARS, SIZE MATTERS   

Small stars continue to burn for hundreds of billions of years. The largest stars, about a hundred times the mass of the sun, live shorter lives burning out after a few millions years and dying with a bang. They become exploding supernova that may leave behind a remnant of glowing gas. Shock waves  from supernova tend to compress interstellar gas, which may ignite and become a new star:stellar recycling.
  Facts  light years:the distance traveled by light moving in a vacuum in the course of one year, at its accepted velocity of 186,282 miles per seconds;used as a unit to describe distance between objects in the universe./ Neutron star: A body of densely packed neutrons, formed after explosion of a supernova./ Supernova; The violent, luminous explosion at the end of a massive star's life.

NEBULAE: BIRTHPLACE OF STARS

            Stars are born in an enormous cloud  of interstellar dust and hydrogen gas called a nebula.Nebulae represent the building blocks for stars, galaxies, and planets in the universe.Emission nebulae are hot, discrete clouds of primarily ionized hydrogen that glow with their own light. Reflection nebulae emit a bluish glow by reflecting the scattered light of nearby stars.

Absorption on nebulae, or dark nebulae, comprise dense clouds of gas and dust. They appear as silhouettes against the light of brighter object. Nebulae form when stars die. When the end comes for our sun, for example , its outer layers will heat,swell, and eventually blow off.The hot, dead core will create a glowing nebula, which will in turn become a nursery for new stars.

THE DEATH OF NEARBY STARS: triggered the birth of our planet and other content of our galaxy The arms of spiral galaxy such as ours are rich in stellar debris (upper left), cooled clouds of gas and dust out of which new generations of stars are born. Different physical phenomena result in (top to bottom) brown dwarfs ,white dwarfs, neutron stars, and black holes

  

                                                         STARS RANGE IN SIZE

 Star range in size from a white dwarf (bottom) to an O star(top)-both tiny compared with a red giant such as the one filling the lower right-hand corner. Our sun is a Gstar, fourth from the bottom

         

BRIGHTEST STARS 

                            1.SIRIUS,THE DOG STAR 

                                  Blue-white dwarf in constellation Canis major

                             2.CANOPUS

                               Yellow- white supergiant in constellation Carina  

                             

                             3.ALPHA CENTURI

                               Triple star in constellation  centauris

                             4.ARCTURUS

                              Oranged- colored giant in constellation Bootes

                              5.VEGA

                                  Blue dwarf in constellation Lyra

                                6.CAPELLA

                                   Four- star cluster in constellation Auriga