The Solar System Chapter 8
Section 8-1Planet Motion Gravitational forces formed the solar system and cause the planets to orbit the Sun Objectives: • Compare and contrast geocentric and heliocentric models • Describe each planets position • Classify the planets based on location and characteristics
Models of the Solar System • Early scientists believed that the Earth was the center of the Universe because of their limited knowledge • Hierarchy: Sun/Star, Planets, Solar system, Galaxies, Universe
Geocentric Model • The Earth was considered the center of everything • The Greek Scholar Ptolemy believed that the Earth was surrounded by a series of spheres that contained planets and stars • Planet comes from the Latin word “planasthai” meaning “to wander”
Heliocentric Model • 1543 the Polish astronomer, Nicholas Copernicus proposed a new model “Sun-Centered” • He stated that the moon revolves around the Earth and the Earth around the Sun
Heliocentric Model • In 1625, using a primitive telescope, the Italian astronomer, Galileo Galilei reinforced the ideas of Copernicus • Observed the phases of the planet Venus and the moons of Jupiter • Confirmed that the Sun was the center of the solar system
Understanding the Solar System • In the 1626, the astronomer Johannes Kepler concluded that the planets move around the Sun in an elliptical orbit instead of spherical/circular
Understanding the Solar System • Kepler also discovered that the planets move at different speeds around the Sun, the closer the planet is to the Sun the faster it moves/revolves • One revolution/year on Mercury is 88 days and it takes Neptune 164 years to complete one revolution
Classifying Planets The Planets can be classified in three ways depending upon the information that you are looking to obtain: • Size • Characteristics • Location
Classifying Planets • Characteristics (Terrestrial and Jovian) • Location (Inner Planets and Outer Planets separated by the asteroid belt) • Size (Jupiter to Mercury)
Origin of the Solar System • The latest evidence suggests that our solar system formed with a group of stars 4.6 billion years ago • The force of gravity pulled and condensed a collection of dust and gas “cosmic garbage” together that was probably the result of an exploded star
Origin of the Solar System • As this collection of gas and dust began to condense and spin it took shape. • Temperatures inside the cloud increased allowing the hydrogen in the cloud to fuse into our Sun…and the rest is history!
Origin of the Solar System • Why do we think this? With the improvements in satellite technology we can actually see it happening elsewhere in the galaxy/universe
Other Solar Systems • Remember that our Sun is just one of trillions of stars in our galaxy…it is a very common type of star. • Each star is a sun…not all have planets revolving around them…but we have discovered 200 so far that do.
Section 8-2The Inner Planets Objectives: • Compare and contrast the other inner planets with Earth • Describe the important characteristics for each inner planet • Evaluate the success of various missions to Mars
Planets Near the Sun The planets near the sun are made of solid material/rock “terrestrial” because the pull of the Suns gravity attracted the heavier elements close to it as the solar system formed
Mercury • The smallest and closest planet to the Sun • Mariner 10 passed by from 1974-1975 and photographed 45% of the surface • The core is suspected to be iron based upon the magnetic field surrounding the planet
Mercury’s Surface • Mercury’s core condensed and shark faster that the outer layers resulting in a surface the is covered with high cliffs and mountains
Mercury’s Atmosphere? • Mariner 10 did pick up traces of gas surrounding the planet, but due to the low gravitational pull of the planet the gases are thought the be remnants of solar wind • Temperature varies from 427 C (800 F) to -170 C (-274 F)
Venus • Same size as Earth • Venus has a dense atmosphere that is mostly carbon dioxide • The atmosphere contains sulfuric acid • 2% of the suns light actually hits the planets surface due to thick clouds • Temp is a constant 450 to 475 C (1000 F)
Satellites to Venus • 1970’s Russia/Soviet Union sent the Venera probes that photographed and mapped the surface • In 1995 the United States probe Magellan also mapped the surface in more detail
Earth • Third planet from the Sun with a temperature range that allows water to be in all three states (solid, liquid, and gas) • Meteors tend to burn up in the atmosphere • Ozone layer protects life from harmful solar radiation
Mars • Fourth planet from the Sun • “Red Planet” due to iron oxide “rust” in the surface rock • Tilted 25 on its axis causing seasons • Frozen carbon dioxide and (water?) at the north and south poles • Dust storms as seasons change make the planet appear to change color
Mars Atmosphere • The Martian atmosphere is much thinner that that of the Earth and does not filter out the harmful rays of the Sun • Temperature ranges from 37 C (95 F) to -123 C (-300 F)
Martian Moons • Mars has two heavily cratered moons, Phobos and Deimos. • Phobos is slowly falling toward Mars and will eventually impact (50 million years from now) the surface of Mars
Was Mars Once Covered with Water? • This is still in dispute, the current temperatures do not allow for liquid or gaseous water to exist on the surface • There are indications in the land that look like the result of running water, but are more likely the result of the seasonal dust/wind storms
NASA on Mars • NASA began sending meaningful missions to Mars in 1971 (Mariner 9) • The satellites photographed a large valley in the surface that may have been carved out by water. (it would stretch from California to New York) VallesMarineris
Satellites and Mars Missions • Mariner 9 • Viking • Mars Global Surveyor • Mars Pathfinder • Odyssey • Mars Exploration Rover Mission (Spirit and Opportunity)
Viking Probes (1976) The two probes, Viking I and Viking II photographed the surface and landed taking rock samples and looking for signs of life
Global Surveyor, Pathfinder, and Odyssey • These three missions photographed the walls of the VallesMarineris and found it to be layered. Does that indicate sedimentary rock (water) or is it volcanic in nature?
Mars Exploration Rover Mission (2003) These “rovers” found deposits of hematite that are usually the result of crystallization in standing water.
Martian Meteorites • Meteorites have also been found on Earth that are believed to have come from the surface of Mars as the result of impact. • A meteorite from Mars (ALH84001) was found in 1996 in Antarctica and appeared to show fossilized microorganisms.
Section 8-3The Outer Planets Objectives: • Compare and contrast the outer planets • Describe the important characteristics for each outer planet • Evaluate the success of NASA missions Galileo and Cassini