Chapter 28 Our Solar System Our Solar System

Chapter 28 Our Solar System

Our Solar System • Big Idea: Using the laws of motion and gravitation, astronomers can understand the orbits and the properties of the planets and other objects in the solar system

Our Solar System • • 28. 1 – Formation of the Solar System 28. 2 – The Inner Planets 28. 3 – The Outer Planets 28. 4 – Other Solar System Objects

Our Solar System Quick facts • It is likely that Jupiter was the first planet in the solar system to form • It rains sulfuric acid on Venus • Mercury’s days are two-thirds the length of its years

28. 1 Formation of the Solar System

Formation of the Solar System • Objectives • Explain how the solar system formed • Describe early concepts of the structure of the solar system • Describe how our current knowledge of the solar system developed

Formation Theory • Theories of the origin of the solar system rely on direct observations and data from probes • Scientific theories must explain observed facts • • • Shape of the solar system Differences among the planets Nature of the oldest planetary surfaces Asteroids Meteoroids Comets

Big Bang Theory • No one knows what happened exactly • All the scientists know it that a marble sized universe was produced by a big bang and a large ball of heat started to grow • This ball kept expanding, but it didn’t contain matter it was all energy • Mass and energy are interchangeable • It changed these particles and matter • Short Explanation

Big Bang Theory • There was so much energy, the particles slowed down and created matter • The universe was then expanding • It all cooled, when protons and neutrons cooled • They combined to form Helium an Hydrogen • Video

Collapsing of Interstellar Clouds • Stars and planets form from interstellar clouds • These clouds are made mostly from hydrogen and helium gas with small amounts of other elements and dust • There is a gravitational force between all of these materials which is how it is thought our planets and stars formed

Collapse Accelerates • At first a collapse is slow but it gradually accelerates • It becomes much denser in the center • Eventually, the cloud becomes a rotating disk with a dense concentration of matter at the center

Matter Condenses • Because of this spinning and condensing of Hydrogen and helium scientists believe this is how the sun formed • There is high pressure and high temperature with this matter condensing • Because of this temperature gradient, different elements and compounds condensed at a certain distance away from the sun • This affected the distribution of elements in the forming of planets

As a result • Inner planets are higher and richer in melting point elements and the outer planets are more volatile elements • This also explains why the outer planets consists of gases and ices

Planetesimals • Because of these different particles were now condensing in our solar system, they grew as grains and collided • These colliding particles merged to form planetesimals • Planetesimals are objects hundreds of kilometers in diameter

Gas giants form • The first large planet to form was Jupiter • It grew from merging of icy planetesimals that contain lighter elements • Saturn grew similarly but not as large • Because each gas giant attracted material they all started to form rings and satellites

Terrestrial Planets Form • The terrestrial planets started to form from elements that resisted vaporization from the sun • Scientists also believe the sun swept much of the gas in the area of the inner planets • Thus, the inner planets didn’t develop satellites • Video

Debris • Material that remained after the formation of the planets and satellites is called debris • Eventually this debris diminished as they hit other planets or were diverted out of the solar system • Others formed into asteroids or comets • The asteroid belt formed because of Jupiter’s gravitational force

Kepler’s First Law • The laws are named after a German astronomer named Johannes Kepler (1571– 1630), who proposed them in the early 1600 s. • Kepler was able to summarize the carefully collected data of his mentor—Tycho Brahe—with three statements that described the motion of planets in a sun-centered solar system. • The laws are still considered an accurate description of the motion of any planet and any satellite.

Kepler’s First Law • An ellipse is an oval shape that is centered on two points instead of a single point • These two points are called foci

Kepler’s Second and Third Law • In addition to discovering the shapes of the planetary orbits, a planet does not orbit at a constant distance from the sun • Kepler has also shown that planets move faster when they are closer to the sun • The length of time it takes for a planet to travel a complete orbit around the sun is called its orbital period • Pg. 801 in your text • Video