Origins and Formation of the Solar System 312-1 Describe theories on the formation of the solar system
Smash, crash and bang The solar system is big, and big things have big origins
A history of ideas The solar system wasn t always seen in the way we think of it today. In order to develop a theory on how the Solar System formed, we needed to accept the idea of HELIOCENTRISM Heliocentrism the SUN is the CENTER of the solar system and all planets and objects orbit around it.
vs. GEOCENTRISM the former belief that the EARTH was the center of the solar system, even the Universe. This view was held as truth by popular culture and religious authority for over 100 years. Now enter the movers and the changers: Copernicus Kepler Galilei
Challenging the popular model: The combined observations and written arguments of these three men eventually changed the world view that the SUN is the center of the solar system and not the Earth. This was difficult to do at that time. Because the Church held that the geocentric model was true, many would not speak against the church in fear of consequences against them. We have only really accepted the Heliocentric model for about 500 years! Youtube - Galileo's Sun Centered System
FAST FOWARD: Today our understanding of the origin of the Solar System is called the: NEBULAR HYPOTHESIS or SOLAR NEBULAR DISK MODEL
In a nut shell: 4.5 to 6 billion years ago 1. Giant cloud of gas (a NEBULA or GIANT MOLECULAR CLOUD) collapses due to the UNSTABLE gravity of particles at its center. 2. Gases (Hydrogen, Helium) at the center of this collapse formed the SUN. 3. Other materials formed a spinning PROTOPLANETARY DISC around the new born sun. 4. From this DISC, the planets formed by the smashing of materials into one another (a process called ACCRETION)
NEBULA
Protoplanetary disc
Accretion of mater in the protoplanetary disc
Accretion continued: The larger the ball of material grows, the more gravity it exerts on stuff around it, the more stuff will be attracted to it, making it even bigger! Protoplanetary disc with the accretion of materials occuring
Formation of the planets. -First to form were PLANETESIMALS, smaller round bodies of material. Planetesimals then became PROTOPLANETS. These bodies then eventually settled into stable orbits around the Sun and developed their atmospheres. UnivColorado animation of accretion
Gas giants, the snow line and Iron The planets of the solar system are grouped into the inner TERRESTRIAL planets and the outer - JOVIAN and ICY- Inner -Terrestrial Mercury Venus Earth Mars These are composed mostly of rock and metals planets or GAS GIANTS. Outer - Jovian and Icy Jupiter Saturn Uranus Neptune These are composed of mostly ice and frozen gases.
Why are planets close to the sun made of rock and those far away made of ice Its all about 1. temperature and 2. wind 1) TEMPERATURE : Closer to the new sun it was too hot for gas and water to condense into solids, only metals like iron and rock could be solid at such high temperatures. and frozen gases? 2) Solar WINDS the ignition of the Sun created a blast that pushed the lighter gases outwards to the edges, where it was cool enough for them to condense and form solids.
SNOW LINE This is at a certain distance from the Sun, where temperatures are cold enough for water and other gases to freeze and condense to form the icy planets. Astronomers believe snow lines in other solar systems are VITAL to planet formation because frozen water and help dust particles stick together and so help ACCRETION. Snow lines have been observed in other solar systems. This direct observation helps support the current theory on how the solar system formed.
Click here! Youtube Stephen Hawking and awesome graphics
Differing theories The Solar Nebula Hypothesis is not the only one that tries to explain the formation of the Universe but has currently been accepted as the best. There are many others that include ideas about where the original dust particles came from and why they began to stick together.