EL SCI 1

• Baryonic matter


  Ordinary matter consisting of protons, electrons, and neutrons that comprises atoms, planets, stars, galaxies, and other bodies
• Dark matter


  Matter that has gravity but does not emit light
• Dark Energy


  A source of anti-gravity; a force that counteracts gravity and causes the universe to expand
• Protostar


  An early stage in the formation of a star resulting from the gravitational collapse of gases
• Thermonuclear reaction


  A nuclear fusion reaction responsible for the energy produced by stars
• Main Sequence Stars


  Stars that fuse hydrogen atoms to form helium atoms in their cores; outward pressure resulting from nuclear fusion is balanced by gravitational forces
• Light years


  The distance light can travel in a year; a unit of length used to measure astronomical distance
• The Universe is at least 13.8 billion of years old and the Earth/Solar System at least 4.5-4.6 billions of years old
• If spending 1 billion pesos at 1 peso per second

  It would take 32 years
• The Earth is part of the solar system, which is at the outer limb of the Milky Way Galaxy
• The universe comprises all space and time, and all matter and energy in it
• Composition of the universe

  • 4.6% baryonic matter
  • 24% cold dark matter
  • 71.4% dark energy
• Hydrogen, helium, and lithium are the three most abundant elements in the universe
• Birth, evolution, death, and rebirth of stars

  1. Gravitational collapse of gas clouds

  2. Transformation into protostar

  3. Thermonuclear reactions in stellar interiors

  4. Hydrogen fusion to helium in main sequence stars
• The universe is 13.8 billion years old, with a diameter of at least 91 billion light-years and a density of 4.5 x 10-31 g/cm³
• Redshift


  Shift of spectral lines toward the red part of the electromagnetic spectrum, indicating that a star or galaxy is moving away from the observer
• Redshift is evidence for an expanding universe, as predicted by Einstein's Theory of General Relativity
• The cosmic microwave background (CMB) radiation is a pervasive, uniform glow in the microwave band coming from all directions, with an average temperature of about 2.7 degrees above absolute zero
• The discovery of the CMB radiation earned Arno Penzias and Robert Woodrow Wilson the Nobel Prize in Physics in 1978
• The Big Bang Theory postulates that 13.8 billion years ago, the universe expanded from a tiny, dense and hot mass to its present size and much cooler state
• Big Bang Theory


  The currently accepted theory of the origin and evolution of the universe, based on General Relativity and the Cosmological Principle
• The "bang" in the Big Bang Theory should not be taken as an explosion, but rather the simultaneous appearance of space everywhere