Origin of the Universe and Solar System

• The formation of stars and galaxies only started 300 to 500 million years after the big bang.
• Our solar system formed about 4.571 billion years ago from a dense cloud of interstellar gas and dust.
• Encounter Hypothesis 


  States that the sun encountered a rogue star. Upon the encounter, hot gas was removed from both stars due to their gravitational interaction
• The hot gas then accumulated and formed the planets. The material from less dense rogue star formed the outer planets, while that from the sun formed the inner planets.
• Protoplanet Hypothesis 


  Suggests that a cloud of gas and dust, about 10 million kilometers in diameter, rotated slowly. Due to its own gravity, the cloud of gas and dust began to collapse.
• The compression made the interior of the cloud hot, resulting to a hydrogen fusion which formed sun. Surrounding the sun was a great plate-like disk containing a huge whirlpool (eddies) where matter accumulated due to friction forming protoplanets that later became planets and moons.
• Nebular Hypothesis 


  It was the most favored model that was first proposed by Immanuel Kant and Pierre Simon Laplace. This states that the Solar System was formed from a slowly-rotating cloud of gas or nebula that collapsed and flattened.
• Its hot central region became the sun, and its surrounding materials became the planets and other objects. However, according to calculations, the solar nebula would not be able to form the rings nor the planets.
• Solar Nebula Theory


  This theory combined the idea of a flattening solar nebula with that of a condensing interstellar dust as the nebula cooled, which serves as a condensation nuclei where matter accumulated.
• Creationism 


  The belief that the universe and the various forms of life were created by God out of nothing.
• Evolutionary Theory


  A scientific theory that explains the diversity of life without invoking the concept of God or any divine power.
• Steady State Theory


  A theory stating that the counting of galaxies in the Universe remains constant, with new galaxies continuously forming to fill the spaces left by those that have moved beyond the observable Universe.
• Sir Hermann Bondi, Thomas Gold, and Sir Fred Hoyle


  The scientists who first proposed the Steady State Theory in 1948.
• Bigbang hypothesis 


  The alternative cosmological theory that the Steady State Theory was proposed in response to.
• Richard Tolman


  The scientist who proposed the Oscillating Universe Theory or Pulsating Theory.
• Pulsating Theory


  A cosmological theory suggesting continuous expansion and contraction of the universe.
• Georges Lemaitre

  In 1927, who was the Belgian cosmologist and priest who first deduced the idea of the Big Bang based on Einstein's General Theory of Relativity?
• Bigbang Theory

  The event about 13.7 billion years ago when time, space, matter, and energy came into existence. Initially, all matter of the universe was present at a single place in the form of a hot and dense fireball with a temperature of nearly 10^12K. After approximately 20 billion years, an enormous explosion occurred, scattering the matter in all directions, which later formed galaxies and stars.
• Edwin Hubble

  Whose discovery of galaxies moving away from each other at high speeds did Lemaître use to support his theory?
• Dr. Gamow

  Who, along with his student, published a paper in the late 1940s explaining how the current levels of hydrogen and helium in the universe support the Big Bang theory?
• Cosmic Microwave Background Radiation

  Arno Penzias and Robert Wilson
• Big Bang


  The most popular theory of our Universe's origin, centered on a cosmic cataclysm where the entire observable universe was compressed into a hot, dense mass before rapidly expanding
• The Big Bang theory was born of the observation that other galaxies are moving away from our own at great speed, in all directions
• Before the Big Bang, the entire observable universe was compressed into a hot, dense mass just a few millimeters across
• The Big Bang theory suggests the universe expanded with incomprehensible speed from its pebble-size origin to astronomical scope in the first instant after the Big Bang
• The Big Bang theory maintains that expansion has continued, but much more slowly, over the ensuing billions of years
• Cosmic microwave background radiation


  A tangible remnant of leftover light from the Big Bang, found throughout the universe
• The Big Bang Theory leaves several major questions unanswered, including the original cause of the Big Bang itself
• Gravitational waves


  Waves that squeeze and stretch space, produced during the inflationary expansion of the universe
• The BICEP2 experiment provided the first direct evidence that gravitational waves rippled through the infant universe during inflation
• The BICEP2 experiment used novel superconducting detectors to detect the extremely faint B-mode polarization signal, providing the strongest support yet for cosmic inflation

  
• Nebular Hypothesis


  The theory that the solar system developed from the condensation of an enormously dispersed gaseous atmosphere surrounding the sun

  
• Planetesimal Theory


  The theory that the planetary system was formed from materials removed from the sun by tidal action caused by a passing star

  
• Dust Cloud Theory


  The theory that the nebula was mainly composed of hydrogen and helium, with only 1% of heavier elements, and interactions of the gas molecules produced swirls that formed planets and satellites

  
• Protoplanet Hypothesis


  The theory that the original nebula was so massive that on further contraction and flattening, it broke into separate clouds or protoplanets that remained stable in the tidal field of the sun
• The solar system where the Earth belongs is just a small part of the vastness that we call the universe, and its origin is still not fully understood
• Ultraviolet radiations drove away into space remnants of the nebula and the large atmosphere of the planets, which thus looked like a swarm of comets with tails

  
• This hypothesis proposed a process that could have developed planetary systems around many stars
• The majority of yellow stars, like the sun, may possess systems of planets
• The solar system where the earth belongs is just a small part of the vastness that we call the universe