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What do the following have in common?. Why Bother???. Exciting subject filled with new discoveries! Affects our every day lives! Mind blowing ideas that challenge our way of thinking! The wave of the future!. Preview Chapter. The Cosmic Landscape. A Few Definitions.
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Why Bother??? • Exciting subject filled with new discoveries! • Affects our every day lives! • Mind blowing ideas that challenge our way of thinking! • The wave of the future!
Preview Chapter The Cosmic Landscape
A Few Definitions • moon or satellite: a body orbiting a planet.
A Few Definitions • planet: a celestial body that is in orbit around the sun, has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a ... nearly round shape, and has cleared the neighborhood around its orbit.
A Few Definitions • star: a massive gaseous body held together by • gravity and generally emitting light by nuclear • reactions.
A Few Definitions • solar-system: A collection of celestial objects (e.g. planets, comets, asteroids) orbiting around a common star.
A Few Definitions • galaxy: A collection of stars, gas, dust, and dark matter held together by their mutual • gravity.
A Few Definitions • Universe: Consists of everything around us Includes Everything!
Concept Question Which one of the following is listed in the correct order from smallest to largest in size? A) star, planet, solar-system, galaxy, Universe B) planet, star, solar-system, Universe, galaxy C) star, planet, galaxy, solar-system, Universe D) planet, star, solar-system, galaxy, Universe
Scientific Method • observe • hypothesize • test • modify,reject,or theorize
Astrology or Astronomy? • Uses the positions of planets to predict human behavior • Is a branch of Physics • Uses the scientific method to interpret observations • Is considered a pseudoscience • A detailed study of all the celestial bodies in the Universe, including planets, moons, stars, galaxies, etc. • Associates the signs of the zodiac with personality traits
1.0= 1.0 X 100 (100) 100.0= 1.0 X 102 (102) 1,000.0= 1.0 X 103 (103) 10,000.0= 1.0 X 104 (104) 100,000.00= 1.0 X 105 (1005) 0.1= 1.0 X 10-1 (10-1) 0.01= 1.0 X 10-2 (10-2) 0.001= 1.0 X 10-3 (10-3) 0.0001= 1.0 X 10-4 (10-4) 0.00001= 1.0 X 10-5 (10-5) Scientific Notation • express very small or very • large numbers in powers of ten • Format: . X 10
Scientific Notation Examples: Average Distance from the Earth to the Sun: 149,600,000.0 km 1.496 X 108 km Mass of ant: 0.004 g 4 X10-3 g
Concept Question Write -0.00000315 in scientific notation A) 3.15 X 10-6 B) 3.15 X 106 C) -3.15 X106 D) -3.15 X 10-6
Concept Question Write 7.89 X 10-6 in regular format A) 000007.89 B) 0.00000789 C) 7890000 D) 0.0000789
more practical to use Astronomical Units Average Distance from the Earth to the Sun Astronomical Unit 1 A.U. = 1.5 X 108 km Distance that light travels in a year Light Year speed of light in a vacuum: c = 3 x105 km/s (186,000 mi/s) so one light second: 3x105 km and one light year: 9.46x1012 km
here on Earth 55 light years away 70 years old 15 years old 70 years old 68 light years away 2 years old Looking Backwards in Time on a planet orbitting a distant star Because of the finite speed of light, we are able to look backwards in time!!!
Astronomical Distance Scales are Astronomical! The Moon: 1.3 light seconds away Alpha Centauri: 4.2 light years away The Sun: 8.3 light minutes away Andromeda Galaxy: 2.4 million light years away Galaxies in the Hubble Deep Field: as far as billions of light years away The finite speed of light gives us a fossil record of the history of the Universe!!!!
