1. Formation of Solar System
Chapter 27
Planets of the Solar System
Austin HS – Earth and Space 2016

2. Formation of the Solar System
The solar system consists of the sun and all of the planets and other bodies that revolve around the sun
Planets are any of the primary bodies that orbit the sun
In the 1600s and 1700s, it was thought that the sun formed first and threw off the materials that later formed the planets
In1796, Pierre-Simon de Laplace, advanced a hypothesis that is now known as the nebular hypothesis

3. The Nebular Hypothesis
Laplace’s hypothesis states that the sun and planets condensed at about the same time our of a rotating cloud of gas and dust.
Matter gathered into cloud of dust and gas, the amount of gravity near one of these cloud increased as a result of a nearby supernova or other forces
The rotating cloud of dust and gas from which the sun and planets formed is called a solar nebula.
Energy from collision and pressure from gravity caused the center of the solar nebula to become hotter and denser.
When temp. became high enough- hydrogen fusion began
A star called the sun formed
The sun is composed of about 99% of all the matter that was contained in the solar nebula

4. Formation of Planets
While sun formed in the center of the solar nebula, planets forming in the outer region
Planetesimals, are the small bodies from which a planet originated in the early stages of formation of the solar system
Planetesimals joined together through collision and force of gravity to form large bodies called protoplanets
Protoplanet’s gravity attracted other planetesimals in the solar nebula, eventually they became very large and condensed
The formed planets and moons
Moons are smaller bodies that orbit the planets

5. Formation of the Inner Planets
Features of a newly formed planet depends on the distance between protoplanet and developing sun
Protoplanets closet to the sun (Mercury, Venus, Earth, Mars) contained large % of heavy elements such as iron (Fe) and Nickel (Ni)
they lost less dense gases because at the temp of the gases, gravity was not strong enough to hold
Lighter elements may have been blown away or boiled away by radiation
The denser material sank to the center, layers formed
Inner planets have solid surfaces similar to earth, they are smaller rockier, and denser then outer planets

6. Formation of the Outer Planets
The next 4 planets (Jupiter, Saturn, Uranus, Neptune) are very different from inner planets
Outer planets formed in the colder regions of the solar nebula far from the sun
Thus they did not lose their lighter elements such as helium and hydrogen/ or their ices (water ice, methane ice, ammonia ice)
@ 1st thick layers of ice surrounded small heavy elements, due to heat and pressure in planets interior, ice melted to form layers of liquid and gases
Planets are referred to as gas giants because they are composed mostly of gases, have low density, and are huge planets
Jupiter’s density is only 24% of that of earth’s density.
Jupiter has a diameter 11 times larger than Earth’s diameter.

7. The Different Planet - Pluto
Pluto farthest planet from the sun
Pluto is very small unlike other outer planets
Pluto is very cold, may be described as an ice ball that is made of frozen gases and rock
Astronomers have also discovered hundreds of objects that are similar to Pluto and that exist beyond Neptune’s orbit
None are larger than Pluto
Many scientist think that Pluto does not qualify as a major planet

8. Work on The Nebular Model of the Formation of the solar system.
The End
Work on The Nebular Model of the Formation of the solar system.