AST 115 1st EditionExam # 2 Study Guide Lectures: 12 - 18Lecture 12 (February 13)Properties of the Planets of the Solar System- Be able to describe and compare the various properties of the major planets in our solar system.Planet Diameter (Earth = 1.0) Mass (Earth = 1.0) Average Density (gm/cm3)Mercury 0.4 0.06 5.4Venus 1 0.8 5.2Earth 1.0 1.0 5.5Mars 0.5 0.1 3.9Jupiter 11 318 1.3Saturn 9.5 95 0.7Uranus 4 15 1.3Neptune 3.9 17 1.6( Pluto 0.2 0.0025 2 )- Be able to list the 8 major planets in order from the Sun.(1) Mercury(2) Venus(3) Earth(4) Mars(5) Jupiter(6) Saturn(7) Uranus(8) Neptune - What are the Terrestrial planets? What are they composed of? What two planets are considered the “twins” of the Terrestrial planets? The four inner planets: Mercury, Venus, Earth, and Mars are the Terrestrial planets. These planetsare mostly made up of rocky, denser material. Venus and Earth are considered the “twins” of the Terrestrial planets, although they are not completely identical.- What are the Jovian planets? What are they composed of? Which two planets are considered the “twins” of the Jovian planets? Which of the Jovian planets is referred to as the “King of the Planets”? Why is Pluto not considered to be part of the Jovian planets anymore? Which Jovian planet would float in water if you were to find a bathtub big enough to fit it in? The four outer planets: Jupiter, Saturn, Uranus, and Neptune are the Jovian planets. They are made up of gaseous materials. Uranus and Neptune are considered the “twins” of the Jovian planets, although they are not completely identical. Jupiter is sometimes referred to as the “King of the Planets” because of its large diameter and mass. Jupiter also has four huge satellites (Ganymede, Callisto, Io, and Pluto). Pluto used to be part of the Jovian planets, but it has since been re-classified as a Dwarf Planet because of its very small size and mass compared to the rest of the 8 major planets. Saturn’s average density is 0.7 gm/cm3, which is lower than the density of water. This low density would cause Saturn to float on top of water.- Be able to compare the following properties of the Terrestrial and Jovian planets: average density, moons/satellites, rings, atmosphere, and rotation rate. Terrestrial planets: Have high average densities. Have few moons/satellites.Have no rings.Have an atmosphere described as “thin”.Have a rotation rate that would be described as “slow” Jovian planets:Have low average densities.Have many moons/satellites.All four of the Jovian planets have rings.Have an atmosphere described as “thick”.Have a rotation rate that would be described as “fast”.Lecture 13 (February 20)Regulatories of the Solar System- What are the four ways you would describe the orbits of the 8 major planets? The orbits of the 8 major planets are (1) nearly in the same plane/ecliptic, (2) in the same direction, (3) nearly circular, (4) regularly spaced [not equally spaced].- Is Pluto in the same plane as the rest of the 8 major planets? No. This is part of the reason why it was re-classified as a dwarf planet.- Which two planets rotate in retrograde motion (spin backwards)? What is the cause of this? Venus and Uranus rotate in retrograde motion. Astronomers believe that Uranus was struck by anobject a long time ago causing it to rotate backwards. Astronomers have not yet discovered why Venus spins backwards.- What are the two distinct types of planets? Terrestrial and JovianAge of the Solar System- How was the age of the solar system determined? According to the theory for the formation of the solar system, how long ago did our solar system form? Radioactive dating of rock samples from the Earth, Moon and meteorites have made it possible for scientists to determine the formation of the solar system. The solar system is estimated to have formed about 4.6 billion years ago. The theory of the formation of the Sun dates back to about this same time.Building Materials for the Solar System- Be able to recognize and apply the following equation:Average Density=MassVolume- What are the basic “ingredients” for making the solar system objects? What are some examples of each ofthe “ingredients”? Be able to give each of their average densities. The basic ingredients for making the solar system objects are “metals” with an average density of 10 g/cm3 (iron, nickel), “rocks” with an average density of 3 g/cm3 (silicates mixed with magnesium, sulfur…), “gases” with an average density of ˂ 1 g/cm3 (hydrogen, helium), and “ices” with an average density of 1 g/cm3 (H2O = water, C O2 = Carbon Dioxide,NH3 = ammonia, CH4 = methane). Mixtures of different proportions of these building materials can match the observed average densities of objects. The Solar Nebula Theory and the “Nice” Model- What is the Solar Nebula Theory? Explain and describe. The universe began in an extremely hot and dense state about 14 billion years ago. After a few minutes, the temperature had dropped low enough for matter to form from energy. Essentially, only hydrogen and helium were produced during this “cool down” period. About 9 billion years later, the Sun and the planets formed, at about the same time, from material in an interstellar cloud. Small amounts of “heavier” elements must have been present from past supernova explosions. These elements were produced in the cores of stars that became supernova explosions. After being compressed, probably by another nearby supernova explosion, the solar nebula began gravitational contraction. During this process, the spinning nebula flattened into a disk with a central concentration. This central concentration is referred to as the protosun. Gravitational contraction of the protosun released energy to heat it to a temperature that was about 10 million ˚K, at which it fuses. Meanwhile, the gas, ice, and dust in the disk slowly accreted to produce the planets. The inner part of the disk was warmed by radiation from the protosun. Only rocky and metallic particles were left behind. Beyond the snow line (or frost line), gases and icy particles were also present.- What is the Nice Model (pronounced “niece” model)? Details of the Solar Nebula Theory that emerged from supercomputer simulations.Lecture 14 (February 23)Formation of the Outer Planets- What is the order of the formation of the outer planets?