Earth and Space Science: The Study of the Universe

Earth and Space Science: The Study of the Universe

1. Star

   • A hot ball of plasma, and electrically charged gas, that shines because nuclear fusions is taking place at its core
     • Nebula
       • Cloud of gas and dust in which stars are developed.
     • Supernova
       • Explosion of a star, collasped core, which is caused by the gradual build-up of heavy elements in the star's centre
     • Nuclear Fusion
       • The process in which the nuclei of atoms fuse together to form larger atoms which releases an enormous amount of energy
     • Solar system
       • The Sun together with all the planets and celestial objects held by the Sun's gravitational attraction
         • An astronomical unit(AU) equals the average distance between the Earth and the Sun
         • At a distance of 3AU from the Sun, there is a region of rocky debris called the asteroid belt consisting of pieces of rocks.

2. Properties of Galaxies

   • Black Hole
     • A region of space in the center of each galaxy where gravity is so strong that not even light can escape. It pulls a star in and destroys it, adding to its mass
   • Dark Matter
     • Matter that is invisible because it does not interact with light or any kind of radiation and has strong gravitational pull that keeps our universe together
   • Star Clusters
     • Open Cluster
       • Contains a few hundred to a few thousand stars which are the youngest stars in the universe
     • Globular Cluster
       • Contains hundreds of thousands of the oldest stars drawn together by the stars' gravity

3. Galaxy Shapes

   • Spiral
     • Spiral-shaped arms that radiate out from the galaxy's center and looks like a thin disk from the side. New arms are formed continually as older ones disappear or lose shape and make a full rotation every 300 million years.
   • Barred
     • About half of spiral galaxies have a bar across them which give them the name barred spiral.
   • Elliptical
     • Spherical, foot-ball shaped or cylindrical and extremely old stars resulted from merged galaxies.
   • Irregular
     • Distorted and nether spiral nor elliptical, resulted from collisions of galaxies and stars were drawn away

4. Big Bang Theory

   • There are many other galaxies beyond the Milky Way
   • Galaxies are constantly moving apart and the universe is expanding
     • Spectral Lines
       • Created as each gas that makes up a star absorbs some of the light energy. Each element has its specific pattern of spectral lines.
     • Spectral Shifting
       • Change in position of spectral lines to the left or right
         • Approaching star- blue(left) shift, short and compressed
         • Moving away star- red(right) shift, long and stretched out