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Discover the fascinating world of astronomy and its impact on our daily lives. Challenge your thinking with mind-blowing ideas and explore the future of the universe. This preview chapter gives an overview of celestial bodies, scientific methods, and the concept of astronomical distance scales.
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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!!!!
