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Earth and Space • 1.4: Student knows that the planets differ in size, characteristics, and composition and that they orbit the sun in our solar system. • 1.5: Understands the arrangement of planets in our Solar System.
Overview of the Solar System • The solar system consists of: • the Sun, • the nine planets orbiting the Sun, • Possibility of a tenth planet, currently still under investigation by the Astronomical International Union (AIU) (as of July 05) • satellites of the planets, • asteroids, • comets, • and interplanetary medium1. • The Sun is the center of our solar system (Heliocentric Model). • developed by Nicolaus Copernicus, a Polish astronomer http://www.mnsu.edu/emuseum/information/solarsystem/solar_system.html
Understanding Earth and Space • Scientific Notation • Mass vs. Weight • Light Year as a unit of Measurement • Density and Volume • Rotation vs. Revolution • Chemical Composition of Planets • Physical Arrangement of Planets
Scientific Notation General Form: Where: N = number and x = exponent of 10. • Scientific Notation is based on powers of the base number 10. • The use of 10 digits for a numbering system may have arisen from counting to 10 using fingers, putting a mark in the sand and continuing to count to 10 again.
Why do we use Scientific Notation? • Scientific notation is a way to shorten very large numbers and extremely small ones for better understanding. • Numbers placed in this notation can be used in computations in a much easier manner. • This advantage was more practical before the invention of calculators and their abundance. How? In scientific notation; 2,890.0 becomes 2.89 x 103.
Scientific Notation Procedure Step 1: Move the decimal place until there is a number between 1 and 10. Step 2: Then add an exponent of ten that tells how many places the decimal place was moved. I can move the decimal in two ways: to the right or to the left, how do I differentiate them? • An exponent of ten with a positive exponent, such as 105, means the decimal was moved to the left. • An exponent of ten with a negative exponent, such as 10-5, means the decimal was moved to the right. • Let’s try it !!!
In scientific notation, 2,890 becomes 2.89 x 103. Remember that any whole number can be written with a decimal point. For example: 2,890 = 2,890.0 Now, move the decimal place until there is a number between 1 and 10. By moving the decimal point to the left in 2,890.0 you will get 2.89 Next, count how many places the decimal point was moved. The decimal had to be moved 3 places to the left in order to change 2,890.0 to 2.89 Therefore; 2,890.0 becomes 2.89 x 103 Let’s verify it! You can show that you moved the decimal 3 places to the left by multiplying the number by 103. 2.89 x 103= 2.89 x 10 x 10 x 10 2.89 x 103 = 2,890.0 Example of a very large number
In scientific notation, 0.0073 becomes 7.3 x 10-3. First, move the decimal place until there is a number between 1 and 10. If the decimal is moved to the right in 0.0073 you will get 7.3. Next, count how many places the decimal point was moved. By moving it three places to the right, 0.0073 changes to 7.3. Therefore; 0.0073 becomes 7.3 x 10-3 Let’s verify it! You can show that you moved the decimal point 3 places to the right by multiplying the number by 10-3. 7.3 x 10-3 = 7.3 ÷ 103 0.0073 becomes 7.3 x 10-3 Example of a very small number
Mass vs. Weight What is the difference between mass and weight? • Mass => measure of how much matter an object has. • Weight=> measure of how strongly gravity pulls on that matter.
Difference Between Mass and Weight • Weight is dependent on gravity. • Weight is the force exerted on mass by gravity. • Gravity is a force that pulls us toward the center of the planet, which keeps us from drifting off into space. • Every single object in the universe has gravity. • Weight will change depending on the surface gravity. • Mass is independentof gravity. • Mass is the amount (quantity) of matter in an object. • Mass has the same value everywhere in the universe.
Mass, Weight, and Gravity • If you find the weight of something on Earth and then take it to the Moon and weigh it again, you will find that it is lighter when it is on the Moon. • This is because the surface gravity is less on the Moon.
How to Calculate Your Weight in Other Planets • Calculate your weight by multiplying mass by the gravity on the surface of the planet. Weight=Mass x Surface Gravity Then surface gravity is the gravitational force exert on the surface.
How to Calculate Your Weight on Other Planets • So, if you know your weight on Earth and the surface gravity on Earth you can calculate your mass Mass = Weight on Earth Surface Gravity on Earth
Chart of Planets and Their Relative Surface Gravity Relative??? To what??? Relativemeans there is a comparison with a reference point, in this case, Earth.
Example Calculation Cristal weighs 100 lbs on Earth. How much would she weigh on Pluto? • First, calculate her mass on Earth: Mass = Weight on Earth Surface Gravity on Earth = 100lbs = 100 lbs 1 Relative surface gravity of Earth, as previously shown.
Cristal’s Weight on other Planets • After obtaining the mass, calculate the weight on the other planet using the relative surface gravity of Pluto: Weight=Mass x Relative Surface Gravity Weight = 100lbs x 0.06 = 6 lbs Cristal would weigh 6 pounds on Pluto!!!
Cristal’s Weight on Other Planets http://www.exploratorium.edu/ronh/weight/
What is a Light Year ? • A Light Year is a unit of distance. • It is defined as the distance that light can travel in a year. • Light moves at a velocity of about 300,000 km/sec or 300,000,000 m/sec • Light travels 9,500,000,000,000 km in one year, which is9.5 x 1012 km. • Eg:) (21,000,000,000,000,000,000 km) = 2.21053 *106 light years Ex.) The distance to the next nearest big galaxy, the Andromeda Galaxy, is 21 quintillion km. That's 21,000,000,000,000,000,000 km. This is a very large number and it is hard to write and to interpret. So astronomers use other units of distance.
DENSITY AND VOLUME Each box has the same volume. If each ball has the same mass, which box would weigh more? 1 2
Density and Volume The box that has more balls (box #1) has more mass per unit of volume. This property of matter is called density. What is density? • Density is how heavy something is for its size. • You can measure it by how much matter (mass) divided by how big it is (volume) Density = Mass Volume
Density Density = Mass Volume The density of a material helps to distinguish it from other materials. Since mass is usually expressed in grams and volume in cubic centimeters, density is expressed in grams/cubic centimeter. • The density of a material helps to distinguish it from other materials. Since mass is usually expressed in grams and volume in cubic centimeters, density is expressed in grams/cubic centimeter. g cm3 Units
Density Activities • Experiment of a floating egg • http://tiger.coe.missouri.edu/~pgermann/DiscEvent/Density/Floating_Egg/floating_egg.html • Insights • Why is it easier to float at the beach than at the pool? (Or salt.)
Rotation vs. Revolution • Earth makes a complete counterclockwise rotation (spins on its axis) once in each 24-hour period. This is why the sun appears to rise in the East and set in the West • The Earth revolves counterclockwise around the sun once every 365 1/4 days.
Size and Characteristics of Planets Classroom Questions: Which planet has the most mass? Which planet is the largest? Which planet is the most dense?
Composition of Planets • Magnetic Fields of Earth and other planets are believed to arise from electrical currents produced in the molten cores. • Chemical reaction of elements produces these electrical currents. 6 Planets Iron Nickel Alloy Core 3 Planets Rock and Ice Core Rocks and Materials Exhibition
Periodic Table of Elements Now we're getting to the heart and soul of the way your universe works.
Periodic Table • Periodic Table is a chart that scientists use to gather information about all the elements. • Elements are the building blocks of all matter. • Up to this point in time we have discovered over 100 elements. • While there may be more out there to discover, the basic elements remain the same. • Iron atoms found on Earth are identical to Iron atoms found on meteorites. The Iron atoms on Mars that make the soil red are the same too. • Information you can get from the periodic table for a specific element; • Mass, Number of electrons, protons and neutrons
Arrangementof Planets http://www.physics.hku.hk/~nature/CD/regular_e/lectures/chap06.html
Arrangementof Planets • Planets “orbit” around the sun • The exact arrangement of the planets depends on the day and time. • The planets move like this because of the gravitational pull of the Sun. Without this force, the planets would move off into space.
Orbits • The planets do not move in a perfect circle around the sun; the path is actually an ellipse Ellipse Circle
Orbits • A circle has a constant radius (the radius, r, does not change) • The radius of an ellipse is not constant (r1 ≠ r2) r2 r r1 Circle Ellipse
Ellipse • An ellipse can be described as a stretched circle with two center points. • The Sun is always at the center in an orbit's path • Not all ellipses have the same “shape”
Properties of Ellipses In terms of the diagram shown below, with "x" marking the location of the foci, we have the equation a + b = constant that defines the ellipse in terms of the distances a and b.
Properties of Ellipses The amount of "flattening" of the ellipse is termed the eccentricity. Eccentricity ranges from 0 to 1.
Pluto is Not Always the Ninth Planet! • Ever since 1930, school children have memorized the nine planets in order: Mercury, Venus, Earth, Mars, Jupiter Saturn, Uranus, Neptune, and PIuto. • But between January, 1979 and March, 1999, that order is not correct. Pluto's eccentric (ellipse-shaped) orbit brought it inside the orbit of Neptune, making it the eighth planet for two decades.
A Tenth planet?? • On July 29, 2005, Mike Brown (Cal Tech), made the announcement that his group discovered a tenth planet of the solar system. • Temporary name of this object: 2003UB313 • The International Astronomical Union (AIU), responsible for classifying planets, has yet to classify 2003UB313 as the tenth planet.
The Elliptical Orbit Concept • Before Copernicus's time (1473-1542 ), it was believed that we lived in a universe in which the earth was stationary and motionless at the center of several concentric, rotating spheres. • Copernicus theorized that planets revolve around the sun (the heliocentric model) • This theory was considered heresy • Kepler (1571-1630),was a “Copernican” who brought acceptance to the heliocentric concept through three planetary motion laws.
1: The Law of Ellipses • All planets move in elliptical orbits, with the sun at one focus.
2: The Law of Equal Areas • The line joining the planet to the Sun sweeps out equal areas in equal times as the planet travels around the ellipse.
Kepler’s Laws2: The Law of Equal Areas • The orbiting planet will speed up when it gets closer to the object at the focus. This is caused by the increased effect of gravity on the orbiting object as it gets closer to what it is orbiting around.
Kepler’s Laws 3: The Law of Harmonies This law shows the relationship for the time required for a planet to move around the Sun and the average distance from the Sun.