# Copyright © 2010 Pearson Education, Inc. Chapter 4 The Solar System.

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Copyright © 2010 Pearson Education, Inc. Chapter 4 The Solar System

Copyright © 2010 Pearson Education, Inc. EXAM 1 Average 71 Median 72

Copyright © 2010 Pearson Education, Inc. Tough Questions Copernicus’ Heliocentric theory explains that… Venus retrogrades when she overtakes us at an inferior conjunction The sun lies at one focus of an ellipse Mars will retrograde when it reaches a certain position on its epicycle All planets lie between the Sun and Earth

Copyright © 2010 Pearson Education, Inc. If a new wave arrives on shore every two seconds, then its frequency is 2 Hz. False It would be ½ Hz or 1 per 2 seconds 2 Hz would be 2 per second

Copyright © 2010 Pearson Education, Inc. Doubling the temperature of a black body will double the total energy it radiates. False F =  T 4 If you were to double T then F would be 16x bigger.

Copyright © 2010 Pearson Education, Inc. What is the light gathering power of an 8 inch telescope compared to a 4 inch telescope? 4x better Light gathering depends on the area. Area =  r 2 4 is twice as big as 8 so area is 4 times

Copyright © 2010 Pearson Education, Inc. The opacity of the atmosphere is partially corrected via adaptive optics. False Adaptive optics can correct for atmospheric turbulence but not opacity such as clouds or smog.

Copyright © 2010 Pearson Education, Inc. Example Questions Of those examples I gave in class that appeared on the exam 68% got them correct.

Copyright © 2010 Pearson Education, Inc. Chapter 4 The Solar System

Copyright © 2010 Pearson Education, Inc. Units of Chapter 4 An Inventory of the Solar System Interplanetary Matter The Formation of the Solar System Planets Beyond the Solar System

Copyright © 2010 Pearson Education, Inc. Early astronomers knew Moon, stars, Mercury, Venus, Mars, Jupiter, Saturn, comets, and meteors. Now known: Solar system has 166 moons, one star, eight planets (added Uranus and Neptune), asteroids, comets, meteoroids, dwarf planets, and Kuiper Belt objects. An Inventory of the Solar System

Copyright © 2010 Pearson Education, Inc. An Inventory of the Solar System

Copyright © 2010 Pearson Education, Inc. Distance from Sun known by Kepler’s laws. Orbital period can be observed. Radius known from angular size. Masses known from Newton’s laws. Rotation period known from observations. Density can be calculated knowing radius and mass. An Inventory of the Solar System

Copyright © 2010 Pearson Education, Inc. All orbits but Mercury’s are close to the same plane. An Inventory of the Solar System

Copyright © 2010 Pearson Education, Inc. An Inventory of the Solar System

Question 1 Which of the following are terrestrial planets? a)only Earth b)Earth, Moon, and Venus c)Mercury, Venus, Earth, and Mars d)Mercury, Venus, Earth, Moon, Mars, and Pluto e)Mercury, Venus, Earth, Moon, Mars, and Ceres

Question 1 Which of the following are terrestrial planets? a)only Earth b)Earth, Moon, and Venus c)Mercury, Venus, Earth, and Mars d)Mercury, Venus, Earth, Moon, Mars, and Pluto e)Mercury, Venus, Earth, Moon, Mars, and Ceres Terrestrial planets are “Earth-like.”

Copyright © 2010 Pearson Education, Inc. Terrestrial planets: Mercury, Venus, Earth, Mars Jovian planets: Jupiter, Saturn, Uranus, Neptune An Inventory of the Solar System

Mass and Density Mass: how much “stuff” something has. Density: how much “stuff” something has in a certain size (volume)

Question 2 The major difference(s) between the terrestrial and jovian planets involve(s) a) mass. b) density. c) rotation speed. d) density and rotation speed. e) mass and density.

Question 2 The major difference(s) between the terrestrial and jovian planets involve(s) a) mass. b) density. c) rotation speed. d) density and rotation speed. e) mass and density. Jovian planets are more massive, but less dense, than terrestrial planets.

Copyright © 2010 Pearson Education, Inc. Differences between the terrestrial planets: Atmospheres and surface conditions are very dissimilar. Only Earth has oxygen in atmosphere and liquid water on surface. **Goldilocks** Earth and Mars rotate at about the same rate; Venus and Mercury are much slower, and Venus rotates in the opposite direction. Earth and Mars have moons; Mercury and Venus don’t. Earth and Mercury have magnetic fields; Venus and Mars don’t. An Inventory of the Solar System

Question 3 Which of the following defines density? a) mass times surface gravity b) mass divided by volume c) size divided by weight d) mass times surface area e) weight divided by size

Question 3 Which of the following defines density? a) mass times surface gravity b) mass divided by volume c) size divided by weight d) mass times surface area e) weight divided by size Density can be thought of as MATTER SPACE gm/cm 3 Lots of matter in a small space = HIGH density. Little matter in a large space = LOW density.

Question 4 Compared with terrestrial planets, jovian planets share all of the following characteristics EXCEPT a) low density. b) large size. c) many moons. d) ring systems. e) slower rotation.

Question 4 Jovian planets share all of the following characteristics EXCEPT a) low density. b) large size. c) many moons. d) ring systems. e) Slow rotation.

Copyright © 2010 Pearson Education, Inc. Interplanetary Matter The inner solar system, showing the asteroid belt, Earth-crossing asteroids, and Trojan asteroids

a) beyond the orbit of Neptune. b) between Earth and the Sun. c) between Mars and Jupiter. d) in the orbit of Jupiter, but 60 degrees ahead or behind it. e) orbiting the jovian planets in captured, retrograde orbits. Most asteroids are found Question 5

a) beyond the orbit of Neptune. b) between Earth and the Sun. c) between Mars and Jupiter. d) in the orbit of Jupiter, but 60 degrees ahead or behind it. e) orbiting the jovian planets in captured, retrograde orbits. Question 5 Most asteroids are found The Asteroid Belt is located between 2.1 and 3.3 A U from the Sun.

Question 6 The asteroid belt is evidence of a) a planet that once orbited the Sun but later was destroyed. b) ancient material from the formation of the solar system. c) a collision between Jupiter and one of its larger moons. d) comets that were trapped by Jupiter’s gravitational field.

Question 6 The asteroid belt is evidence of a) a planet that once orbited the Sun but later was destroyed. b) ancient material from the formation of the solar system. c) a collision between Jupiter and one of its larger moons. d) comets that were trapped by Jupiter’s gravitational field. Asteroids, meteoroids, and comets may have not changed at all since the solar system formed.

Copyright © 2010 Pearson Education, Inc. Interplanetary Matter Large picture: The path of Icarus, an Earth-crossing asteroid Inset: Ceres, the largest asteroid

Copyright © 2010 Pearson Education, Inc. Asteroids and meteoroids have rocky composition; asteroids are bigger. (above) Asteroid Ida with its moon, Dactyl (below) Asteroid Gaspra (above) Asteroid Mathilde Interplanetary Matter

VESTA - July 2011: 10% of main asteroid belt mass ~530 km in dia.

Question 7 Compared to asteroids, comets show all of these properties EXCEPT a)their densities are higher. b)their orbits tend to be more elliptical. c)they tend to be made of ice. d)they can look fuzzy, whereas asteroids appear as moving points of light. e)their average distances from the Sun are far greater.

Question 7 Compared to asteroids, comets show all of these properties EXCEPT Comets have densities much lower than asteroids or planets. a)their densities are higher. b)their orbits tend to be more elliptical. c)they tend to be made of ice. d)they can look fuzzy, whereas asteroids appear as moving points of light. e)their average distances from the Sun are far greater.

Copyright © 2010 Pearson Education, Inc. What Killed the Dinosaurs? The larger an impact is, the less often we expect it to occur. The dinosaurs may have been killed by the impact of a large meteor or small asteroid.

Copyright © 2010 Pearson Education, Inc. Interplanetary Matter Deep Impact Tempel 1 Asteroid Eros

Copyright © 2010 Pearson Education, Inc. Comets are icy, with some rocky parts. The basic components of a comet Interplanetary Matter

Copyright © 2010 Pearson Education, Inc. Interplanetary Matter The solar wind means the ion tail always points away from the Sun. The dust tail also tends to point away from the Sun, but the dust particles are more massive and lag somewhat, forming a curved tail.

Copyright © 2010 Pearson Education, Inc. Interplanetary Matter The internal structure of the cometary nucleus

Copyright © 2010 Pearson Education, Inc. Interplanetary Matter The size, shape, and orientation of cometary orbits depend on their location. Oort cloud comets rarely enter the inner solar system.

What causes a meteor shower? Question 8 a) A comet and an asteroid collide. b) Earth runs into a stray swarm of asteroids. c) Earth runs into the debris of an old comet littering its orbit. d) Meteorites are ejected from the Moon. e) Debris from a supernova enters Earth’s atmosphere

What causes a meteor shower? Question 8 Meteor showers can generate a few shooting stars, to hundreds of thousands, seen in an hour. a) A comet and an asteroid collide. b) Earth runs into a stray swarm of asteroids. c) Earth runs into the debris of an old comet littering its orbit. d) Meteorites are ejected from the Moon. e) Debris from a supernova enters Earth’s atmosphere

Copyright © 2010 Pearson Education, Inc. Interplanetary Matter Meteor showers are associated with comets – they are the debris left over when a comet breaks up.

Copyright © 2010 Pearson Education, Inc. Interplanetary Matter

Copyright © 2010 Pearson Education, Inc. Interplanetary Matter The impact of a large meteor can create a significant crater. The Barringer meteor crater in Arizona

Copyright © 2010 Pearson Education, Inc. Interplanetary Matter The Manicouagan reservoir in Quebec

Question 9 Any theory of the origin of the solar system must explain all of these EXCEPT a) the orbits of the planets are nearly circular, and in the same plane. b) the direction that planets orbit the Sun is opposite to the Sun’s spin. c) the terrestrial planets have higher density and lower mass. d) comets do not necessarily orbit in the plane of the solar system.

Question 9 Any theory of the origin of the solar system must explain all of these EXCEPT a) the orbits of the planets are nearly circular, and in the same plane. b) the direction that planets orbit the Sun is opposite to the Sun’s spin. c) the terrestrial planets have higher density and lower mass. d) comets do not necessarily orbit in the plane of the solar system. The planets do orbit in the same direction that the Sun spins. Most also spin in that direction, and most also have large moons that orbit in that direction.

Copyright © 2010 Pearson Education, Inc. Condensation theory: Interstellar dust grains help cool cloud, and act as condensation nuclei. The Formation of the Solar System

Copyright © 2010 Pearson Education, Inc. Nebular contraction: Cloud of gas and dust contracts due to gravity; conservation of angular momentum means it spins faster and faster as it contracts. Formation of the Solar System

Copyright © 2010 Pearson Education, Inc. Conservation of angular momentum says that product of radius and rotation rate must be constant. Therefore, as a dust cloud collapses, its rate of rotation will increase. The Concept of Angular Momentum

Copyright © 2010 Pearson Education, Inc. Temperature in cloud determines where various materials condense out; this determines where rocky planets and gas giants form. The Formation of the Solar System

Question 10 The condensation sequence theory explains why a) our planet Earth has water and rain. b) stars are more likely to form large planets orbiting very near. c) terrestrial planets are different from jovian planets. d) the Moon formed near the Earth. e) Pluto has such a circular orbit.

Question 10 The condensation sequence theory explains why a) our planet Earth has water and rain. b) stars are more likely to form large planets orbiting very near. c) terrestrial planets are different from jovian planets. d) the Moon formed near to Earth. e) Pluto has such a circular orbit. The condensation sequence theory explains how the temperature of the early solar nebula controls which materials are solid, and which are gaseous.

Copyright © 2010 Pearson Education, Inc. The Formation of the Solar System The star Beta Pictoris is surrounded by a disk of warm matter, which may indicate planetary formation.

Copyright © 2010 Pearson Education, Inc. The Formation of the Solar System These images show possible planetary systems in the process of formation.

Copyright © 2010 Pearson Education, Inc. Planets Beyond the Solar System Many planets have been discovered in other solar systems; this is one that is visible.

Question 11 Astronomers have detected most extrasolar planets by observing a) the “wobble” of their parent stars using spectroscopy. b) starlight reflected by their surfaces. c) eclipses when the planets block the light of their parent stars. d) the planets’ changing phases as they orbit their stars.

Question 13 Astronomers have detected most extrasolar planets by observing a) the “wobble” of their parent stars using spectroscopy. b) starlight reflected by their surfaces. c) eclipses when the planets block the light of their parent stars. d) the planets’ changing phases as they orbit their stars. Measurements of the periodic Doppler shift in the spectra of the star 51 Pegasi indicate it has a planetary companion.

Copyright © 2010 Pearson Education, Inc. Planets Beyond the Solar System Some planets are discovered through the “wobble” they create in their parent star’s orbit.

Copyright © 2010 Pearson Education, Inc. Others are discovered through the periodic dimming of the parent star’s luminosity. Planets Beyond the Solar System

Copyright © 2010 Pearson Education, Inc. Planets Beyond the Solar System These are the orbits of many extra-solar planets discovered so far. Most have masses closer to that of Jupiter than that of Earth.

Question 12 Extrasolar planets the size of Earth have NOT been seen yet with current techniques because a) small planets probably don’t exist. b) the large planets nearby have swept them up. c) Earth-like planets take time to form. d) large planets orbiting near to their stars are more easily detected. e) small planets can only be seen if they cross in front of their star.

Question 12 Extrasolar planets the size of Earth have NOT been seen yet with current techniques because a) small planets probably don’t exist. b) the large planets nearby have swept them up. c) Earth-like planets take time to form. d) large planets orbiting near to their stars are more easily detected. e) small planets can only be seen if they cross in front of their star. Looking for detectable “wobbles” in the spectra of stars finds massive planets with small orbits. Other techniques may be needed to see less massive Earth-like planets.

Copyright © 2010 Pearson Education, Inc. Solar system consists of Sun and everything orbiting it. Asteroids are rocky, and most orbit between orbits of Mars and Jupiter. Comets are icy, and are believed to have formed early in the solar system’s life. Major planets orbit Sun in same sense, and all but Venus rotate in that sense as well. Planetary orbits lie almost in the same plane. Summary of Chapter 4

Copyright © 2010 Pearson Education, Inc. Four inner planets – terrestrial planets – are rocky, small, and dense. Four outer planets – Jovian planets – are gaseous and large. Nebular theory of solar system formation: Cloud of gas and dust gradually collapsed under its own gravity, spinning faster as it shrank. Condensation theory says dust grains acted as condensation nuclei, beginning formation of larger objects. Summary of Chapter 4, cont.

Copyright © 2010 Pearson Education, Inc. Summary of Chapter 4, cont. Planets have been discovered in other solar systems. Most are large and orbit much closer to the Sun than the large planets in our solar system do.