• The Solar System began 5 bil yrs. Ago
• The Nebular Theory states that the solar syst. Began from a nebula that was the remains of a supernova
• The cloud of gas and dust condensed into clumps of elements that eventually made the sun and the 9 planets
• The sun was made up of most of the H and He found in the cloud
• Everything in the solar system is made from the elements released from a supernova
• These elements rained on the nebula causing the cloud to collapse and condense into the Sun and planets
• The cloud collapsed into a flat spinning disk that eventually made the solar syst.
• This disk was 10 bil. Km across
• The collapse of the gas created nuclear fusion, causing the sun to heat the solar syst.

• The clumps of matter in the flat disk came together to eventually make the planets
• Solid elements came together to make the Terrestrial planets
• The H and He near the Sun were burned away from Terrestrial Planets

SFormation of the Solar System

• Pluto: its believed that Pluto was one of Neptune’s moons and it broke away from Neptune’s gravitational pull
• Asteroids formed between Mars and Jupiter and Jupiter and Saturn
• Comets formed at edge of S. Syst

• Ptolemy: Stated that Earth was the center of the Universe
• Also stated that all objects orbit the Earth
• Stated that the Universe was perfect, unchangeable, divine
• Was the accepted theory for 1400 yrs.

• In 1500’s Copernicus stated that the Earth and other objects orbited the Sun
• Also stated that all these objects orbit in one direction
• Each planet took a different amt. Of time to orbit the Sun
• Copernicus’ theory was wrong b/c it stated orbits were round

• Supported that planets orbited Sun
• Each planet orbits in an Ellipse
• Each planet orbits in a counterclockwise direction
• Planets closest to Sun have a smaller orbit then ones far away

• According to Newton, a planet’s motion around the Sun is due to Inertia and Gravity
• Inertia keeps the planet moving in one direction
• Gravity keeps the planets from drifting away

• Period is time it takes a planet to revolve around the sun
• Ex: Mercury has a period of 88 days
• Ex: Earth has a period of 365.25 days

• Period of rotation is the time it takes for a planet to spin on its axis
• ex: Mercury day = 59 Earth days
• ex: Earth day = 24 hrs
• ex: Jupiter day = 9.8 hrs
• ex: Pluto day = 6 Earth days

• Named for the god of speed, or messenger god.
• Has a period of 88 days
• Has a day of 59 days (Earth)
• Distance: 36mil mi. (58 mil km)
• Diameter: 3031mi. (4880 km)
• Number of moons = 0
• Daytime temp: 620F, 427C
• Nighttime temp: -320F, 170C
• Atmosphere: trace amts. Of H, He, Na
• surface is covered with craters
• Surface is covered with Scarps (cliffs) and wrinkles due to the constant heating and cooling of the planet
• No spacecraft has landed Mercury
• Mariner 10 did a fly by in 1975
• No weather due to trace atmos.

• Named after the god of love
• Is the second brightest object in the night sky
• Is located 67mil mi. from the sun (108 mil km)
• has a diameter of 7251 mi. (12, 104km)

• Its period is 225 days
• Its day is 243 days (yes day is longer than the year)
• It rotates backwards
• Number of moons = 0
• Its atmosphere is 96% CO₂ and 4% Sulfuric Acid
• The surface is covered in Sulfur

• Average Temp is 900F (480 -33C)
• Because of the high level of CO_2. Venus suffers from an excessive greenhouse effect
• Air pressure is 100x stronger than Earth.
• Venus shows evidence of oceans, sea beds and a coast

• Is hard to see surface due to thick atmosphere
• American Spacecraft to go to Venus:
• Pioneer
• Venus orbiter
• Magellan- Used radar to map surface

• Venera- Soviet spacecraft to actually land on surface. Took 2 photos before being destroyed
• Highest Mountain Montes Maxwell (20% higher than himalayas)

• Has a valley 9500 ft below surface
• surface contains many plains and continents as well as volcanoes that are plateau shaped