Presentation on theme: "Solar System 2011 Presented by Linder Winter. PARTICIPANT SIGN-IN SHEET Please enter your name, address and email on the Participant Sign-In Sheets."— Presentation transcript:
Solar System 2011 Presented by Linder Winter
PARTICIPANT SIGN-IN SHEET Please enter your name, address and on the Participant Sign-In Sheets which have been placed on the tables throughout the room. NASA’S Chandra X-ray Center sponsors the lodging, food, transportation, and other expenses associated with my role as a presenter, provides the materials distributed to participants attending my workshop sessions, and my participation as an Event Supervisor at the NSO Finals each year. Chandra may contact you to ask whether the instruction and materials provided during this workshop have been helpful to you. Your personal information is used solely for the purpose stated above. High numbers of workshop attendees are an important factor to my continued support from NASA’s Chandra X-ray Center.
PRESENTATION OUTLINE Part I: Event Rules Part II: Coaching strategies Part III: Topics covered in this event Part IV: Resources
SOLAR SYSTEM Astronomy B-Division – Rotation Scheme: 2010 & 2011 Solar System 2012 & 2013 Reach for the Stars Repeat sequence …
PART I: EVENT RULES The Solar System
EVENT DESCRIPTION This event will address: The Sun 8 Planets and their natural satellites 5 Dwarf planets Comets Asteroids and the asteroid belt Meteoroids Kuiper Belt Oort Cloud
EVENT DESCRIPTION A TEAM OF UP TO: 2 APPROXIMATE TIME: 50 Minutes
EVENT PARAMETERS Teams may bring only one 8.5” x 11” two-sided sheet of notes containing images, graphics and text, plus a basic, non-programmable calculator with a square root function.
THE COMPETITION Participants will be presented with one or more tasks, each requiring the use of one or more process skills. Skills may include, but are not limited to, generating inferences, making predictions, problem solving, making and recording observations, formulating and evaluating hypotheses, interpreting data and graphing.
THE COMPETITION The exam may be presented using a thematic approach.
SCORING Points will be awarded for the quality and accuracy of responses. Ties will be broken by the accuracy or quality of answers to selected questions.
NATIONAL SCIENCE EDUCATION STANDARDS Applicable National Science Standards have been identified for each of the Earth-Space events. Including these in the rules provides justification for use of Science Olympiad materials in the classroom.
NATIONAL SCIENCE EDUCATION STANDARDS Earth and Space Science, Content Standard D: Structure of the Earth System; Earth’s History; Earth in the Solar System. Content Standard B: Motions and Forces: Transfer of Energy. Examples: (1) As the Earth slows down due to friction of its waters with the ocean basin, the Moon moves further away. (2) As solar particles escape the Sun, magnetic braking occurs. This momentum is transferred to the orbiting planets.
MISCONCEPTIONS Much of what we presently know about the solar system has proven previous information to be false, inaccurate or simply incorrect. Many of our misconceptions are a result of our own misinterpretations, while others are a result of the misinterpretations of others. Some are based on myths and legends that have been accepted for so long that they are seldom challenged. A few of these follow:
HELIOCENTRIC MYTHS It is a myth that the heliocentric model was more accurate in its predictions than the geometric model.
HELIOCENTRIC MYTHS It is a myth that the heliocentric model was much simpler than the geocentric model.
HELIOCENTRIC MYTHS It is a myth that Copernicus delayed publishing for fear of reprisal from the church.
HELIOCENTRIC MYTHS It is a myth that astronomers quickly embraced the heliocentric model.
HELIOCENTRIC MYTHS It is a myth that Galileo proved the heliocentric model to be correct.
PART II: COACHING STRATEGIES The Solar System
CHANGING TIMES Modern telescopes and recent planetary missions have greatly modified and increased our knowledge of the solar system. In preparing for this event, participants should be encouraged to seek out recent, authoritative books and articles. (Unfortunately, this excludes many textbooks!)
OUR CHANGING SOLAR SYSTEM FORMER SOLAR SYSTEM MODIFIED SOLAR SYSTEM MODEL
COACHING STRATEGIES: SELECTING EVENT PARTICIPANTS Individuals who appear to be the strongest candidates in the early stages of preparation may prove otherwise in the long run. Encourage as many candidates as possible to compete for a position on the team for this event. Should a participant drop out of the event or a “last minute” scheduling conflict arises, you’ll have someone prepared to assume that position. Identify the role of each team member, i.e. leader and assistant.
COACHING STRATEGIES: SELECTING EVENT PARTICIPANTS Avoid choosing and announcing the names of the final participants too early. As long as an opportunity exists to be chosen for participation, many students will continue to study and prepare. Once their position on the team has been assured, those chosen as finalists may drastically reduce their preparation time.
COACHING STRATEGIES: RESOURCES Anticipate more challenging questions and activities for those events permitting the use of resources. The goal is to develop concepts rather than memorize numerous facts which, in and of themselves, are frequently meaningless and easily forgotten. Experienced event supervisors will most likely limit or avoid questions and activities emphasizing purely factual information that can be referenced very quickly and easily.
COACHING STRATEGIES: RESOURCE DESIGN Encourage students to make their resource pages a “working document.” As students begin to feel comfortable with certain facts and concepts they’ve included in their notes, encourage them to remove those to be replaced by others.
COACHING STRATEGIES: SUGGESTED CONTENTS FOR RESOURCE PAGES Brief notes about each member or group composing the solar system Newton’s and Kepler’s laws with accompanying information Star charts identifying the positions of all planets in the sky on the night of the competition Glossary of important terms
REPRESENTATIVE TASKS Interpretation and construction of charts, graphs and data tables Interpretation of photos, images, maps and diagrams Matching applicable laws to stated scenarios Sequencing events such as geological processes on planetary surfaces Locating and/or identifying the positions of planets present in the night skies on the evening of the competition
REPRESENTATIVE TASKS Calculating the orbital period of a planet when its distance in AUs is known. AU = Astronomical Units (distance from Earth to the Sun = 1 AU)
KNOWLEDGE vs. CONCEPTUALLY-BASED LEARNING In preparing your team, select relevant images, graphs, charts, tables, etc. and challenge participants to use these in developing their own lists of questions, tasks and activities. Providing opportunities to develop sound conceptual thinking skills is the most effective type of preparation for SO competitions.
VOLUNTEER COACHES If you identify someone willing to coach the Solar System event, provide him/her with a copy of this PowerPoint presentation to serve as an introduction to the event and what will be expected of the participants.
CREDITS Credits for all material acquired from the internet for use in this presentation are provided at the end of this PowerPoint and serve two purposes: 1.To meet the standard requirement for fair use practices and … 2. To assist students to locate URLs of quality sites that support the event topic.
PART III: EVENT TOPICS The Solar System
EVENT TOPICS Each of the topics included in the Solar System event will be introduced in the next series of slides. This series of slides may be used to introduce the event to students who have expressed a desire to compete in this event.
HISTORY AND FORMATION OF THE SOLARS SYSTEM Much of our knowledge of how the solar system was formed is gained from direct observations of objects within other galaxies and solar systems – both younger and older. Image: Northrop Grumman Corporation
HISTORY AND FORMATION OF THE SOLARS SYSTEM The planets of the Solar System formed from a nebula of gas, dust, and ices coalescing into a dusty disk around the evolving Sun. Within the disk, tiny dust grains and ices coagulated into growing bodies called planetesimals. Image: Pat Rawlings, NASA
HISTORY AND FORMATION OF THE SOLARS SYSTEM Over a period as long as 100 million years, many of these planetesimals accreted into planets. Image: Pat Rawlings, NASA
OBJECTS OF THE SOLAR SYSTEM: SUN Age and size Prominences, flares Sunspots & the solar cycle activity Corona, photosphere, chromosphere Stages of evolution Energy production Core, radiative, and convective zones Solar wind Illustration: Courtesy SOHO
OBJECTS OF THE SOLAR SYSTEM: SUN Prominences are dense clouds of material suspended above the surface of the Sun by loops of magnetic field. Prominences and filaments are actually the same objects, except that promi-nences are seen projecting out above the limb of the Sun.
OBJECTS OF THE SOLAR SYSTEM: SUN Spicules are small, jet- like eruptions. Spicules appear as short dark streaks. Although spicules last just a few minutes they eject material off of the surface and outward into the hot corona at speeds of 20 to 30 km/s.
OBJECTS OF THE SOLAR SYSTEM: SUN Solar flares are tremendous explosions on the surface of the Sun. Solar flares occur near sunspots between areas of oppositely directed magnetic fields.
OBJECTS OF THE SOLAR SYSTEM: SUN Coronal Mass Ejections or (CMEs) are huge bubbles of gas threaded with magnetic field lines that are ejected from the Sun over the course of several hours.
OBJECTS OF THE SOLAR SYSTEM: SUN Coronal Mass Ejections disrupt the flow of the solar wind and produce disturbances that strike the Earth with sometimes catastrophic results.
OBJECTS OF THE SOLAR SYSTEM: SUN Coronal mass ejections are often associated with solar flares and prominence eruptions, but they can also occur in the absence of either of these processes.
OBJECTS OF THE SOLAR SYSTEM: SUN The Sun's core is the central region where nuclear reactions consume hydrogen to form helium. These reactions release the energy that ultimately leaves the surface as visible light.
OBJECTS OF THE SOLAR SYSTEM: SUN The radiative zone extends outward from the outer edge of the core to the interface. The radiative zone is characterized by its method of energy transport - radiation. Energy generated in the core is carried by light that bounces from particle to particle through the radiative zone.
OBJECTS OF THE SOLAR SYSTEM: SUN The interface layer lies between the radiative zone and the convective zone. The fluid motions found in the convec-tion zone slowly disappear from the top of this layer to its bottom where the conditions match those of the calm radiative zone.
OBJECTS OF THE SOLAR SYSTEM: SUN It is now believed that the Sun's magnetic field is generated by a magnetic dynamo in the interface layer. Changes in fluid flow velocities across the layer can stretch magnetic field lines of force and make them stronger.
OBJECTS OF THE SOLAR SYSTEM: SUN The convective zone is the outermost layer of the solar interior. It extends from a depth of about 200,000 km right up to the visible surface. Convective motions carry heat to the surface. These motions are visible at the surface as granules and super-granules.
OBJECTS OF THE SOLAR SYSTEM: PLANETS According to the International Astronomical Union (IAU), a planet is a celestial body that: Is in orbit around the Sun, Has sufficient mass to assume a hydrostatic equilibrium (nearly round) shape, and Has “cleared the neighbor-hood” around its orbit. This definition does not apply outside the solar system. e_tour.htm
OBJECTS OF THE SOLAR SYSTEM: DWARF PLANETS According to the IAU, a dwarf planet: Is in orbit around the Sun Has sufficient mass for its self- gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, Has not “cleared the neighbor- hood” around its orbit, and Is not a satellite of a planet, or other nonstellar body. e_tour.htm
OBJECTS OF THE SOLAR SYSTEM: DWARF PLANETS There are currently five official dwarf planets. Pluto was demoted to dwarf planet status. Ceres, the largest asteroid in the main asteroid belt between Mars and Jupiter, was also declared a dwarf planet. Images courtesy of NASA, ESA, JPL, and A. Feild (STScI).
OBJECTS OF THE SOLAR SYSTEM: DWARF PLANETS The three other dwarf planets are Eris, Make-make and Haumea. Pluto, Makemake and Haumea orbit the Sun on the frozen fringes of our Solar System in the Kuiper Belt. Eris, a Trans-Neptunian Object, is located even further from the Sun. Images courtesy of NASA, ESA, JPL, and A. Feild (STScI).
OBJECTS OF THE SOLAR SYSTEM: DWARF PLANETS Haumea is a large Kuiper Belt Object (KBO). It is an icy world that orbits far from the Sun on the frozen fringes of our Solar System. Because it is so far away, Haumea takes 285 years to orbit the Sun once! Haumea is usually a bit further from the Sun than Pluto. Images courtesy of NASA, ESA, JPL, and A. Feild (STScI).
OBJECTS OF THE SOLAR SYSTEM: DWARF PLANETS What, do you suppose, causes this dwarf planet’s strange shape? Which arrow, red or blue, represents the object’s most likely spin axis? Explain. Images courtesy of NASA, ESA, JPL, and A. Feild (STScI).
OBJECTS OF THE SOLAR SYSTEM: DWARF PLANETS What, do you suppose, causes this dwarf planet’s strange shape? Its rapid rotation. Which arrow, red or blue, represents the object’s most likely spin axis? Explain. Blue. It bulges outward along this line. Images courtesy of NASA, ESA, JPL, and A. Feild (STScI).
OBJECTS OF THE SOLAR SYSTEM: RING SYSTEMS Planetary rings are thought to have been created when small moons collided with others, or ventured too close to their parent planet.
OBJECTS OF THE SOLAR SYSTEM: RING SYSTEMS The resulting fragments gradually spread out into concentric orbits, breaking into ever smaller fragments through repeated collisions, eventually forming a ring system.
OBJECTS OF THE SOLAR SYSTEM: RING SYSTEMS Ring systems are thought to be a somewhat transient phenomena, lasting perhaps only several hundred million years.
OBJECTS OF THE SOLAR SYSTEM: RING SYSTEMS Climates Effects of atmospheres Composition Density Orbital eccentricity Distance from the Sun Rotational rate Axial tilt Presence of surface liquids Planetary size Albedo Solar wind
OBJECTS OF THE SOLAR SYSTEM: PLANETS Seasons Extraterrestrial seasons are hardly noticeable on some planets (Venus), extreme on others (Uranus), and in some cases impossible to define (Mercury). Planetary seasons result from two factors: (1) axial tilt (2) variable distance from the sun (orbital eccentricity) Any planet that has a tilted axis has seasons.
OBJECTS OF THE SOLAR SYSTEM: TIDAL EFFECTS The gravity of Jupiter and its large moons yank Io every which way. Io’s "solid ground" tides are more than five times as high as Earth’s highest ocean tides!
OBJECTS OF THE SOLAR SYSTEM: TIDAL EFFECTS Earth has solid ground tides also, but they amount to less than 20 centimeters (about 8 inches).
OBJECTS OF THE SOLAR SYSTEM: ASTEROIDS The heaviest concentration of asteroids is in a region lying between the orbits of Mars and Jupiter called the asteroid belt.
OBJECTS OF THE SOLAR SYSTEM: ASTEROIDS Some 7000 asteroids have been identified so far. It is likely that the origin of the asteroid belt lies in the gravitational perturbation of Jupiter, which kept these planetisimals from coalescing into larger bodies. The figure above shows the asteroid Gaspra which was investigated by the Galileo spacecraft
OBJECTS OF THE SOLAR SYSTEM: ASTEROIDS Asteroid orbit distributions show evidence for Kirkwood Gaps, which are certain orbital radii within the asteroid belt for which there are few asteroids. They result from resonance interactions with Jupiter (values shown) that tend to eject asteroids from such orbits. 3:15:27:32:1
OBJECTS OF THE SOLAR SYSTEM: IMPACT CRATERS Impact craters are formed when a large meteoroid (asteroid or comet) crashes into a larger planetary body that has a solid surface. Image courtesy of David Roddy, USGS
OBJECTS OF THE SOLAR SYSTEM: METEORS When a meteoroid enters the atmosphere at high velocity, friction causes it to incinerate in a streak of light. This streak of light is called a meteor. Meteorites are sometimes called “shooting stars.” Most meteorites originate from material released from comets.
OBJECTS OF THE SOLAR SYSTEM: METEOR SHOWERS Meteor showers are named for the constellations from which they appear to radiate. The timing of meteor showers is predictable due to known orbits of defunct comets.
OBJECTS OF THE SOLAR SYSTEM: METEOROIDS A meteoroid is matter revolving around the sun or any object in interplanetary space that is too small to be called an asteroid or a comet. Unofficially the size limit for an asteroid has been set at 50 meters; anything smaller than that is simply called a meteoroid.
OBJECTS OF THE SOLAR SYSTEM: COMETS Composition: water, carbon dioxide, ammonia, and methane ices, with mixed-in dust Origins of short-period vs. long-period comets Parts: head, coma and tails: ion (gas) tail, dust tail Why they glow: reflection of light and gases being excited by sunlight emitting electromagnetic radiation Disturbances that cause comets to leave their home in the Kuiper belt or Oort Cloud … passing star, etc Influence of Jovian planets on their orbits
OBJECTS OF THE SOLAR SYSTEM: COMETS The center of a comet's head is called its nucleus. The nucleus is a few kilometers across and is surrounded by a diffuse, bright region called the coma that may be a million kilometers in diameter. The coma is formed from gas and dust ejected from the nucleus as it is heated by the Sun. The coma is bright both because it reflects sunlight and because its gases are excited by sunlight and emit electromagnetic radiation.
OBJECTS OF THE SOLAR SYSTEM: COMETS Short-period comets are the most common. They have only mildly elliptical orbits that carry them out to a region lying from Jupiter to beyond the orbit of Neptune. (Illustrated: Location of Halley’s Comet in the year 2024)
FACTS ABOUT THE ASTEROID BELT The total weight of all the asteroids in the asteroid belt is about 1/35th of that of our moon! Ceres, the largest asteroid, is about 1/3 the total weight of all the asteroids! Even though there are a lot of asteroids, the asteroid belt is mostly empty space. Traveling through the asteroid belt in a space ship would not be very much like what you see in a science fiction film. In addition to the belt asteroids, there are others based upon their location and orbit in the solar system: Apollo, Amors, Atons, Trojan and Centaurs.
KUIPER BELT The Kuiper Belt is made up of millions of icy and rocky objects that orbit our Sun beyond the orbits of Neptune and Pluto. Scientists think the gravity of big planets like Jupiter and Saturn swept all these icy leftovers out to the edge of our solar system. Missions to Kuiper Belt: New Horizons After it flies past Pluto and Charon, New Horizons will head into the Kuiper Belt. It will be the first spacecraft to explore this mysterious region.
OBJECTS OF THE SOLAR SYSTEM; OORT CLOUD In 1950 Jan Oort noticed that no comet had been observed coming from interstellar space. Instead, all long period comets, normally have orbits that lie at a great distance and have no preferential direction of entry. For these reasons Oort deduced the existence of a vast cloud of comets having the shape of a diffuse spherical shell at about 50,000 AU from the Sun. This cloud of comets was named the “Oort Cloud” in honor of Jan Oort.
OBJECTS OF THE SOLAR SYSTEM; OORT CLOUD The Oort Cloud is an immense spherically- shaped cloud surrounding our Solar System. The vast distance of the Oort cloud is considered to be the outer edge of the Solar System. A diagram comparing the size of the Oort Cloud to the orbits of Uranus and Pluto.
LUNAR ECLIPSE Penumbral Lunar Eclipse: The Moon passes through Earth's penumbral shadow. This type of eclipse is difficult to detect. Partial Lunar Eclipse: A portion of the Moon passes through Earth's umbral shadow. Total Lunar Eclipse: The entire Moon passes through Earth's umbral shadow.
SOLAR ECLIPSES A solar eclipse occurs when the moon passes in a direct line between the Earth and the Sun. The moon's shadow travels over the Earth's surface and blocks out the Sun's light as seen from Earth. Image courtesy of NASA
SOLAR ECLIPSE During a total solar eclipse the entire central portion of the Sun is blocked out. During a total solar eclipse, the Sun's outer atmosphere, the corona, is visible. Image Courtesy of NASA
SOLAR ECLIPSE If the penumbra passes over you, only part of the Sun's surface will be blocked out. You will see a partial solar eclipse, and the sky may dim slightly depending upon how much of the Sun's disc is covered. Partial Solar Eclipse
SOLAR ECLIPSE In some cases, the moon is far enough away in its orbit that the umbra never reaches the Earth at all. In this case, there is no region of totality, and what you see is an annular solar eclipse. In an annular eclipse, only a small, ring-like sliver of light of the Sun’s disk is visible. ("annular" means "of a ring"). Annular Eclipse Courtesy of NASA
PLANETARY PHASES Inferior Planets Explanation The planets, as viewed in the sky, exhibit characteristic aspects and phases. "Aspects" refers to the location of the planet with respect to our overhead sky reference;"phases" refers to the fact that the planets exhibit phases.
PLANETARY PHASES Superior Planets Explanation The aspects and phases of the superior planets differ from those of the inferior planets because of geometry: their orbits are outside that of the Earth.
PLANETARY PHASES Possible Comparison Activity
PLANETARY MOTIONS: ROTATION The time the Earth takes to make a complete rotation on its axis varies by about a millionth of a second per day. While some days are shorter than average, the planet’s rotation shows a long-term slowing trend, ultimately leading to a longer day.
PLANETARY MOTIONS: PRECESSION The Earth's rotational axis is not fixed in space. Like a rotating toy top, the direction of the rotation axis executes a slow precession with a period of 26,000 years.
PLANETARY MOTIONS: PRECESSION Pole Stars are transient. Thus, Polaris will not always be the Pole Star or North Star. Earth's rotation axis happens to be pointing almost exactly at Polaris now, but in 13,000 years the precession of the rotation axis will mean that the bright star Vega in the constellation Lyra will be approximately at the North Celestial Pole, while in 26,000 more years Polaris will once again be the Pole Star.
PLANETARY MOTIONS: PRECESSION (A BIT MORE INFORMATION) This precession causes Earth’s axis to describe a circle with a 23.5° radius relative to a fixed point in space over a period of about 26,000 years.
PLANETARY MOTIONS: PRECESSION Due to the precession of the equinoxes, the vernal equinox moves through all the constellations of the Zodiac over the 26,000 year precession period. Presently the vernal equinox is in the constellation Pisces and is slowly approaching Aquarius.
KEPLER’S FIRST LAW OF PLANETARY MOTION The orbit of a planet around the Sun is an ellipse with the Sun at one focus.
KEPLER’S SECOND LAW OF PLANETARY MOTION A line joining a planet and the sun sweeps out equal areas in equal intervals of time.
KEPLER’S THIRD LAW OF PLANETARY MOTION The square of the total time period (T) of the orbit is proportional to the cube of the average distance of the planet to the Sun (R). (The Law of Harmonies)
KEPLER’S THIRD LAW OF PLANETARY MOTION The major axis of an ellipse is a line drawn through both foci as illustrated in the graph to the left. However, we must find the semimajor axis.
KEPLER’S THIRD LAW OF PLANETARY MOTION Semi means half, so the major axis is cut in half as shown in the diagram. The mean distance of a planet from the Sun may be used as the number for the semimajor axis.
KEPLER’S THIRD LAW OF PLANETARY MOTION You may use the astronomical unit (AU) as the distance number for calculating the length of the year. The mean distance of the Earth from the Sun is 93,000,000 miles. This represents one astronomical unit, or AU for short.
KEPLER’S THIRD LAW OF PLANETARY MOTION The numbers work like this: 1 x 1 = 1 x 1 x 1 (1) 2 = (1) 3 For a planet 2 AU from the Sun, (This planet’s year) = 2 x 2 x 2 (This planet’s year) = 8 ^ 0.5 = 2.8 (Note: 0.5 is the exponent for square root rounds to 2.8)
KEPLER’S THIRD LAW OF PLANETARY MOTION Since a planet 1 AU from the Sun (Earth) has a year of 365 days, you must multiply that value by the value determined for a planet at 2 AU by Kepler’s Third Law or 2.8 to determine the number of Earth days required to orbit the Sun. 2.8 x 365 or 1022 days
KEPLER’S THIRD LAW OF PLANETARY MOTION: REPRESENTATIVE ACTIVITY Calculate the length of year for a planet located 4.5 AU from the Sun.
KEPLER’S THIRD LAW OF PLANETARY MOTION: REPRESENTATIVE ACTIVITY Calculate the length of year for a planet located 4.5 AU from the Sun. Using the simplified formula for Kepler’s Third Law: 1 x 1 = 1 x 1 x 1 Step 1: 1 x 1 = 4.5 x 4.5 x 4.5 Step 2: 1 x 1 = 4.5 x 3 = Step 3: ^ 0.5 = Step 4: 9.5 x 365 = days
KEPLER’S THIRD LAW OF PLANETARY MOTION Hopefully participants will be asked to calculate only the orbital period of a planet when given its distance from the Sun in AUs. Determining the distance in AUs from the Sun when its orbital period is known requires working with cube roots. Since participants have been asked to bring a calculator capable of determining square roots, they should not be asked to calculate the planet’s distance in AUs.
NEWTON’S FIRST LAW OF MOTION Every object in a state of uniform motion tends to remain in that state of motion unless an external force is applied to it. This law is recognized as Galileo's concept of inertia, and is often termed simply as the "Law of Inertia".
NEWTON’S SECOND LAW OF MOTION The relationship between an object's mass m, its acceleration a, and the applied force F is F = ma. Acceleration and force are vectors (as indicated by their symbols being displayed in slant bold font); in this law the direction of the force vector is the same as the direction of the acceleration vector. This is the most powerful of Newton's three Laws, because it allows quantitative calculations of dynamics: how do velocities change when forces are applied.
NEWTON’S THIRD LAW OF MOTION For every action there is an equal and opposite reaction. This law explains the flight of a rocket.
NEWTON’S THIRD LAW OF MOTION: THE LEGEND What Really Happened with the Apple? Newton, upon observing an apple fall from a tree, began to think along the following lines: The apple is accelerated, since its velocity changes from zero as it is hanging on the tree and moves toward the ground. Thus, by Newton's 2nd Law there must be a force that acts on the apple to cause this acceleration. Let's call this force "gravity", and the associated acceleration the "acceleration due to gravity." Imagine the apple tree is twice as high. Again, we expect the apple to be accelerated toward the ground, so this suggests that this force we call gravity reaches to the top of the tallest apple tree.
NEWTON’S LAW OF GRAVITATION Newton reasoned that if the force of gravity reaches to the top of the highest tree, might it not reach even further; In particular, might it not reach all the way to the orbit of the Moon!
NEWTON’S LAW OF GRAVITATION Then, the orbit of the Moon about the Earth could be a consequence of the gravitational force, because the acceleration due to gravity could change the velocity of the Moon in just such a way that it followed an orbit around the earth.
NEWTON’S LAW OF GRAVITATION This can be illustrated with the thought experiment shown in the figure to the left. Suppose we fire a cannon horizontally from a high mountain; the projectile will eventually fall to earth, as indicated by the shortest trajectory in the figure, because of the gravitational force directed toward the center of the Earth and the associated acceleration.
NEWTON’S LAW OF GRAVITATION But as we increase the muzzle velocity for our imaginary cannon, the projectile will travel further and further before returning to Earth. Finally, Newton reasoned that if the cannon projected the cannon ball with exactly the right velocity, the projectile would travel completely around the Earth, always falling in the gravitational field but never reaching the Earth, which is curving away at the same rate that the projectile falls.
NEWTON’S LAW OF GRAVITATION That is, the cannon ball would have been put into orbit around the Earth. Newton concluded that the orbit of the Moon was of exactly the same nature: the Moon continuously "fell" in its path around the Earth because of the accelera-tion due to gravity, thus producing its orbit.
NEWTON’S LAW OF GRAVITATION By such reasoning, Newton came to the conclusion that any two objects in the Universe exert gravitational attraction on each other, with the force having a universal form:
NEWTON’S LAW OF GRAVITATION The constant of proportionality G is known as the universal gravitational constant. “G” is termed a "universal constant" because it is thought to be the same at all places and all times, and thus universally characterizes the intrinsic strength of the gravitational force. To continue your studies, go to:
EFFECTS OF PLANETS AND THEIR SATEL- LITES UPON EACH OTHER: TIDAL LOCK Tidal locking occurs when the gravitational gradient makes one side of an astronomical body to always face another. A tidally locked body takes just as long to rotate around its own axis as it does to revolve around its partner. This synchronous rotation causes one hemisphere constantly to face the partner body.
EFFECTS OF PLANETS AND THEIR SATEL- LITES UPON EACH OTHER: TIDAL LOCK Usually, only the satellite becomes tidally locked around the larger planet. If the difference in mass between the two bodies and their physical separation is small, both may become tidally locked to the other. Pluto and Charon are tidally locked to each other.
TIDAL COUPLING & GRAVITATIONAL LOCKING As a consequence of tidal interactions with the Moon, the Earth is slowly decreasing its rotational period and eventually the Earth and Moon will have exactly the same rotational period, and these will also exactly equal the orbital period. Thus, billions of years from now the Earth will always keep the same face turned toward the Moon, just as the Moon already always keeps the same face turned toward the Earth.
Effects of Planets and Their Satellites upon each other: Shepherding Cordelia and Ophelia, a pair of shepherding satellites on each side of Epsilon ring of Uranus, keep the ring particles in place through resonant gravitational forces.
Effects of Planets and Their Satellites upon each other: Resonance Hyperion and Titan are in a 4:3 orbital resonance, which means that Titan orbits Saturn 3 times for every 4 times Hyperion orbits. As a result, Hyperion gets periodic "shoves" from Titan's gravity as their orbits match up.
Constellations Identification of the constellations containing all planets visible on the evening of the day of the competition, either with the unaided eye or a telescope.
REPRESENTATIVE ACTIVITY Participants will attempt to identify and to place in sequential order the series of events in the geologic history of one or more small areas on the surface of a planet or satellite.
REPRESENTATIVE ACTIVITY This is an imaginary scene on Earth’s Moon. Using the concept of super-position, list the events as they occurred, by letter and in order, from oldest to most recent.
REPRESENTATIVE ACTIVITY 1. B, A, C Event B is the oldest as it is overlapped by event A. Event C is the most recent because it overlaps Event A.
PART IV: RESOURCES THE SOLAR SYSTEM
RECOMMENDED INTERNET RESOURCES Solar System Exploration: arSys or arSyshttp://solarsystem.nasa.gov/planets/index.cfm World Book at NASA: From National Geographic system/ system/
RESOURCES The Game of SPACE Stars Planets Astronomy Constellations Exploration Newly revised in 2008 Visit:
RESOURCES d/sci_olympiad.html (or use key phrase “Science Olympiad Wright Center”) Science Olympiad Table of Contents Astronomy Biology and Chemistry Coaches Clinic Earth Science Physics/Problem Solving/Engineering Road Scholar
RESOURCES sa.gov/Images/StarChild/solar_system_level1/solar_system.gif& imgrefurl=http://starchild.gsfc.nasa.gov/docs/StarChild/solar_sy stem_level1/solar_system.html&h=288&w=284&sz=48&tbnid= KkNwQtetKFCm_M:&tbnh=110&tbnw=108&prev=/images%3 Fq%3Dsolar%2Bsystem&start=1&sa=X&oi=images&ct=image& cd=1 h_eclipse_anim_001225_02.gif partial solar eclipse h_eclipse_anim_001225_02.gif lunar eclipse solar system composite image
NATIONAL SCIENCE EDUCATION STANDARDS Earth and Space Science, Content Standard D: Structure of the Earth System; Earth’s History; Earth in the Solar System. Physical Science: Content Standard B: Motions and Forces; Transfer of Energy
Recommended Websites Astronomy 161: The Solar System Solar Physics: The Sun Kepler’s Laws