Origin of the Universe & Solar System PDF

# EARTH & LIFE SCIENCE HAND-OUTS ## ORIGIN OF THE UNIVERSE ### The Big Bang Theory The Big Bang Theory states that the universe is expanding and as it continues to expand it becomes less dense. Despite having "bang" in its title, this theory does not support the idea of explosion as the origin of t...

# EARTH & LIFE SCIENCE HAND-OUTS ## ORIGIN OF THE UNIVERSE ### The Big Bang Theory The Big Bang Theory states that the universe is expanding and as it continues to expand it becomes less dense. Despite having "bang" in its title, this theory does not support the idea of explosion as the origin of the universe. This theory is supported by important observations such as expansion of the universe, Big Bang nucleosynthesis, and cosmic wave background. ### Contributors to the Understanding of the Origin of the Universe | Name | Contribution | | ---------------- | ----------------------------------------------------------------------------------------------------- | | Georges Lemaitre | He hypothesized that the universe came from a cosmic egg or the primeval atoms, which is like a giant atom, with all the mass of the universe. His idea was that the myriads of galaxies of stars in the universe formed out of and expanded out from that initial state of the cosmic egg. Primeval atoms represent a concept called "Singularity", which simply means that our universe was in a very hot and dense state and expanded rapidly and as it cooled down due to its expansion, energy was converted to subatomic particles, namely, the protons, neutrons and electrons to make up the atom. | | Edwin Hubble | * "We are not alone." - He recognized that there is a universe of galaxies located beyond the boundaries of our milky way. * "We are expanding." - Hubble published his observation about the light of distant galaxies, that the farthest galaxies are moving away faster than the closest one. | | Arno Penzias | Observed the expansion of the universe through the phenomenon called Cosmic Microwave Background. | | Robert Wilson | * CMB is an invisible, electromagnetic radiation that fills the universe and can be detected in every direction. * CMB is considered to be the oldest light in the early universe. | ### Timeline of the Big Bang Theory * **10^38 – 10^10 seconds: Electroweak ERA** * Elementary particles were forming and electromagnetic and weak forces became distinct. * **10^10 – 0.001 seconds: Particle ERA** * Characterized by the existence of both matter and antimatter. * **3 min: Nucleosynthesis ERA** * Protons, electrons, neutrons dominated and anti matter became rare. * **3 min – 500k yrs: Nuclei ERA** * The universe was said to be composed only of hydrogen and helium, which lasted about 500 000 yrs. * **500k yrs – 1 billion yrs: Atoms ERA** * Atoms were formed and photons were released, forming the microwave background. * **After 1 billion years to present: Galaxies ERA** * After 1 billion years since the big bang, the first galaxy was formed. # ORIGIN OF THE SOLAR SYSTEM ## Solar Nebula Theory The Solar Nebula Theory was first proposed by Immanuel Kant and Pierre Simon Laplace. According to this theory, the formation of the solar system is characterized by several stages. ### Stages of the Solar Nebula Theory 1. **Collapse** * According to the nebular hypothesis, the formation of the solar system started when a great cloud of gas and dust which is called a nebula began to collapse. * The nebula collapses due to the gravitational interaction of particles; it is also triggered by a shockwave from a nearby star undergoing a supernova (powerful explosion). 2. **Flattening** * As it rotated, the solar nebula flattened out and the central region formed a bulge and became hotter. * From the collapse, pockets of dust and gas began to collect into denser regions. * Most materials ended up in a ball at the center while the rest of the matter flattened out into a disk that circled around it. * The ball at the center formed the protosun. 3. **Formation of Protosun** * Protosun is defined as the early stage of the sun's formation which is due to the increase in temperature generated enough to trigger a nuclear fusion and this fusion marked the birth of our sun. * Eventually, the increase in temperature generated enough energy to trigger a nuclear fusion and this fusion marked the birth of our sun. * 99.85% of all the mass in the solar system is in the sun. 4. **Accretion** * Accretion happens when small grains collide and stick to one another until they are massive enough to attract particles. * **Planetesimal:** Particles of dust, rock, and other materials. Small; can be several m to a few km * **Protoplanets:** Celestial objects that are massive enough to accrete more materials * **Planets** ## Planets There are two groups of planets in our solar system. These two groups are terrestrial planets and jovian planets. ### Terrestrial Planets * **Gasses condense into rocky particles:** These clumps accrete more. * **Rocky particles:** Begin to clump. * **Clumps:** Form planetesimals. * **Planetesimals:** Accrete more. * **Terrestrial planets:** Formed (Mercury, Venus, Earth, Mars) ### Jovian Planets * **Gasses condense into icy particles:** These clumps accrete more. * **Icy particles:** Begin to clump. * **Clumps:** Form planetesimals. * **Planetesimals:** Accrete more. * **Jovian planets:** Formed (Jupiter, Saturn, Uranus, Neptune) ## The Sun The sun is a huge ball of glowing gases which is composed of Hydrogen (72%) and Helium (28%). This is also the source of power in the solar system. The sun's gravity holds the solar system together. Without the sun, the celestial bodies would just float on outer space or simply, there would be no planets at all. * **Core:** * Innermost layer where the sun draws its energy. * Consists of Plasma. * Where nuclear fusion of Hydrogen and Helium occurs. * **Radiative Zone:** * This is where the energy produced by the sun travels or radiates. * **Convective Zone:** * Where energy waves pass through via convection currents. * **Photosphere:** * Visible surface of the sun. * Radiation is seen on Earth as sunlight when it reaches Earth about 8 minutes after it leaves the sun. * **Chromosphere:** * Where thin gases rise to the surface of the sun. * Where solar prominences and solar flares occur. * **Corona:** * Outer portion of the sun's atmosphere. * Extends millions of miles in space. * Also known as the sun's halo. ## Planetary Motions Planets move around the sun in its own definite path called an orbit. The Earth rotates on its axis which causes us to experience day and night. On the other hand, when the Earth completes its revolution, it will result in 365 days or 1 whole year. While for the seasons, we experience it not because of rotation or revolution but due to the tilt of the Earth on its axis which is around 23.5 degrees. The tilt of the Earth means that the Earth will lean towards the Sun giving us summer and lean away from the Sun giving us winter. ## Kepler's Laws of Planetary Motion 1. **The Law of Ellipses:** The path of the planets about the sun elliptical in shape, with the center of the sun being located at one focus. 2. **The Law of Equal Areas:** An imaginary line drawn from the center of the sun to the center of the planet will sweep out equal areas in equal intervals of time. * **Perihelion:** The point in the orbit of a planet, asteroid, or comet at which it is closest to the sun. * **Aphelion:** The point in the orbit of a planet, asteroid, or comet at which it is furthest from the sun. 3. **The Law of Harmonies:** The planet's orbital period is proportional to the size of its orbit (semi-major axis). This means that how long a planet takes to go around the sun is related to the planet's mean distance from the Sun. ## Asteroids Asteroids are rocky worlds revolving around the sun that are too small to be called planets. * They are also known as planetoids or minor planets. * There are millions of asteroids, ranging in size from hundreds of miles to several feet across. * Nearly all asteroids irregularly shaped; however, a few of the largest are nearly spherical. * Found in an area called the asteroid belt which is in between Mars and Jupiter. ## Comets Comets are icy bodies in space that release gas or dust. * They are often compared to dirty snowballs. * Some researchers think comets might have originally brought some of the water and organic molecules to Earth that now make up life here. * Comets orbit the sun, but most are believed to inhabit an area known as the Oort cloud, far beyond the orbit of Pluto. ## Meteor, Meteoroids, Meteorites * **Meteor:** A small particle from a comet or asteroid orbiting the sun. * Also known as a shooting star * **The flash of light that we see in the night sky (not the debris itself); when meteoroids enter Earth's atmosphere** * **Meteoroids:** * **Refers to the material (debris) itself as it hurtles through space** * Chunks of rock and metal falling through Earth's atmosphere and heated to incandescence by friction * **Meteorites:** * **When a meteoroid survives the fall through the atmosphere and lands on Earth**