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Transcript
How big is our Solar System? SOLAR SYSTEM SCALING ACTIVITY To REALLY help you visualize how BIG it is, let’s make a scale model of our solar system • We need to know the actual distances of each planet’s orbit from the sun • We need to know the actual size of each planet • Then we’ll determine a scale factor that will allow us to create the biggest possible scale model in our immediate locale Where and how will we create our scale solar system? • Start at the corner of Jefferson and Sanger and walk east past the Freshman HS and the HMS Central Office Building • Measure distances in meters with meter tapes • Leave a marker at each location What’s next? So, how do we know how far to walk and how big each planet/body should be? How far is it to the Central Office building? Create a table Planet /Body Mercury Actual distance (km) 58,000,000 Venus 108,000,000 Earth 150,000,000 Mars 228,000,000 Asteroid belt Jupiter 780,000,000 Saturn 1,427,000,000 Uranus 2,900,000,000 Neptune 4,500,000,000 Pluto 5,900,000,000 Scaled Distance Scale size distance from last of planet (m) planet (m) (mm) Let’s try some out—DON’T fill out your table until instructed to do so! NOTE: NEITHER PLANET SIZES NOR DISTANCES BETWEEN ARE TO SCALE! Asteroid Belt Here’s the info you need for the asteroid belt: Distance from sun to the middle of the asteroid belt is 404,000,000 km For our scale, it will be located at 22.1 meters. The biggest asteroid, Ceres, is way too small at 914 km (568 miles) to show in this activity, so leave the actual size and scaled size of the PLANET/BODY blank. The total mass of all the asteroids is only 4% of the Moon’s mass! Completed table Planet /Body Mercury Actual distance (km) Scaled Distance Scale size distance from last of planet (m) planet (m) (mm) 58,000,000 2.91 Venus 108,000,000 5.43 2.52 0.6 celery seed Earth 150,000,000 7.51 2.08 0.6 celery seed Mars 228,000,000 11.4 3.89 Asteroid belt 404,000,000 22.1 10.7 Jupiter 780,000,000 39.0 16.9 7.1 big pea Saturn 1,427,000,000 71.6 32.6 5.8 small pea Uranus 2,900,000,000 144 72.4 2.3 peppercorn Neptune Pluto 4,500,000,000 5,900,000,000 -- 226 82.0 297 71.0 0.2 teeny dot 0.3 dot 2.2 peppercorn 0.1 teeny dot Origin of the Solar System • About 4.5 billion years ago, there was a rotating cloud of dust and gas (mostly hydrogen) quietly hanging about in our neighborhood of the galaxy. This cloud was a nebula. • At the center of the rotating nebula, material drew together because of gravity, and our Sun was born. The rest of the dust and gas settled into a disk surrounding the sun. • Something disturbed this nebula and caused it to start clumping together. •Planetesimals are small, irregularly shaped bodies formed by colliding matter. •As time went on, the planetesimals collided with each other, forming larger bodies. How can the Planets be Grouped? 1 AU = 1 astronomical unit = 1.50 x 108 km = distance from Earth to the sun Terrestrial Planets • Mercury • Venus • Earth • Mars All of these planets are small and rocky. They are MUCH smaller than the Jovian planets. Their densities are about 5 times that of water due to their chemical makeups of metals and solid minerals. Jovian Planets • Jupiter • Saturn • Uranus • Neptune All of these planets are gas giants. They are mostly composed of gases such as hydrogen, helium and methane and ices of water and ammonia. (Saturn would float on liquid water!) They also rotate MUCH faster than the terrestrial planets do. Planetary Composition, Distance from the Sun, and Melting Point Asteroid Belt • Between the Terrestrial and Jovian planets is the ASTEROID BELT. Asteroids are small rocky bodies that range in size from a dust particle to a few hundred kilometers. • Ceres is the largest and classified as a dwarf planet at 950 km in diameter. Comets Halley’s Comets are small bodies made of rocky and metallic pieces held together by frozen gases. A common name is “dirty snowball.” Comets generally revolve about the sun in elongated elliptical orbits. For most of its life, a comet remains frozen, but as it approaches the sun, the frozen gases begin to vaporize. The coma is the fuzzy, gaseous component of a comet’s head. A small glowing nucleus with a diameter of only a few km can sometimes be detected within a coma. As comets approach the sun most develop tails that extend for millions of km. Dust Tail and Gas Tail The streams of dust and gas each form their own distinct tail, pointing in slightly different directions. • The dust tail often forms a curved tail called the antitail. • The gas tail always points directly away from the Sun, as the ionized gas is more strongly affected by the solar wind than is dust. Comet McNaught, 2007 Jan. 20, Australia Jan. ?, Chile Jan. 11, Los Alamos Jan. 13, Germany Comet Sources in the Outer Solar System Kuiper Belt Outside the orbit of Neptune is the Kuiper Belt. Most comets from this region have short period, nearly circular orbits that lie roughly in the same plane as the planets. Oort Cloud Comets with long orbital periods appear to be distributed in all directions from the sun, forming a spherical shell around the solar system called the Oort Cloud. Meteoroids A meteoroid is a small, solid particle that travels through space. A meteor is the luminous phenomenon observed when a meteoroid enters Earth’s atmosphere and burns up, popularly called a shooting star. A meteorite is any portion of a meteoroid that reaches Earth’s surface. Meteoroids Most meteoroids come from any one of the following three sources: (1) Interplanetary debris left over from the formation of the solar system, (2) Material from the asteroid belt, or (3) The solid remains of comets that once traveled near Earth’s orbit. • Most repeating meteor showers are associated with debris left by a comet. • Each year, as Earth crosses the path of the comet, pieces of debris are swept up by Earth’s gravity and burn up in the atmosphere. Meteorites • Meteorites are classified into three major types: stony (94%), iron (5%), and stonyiron (1%).