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Astronomy 101 The Solar System Tuesday, Thursday Tom Burbine [email protected] Course • Course Website: – http://blogs.umass.edu/astron101-tburbine/ • Textbook: – Pathways to Astronomy (2nd Edition) by Stephen Schneider and Thomas Arny. • You also will need a calculator. HW #3 • On Spark under Assessments: • Due Date: February 2, 2010 1:00 PM Metric System • 1 kilometer = 1,000 meters • 1 meter = 100 centimeters • 1 centimeter = 10 millimeters Scientific Notation • • • • • • 10000 = 104 100000000 = 108 10000000000 = 1010 100000000000000000000 = 1020 0.001 = 10-3 0.0000001 = 10-7 How do you write numbers? • • • • 31700000 = 3.17 x 107 2770000 = 2.77 x 106 0.00056 = 5.6 x 10-4 0.0000078 = 7.8 x 10-6 How do you do multiply? • 106 x 108 = 10(6+8) = 1014 • 10-5 x 103 = 10(-5+3) = 10-2 • (3 x 104 ) x (4 x 105) = 12 x 10(4+5) = 12 x 109 = 1.2 x 1010 How do you divide? • 108/106 = 10(8-6) = 102 • 10-6/10-4 = 10(-6-(-4)) = 10-2 • (3 x 108)/(4 x 103) = ¾ x 10(8-3) = 0.75 x 105 = 7.5 x 104 How many stars in the Universe • Say there are 100 billion galaxies • Each galaxy has 100 billion stars • So how many stars in the universe Answer • Number of stars in universe • = (100 x 109) x (100 x 109) = 10000 x 1018 = 1 x 1022 = 10,000,000,000,000,000,000,000 • This is about the same number of grains of sand in every beach in the world Questions: • How many of these 1022 stars have planets? • How many of these planets have life? • • • • • • • • • My - Mercury Very - Venus Eager - Earth Mother - Mars Just - Jupiter Served - Saturn Us -Uranus Nine -Neptune Pizzas - Pluto Does anyone play basketball? Assume • • • • • That the sun is the same size as a basketball Basketball diameter = 24.4 cm Sun Diameter = 1.4 x 109 m = 1.4 x 1011 cm Scale Factor = 1.74 x 10-10 Multiply scale factor by actual diameters of planets to get their approximate size Mercury • Diameter = 4.88 x 106 m • Multiply by scale factor (1.74 x 10-10) • Relative Diameter = 8.5 x 10-4 m = 0.85 mm Venus • Diameter = 1.21 x 107 m • Multiply by scale factor (1.74 x 10-10) • Relative Diameter = 2.1 x 10-3 m = 2.1 mm Earth • Diameter = 1.28 x 107 m • Multiply by scale factor (1.74 x 10-10) • Relative Diameter = 2.2 x 10-3 m = 2.2 mm Mars • Diameter = 6.80 x 106 m • Multiply by scale factor (1.74 x 10-10) • Relative Diameter = 1.2 x 10-3 m = 1.2 mm Jupiter • Diameter = 1.43 x 108 m • Multiply by scale factor (1.74 x 10-10) • Relative Diameter = 2.5 x 10-2 m = 25 mm = 2.5 cm Saturn • Diameter = 1.21 x 108 m • Multiply by scale factor (1.74 x 10-10) • Relative Diameter = 2.1 x 10-2 m = 21 mm = 2.1 cm Uranus • Diameter = 5.18 x 107 m • Multiply by scale factor (1.74 x 10-10) • Relative Diameter = 9.0 x 10-3 m = 9 mm Neptune • Diameter = 4.95 x 107 m • Multiply by scale factor (1.74 x 10-10) • Relative Diameter = 8.5 x 10-3 m = 8.5 mm Pluto • Diameter = 2.30 x 106 m • Multiply by scale factor (1.74 x 10-10) • Relative Diameter = 4.0 x 10-4 m = 0.4 mm What if we want to use the same scale factor to make a model of the solar system? • What’s the problem? How far away is Pluto? • Pluto is 5.9 x 1012 m from Sun on average • Multiply by scale factor (1.74 x 10-10) • Relative Distance from Sun = 1027 m = 1.027 km Seasons • http://www.learner.org/resources/series28.html Phases of the Moon29.53 day cycle http://en.wikipedia.org/wiki/File:Lunar-Phase-Diagram.png Eclipses Moon is tilted at an angle of 5 degrees to Earth’s orbit • http://astronomyonline.org/SolarSystem/LunarEcl ipse.asp Color of lunar eclipse • The Moon does not completely disappear because of the refraction of sunlight by the Earth’s atmosphere • If the Earth had no atmosphere, the Moon would be completely dark during an eclipse. • The red color arises because sunlight reaching the Moon must pass through the Earth’s atmosphere, where it is scattered. • Shorter wavelengths are more likely to be scattered by the small particles. By the time the light has passed through the atmosphere, the longer wavelengths dominate. This resulting light reflected from the Moon we perceive as red. Solar eclipse http://en.wikipedia.org/wiki/Image:Solar_eclips_1999_4_NR.jpg • Solar eclipses occur approximately every 18 months • However, they recur (on average) at any given place only once every 370 years • Moon's umbra moves eastward at over 1,700 km/hr • Every year, there are at least two lunar eclipses. • Can be viewed anywhere on the night side of the Earth http://home.cogeco.ca/~astrosarnia/Photos/Lunar%20eclipse%20binocular.jpg Solar eclipse of July 22, 2009 • Lasted a maximum of 6 minutes and 39 seconds off the coast of Southeast Asia http://upload.wikimedia.org/wikipedia/commons/f/f2/Solar_eclipse_animate_%282009-Jul-22%29.gif http://en.wikipedia.org/wiki/File:Solar_eclipse_22_July_2009_taken_by_Lutfar_Rahman_Nirjhar_from_Bangladesh.jpg Any Questions?