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Size and Scale Attendance Quiz II

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Size and Scale Attendance Quiz II Are you here today? Here! (a) yes (b) no (c) are we still here? Today’s Topics • “How do we know?” exercise • Size and Scale • What is the Universe made of? • How big are these things? • How do they compare to each other? • How can we organize objects to make sense of them? What is the Universe made of? Stars • Stars make up the vast majority of the visible mass of the Universe • A star is a large, glowing ball of gas that generates heat and light through nuclear fusion • Our Sun is a star Planets • According to the IAU, a planet is an object that 1. orbits a star 2. has sufficient self-gravity to make it round 3. has a mass below the minimum mass to trigger nuclear fusion 4. has cleared the neighborhood around its orbit • A dwarf planet (such as Pluto) fulfills all these definitions except 4 • Planets shine by reflected light • Planets may be rocky, icy, or gaseous in composition. Moons, Asteroids, and Comets • Moons (or satellites) are objects that orbit a planet • An asteroid is a relatively small and rocky object that orbits a star • A comet is a relatively small and icy object that orbits a star Solar (Star) System • A solar (star) system consists of a star and all the material that orbits it, including its planets and their moons Star Clusters • Most stars are found in clusters; there are two main types • Open clusters consist of a few thousand stars and are young (1-10 million years old) • Globular clusters are denser collections of 10s-100s of thousand stars, and are older (10-14 billion years old) Nebula • A nebula is an interstellar cloud of gas and/or dust • Nebulae are where stars are born and are also created when they die Galaxy • A galaxy is a great island of stars in space, all held together by gravity and orbiting a common center • In addition, there is gas and dust between the stars, some in the form of visible nebulae Cluster of Galaxies • A collection of galaxies all held together by gravity Universe • The Universe is the name for the sum total of all matter and energy; that is, everything within and between all galaxies How big are these things? Object Size (km) Moons, asteroids, comets 1-1,000 (100-103) Planets 1,000-100,000 (103-105); Earth ≈ 104 Stars (middle-aged) 100,000-10,000,000 (105-107); Sun ≈ 106 Stars (extreme) 10 (101) - neutron stars 1,000,000,000 (109) - red giants Solar (Star) System 10,000,000,000 (1010) Stellar Clusters 100,000,000,000,000 (1014) - open clusters 1,000,000,000,000,000 (1015) - globular clusters Nebulae 1,000,000,000,000-1,000,000,000,000,000 (1012-1015) Galaxies 1,000,000,000,000,000,000 (1018) Clusters of Galaxies 100,000,000,000,000,000,000 (1020) Universe ? Scientific Notation • In order to write these very big numbers, it is convenient to use a shorthand known as Scientific Notation • A number such as 100 can be written as 102, where the 2 in the exponent means multiply 10 two times, i.e, 100=10x10 • Likewise, 10,000 = 104 and 100,000,000,000 = 1011 and so on • To multiply two such numbers, we simply add the exponents; to divide we subract the exponent in the denominator from the exponent in the numerator 103 x 107 = 10(3+7) = 1010 109 / 104 = 10(9-4) = 105 • Thus, to figure out how many times larger than the Solar System is the Milky Way: 1018 km / 1010 km = 108; thus, the Milky Way is 100 million times larger than the Solar System Astronomical measures of distance • Since astronomical distances are so large, it is convenient to define some other measures of size and distance 1 astronomical unit (AU) = the average distance from the Earth to the Sun = 150,000,000 km = 1.5 × 108 km 1light - year = (speed of light) × (1 year) ⎛ km⎞ ⎛ 365 days 24 hr 60 min 60 s ⎞ = ⎜ 300,000 ⎟ ×⎜ × × × ⎟ ⎝ s ⎠ ⎝ 1 yr 1 day 1 hr 1 min⎠ How far is a light-year? 1 light-year = (speed of light) × (1 year) ⎛ km⎞ ⎛ 365 days 24 hr 60 min 60 s ⎞ =⎜ 300,000 ⎟ × × × × ⎝ s ⎠ ⎝⎜ 1 yr 1 day 1 hr 1 min⎠⎟ =9,460,000,000,000 km ≈ 10,000,000,000,000 km ≈ 1013 km ≈ 105 AU How big are these things? Object Size (km, AU, or light years) Moons, asteroids, comets 1-1,000 (100-103) km Planets 1,000-100,000 (103-105) km; Earth ≈ 104 km Stars (middle-aged) 100,000-10,000,000 (105-107) km; Sun ≈ 106 km Stars (extreme) 10 (101) km - neutron stars 1,000,000,000 (109) km or 10 AU - red giants Solar (Star) System 100 AU Stellar Clusters 30 light years - open clusters 30-150 light years - globular clusters Nebulae 0.1-100 light years (ly) Galaxies 100,000 light years (ly) Clusters of Galaxies 10 million light years (Mly) Universe ? How big are these different sizes? What is our place in the universe? https://youtu.be/17jymDn0W6U Organizing Things What is the correct order from smallest to largest, of the following objects? Tree, Continent, Chloroplast, Forest, Earth, Leaf (a) Earth, Continent, Tree, Forest, Leaf, Chloroplast (b) Earth, Continent, Forest, Tree, Leaf, Chloroplast (c) Chloroplast, Leaf, Tree, Forest, Continent, Earth (d) Leaf, Tree, Chloroplast, Forest, Continent, Earth (e) Leaf, Chloroplast, Tree, Forest, Continent, Earth How can we organize astronomical objects? • Smaller objects often orbit larger objects (planets, asteroids, comets orbit stars; moons orbit planets) • Some things are contained within other objects 1. Stars, planets, asteroids, comets are part of solar (star) systems) 2. Stars are part of stellar clusters 3. Stars and stellar clusters form from nebulae 4. Stars, solar (star) systems, stellar clusters, nebulae are part of galaxies 5. Galaxies are part of galaxy clusters 6. Everything is part of the Universe • Most types of objects come in a range of sizes In-class group activities • Important to remember when doing in-class activities 1. Work as a group. Each of you should have agreed to answer and written it down, with explanations, before moving on. Don’t let your group move ahead until you understand each part! 2. Get right to work! You typically have 10-15 minutes to complete these activities. That is plenty of time, if you start right in. 3. These activities are your textbook - write good clear explanations for all your answers. You will be grateful you did later. • Get into your groups of 3-4 • Complete the two ranking tasks (10 minutes) 1. Size & Scale - Exercise #1 2. Size & Scale - Exercise #2 Pluto v. the Moon Ordering by Size What is the correct order from smallest to largest, of the following objects? Andromeda Galaxy, Jupiter, Galaxy Cluster, Asteroid, Sun, Solar System (a) Jupiter, Asteroid, Sun, Solar System, Andromeda Galaxy, Galaxy Cluster (b) Asteroid, Jupiter, Sun, Solar System, Andromeda Galaxy, Galaxy Cluster (c) Asteroid, Jupiter, Solar System, Sun, Andromeda Galaxy, Galaxy Cluster (d) Asteroid, Sun, Jupiter, Solar System, Andromeda Galaxy, Galaxy Cluster (e) Asteroid, Jupiter, Sun, Andromeda Galaxy, Galaxy Cluster, Solar System.
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