Astronomy 192-401

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Astronomy 192-401 Stars, Galaxies, and the
Universe Dr. Bruno deHarak
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A few questions

• Write 2,300 using scientific notation.
• 104
• 10
• 40
• 10,000
• 4,444,444,444
• How many days are in a year?
• If 3x 1 13 then x
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• 2
• 3
• None of the above
• What causes the seasons?
• What do you hope to learn in this class?

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Stars, Galaxies, and the Universe
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Stars, Galaxies, and the Universe
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Stars, Galaxies, and the Universe
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Syllabus
Instructor Dr. Bruno deHarak Office CP
56 Phone [phone] Email badeha2_at_uky.edu Webs
ite http//www.pa.uky.edu/bdeharak/ast192/home.
htm Office Hours Monday and Wednesday 5-6 PM,
and by appointment Textbook Stars, Galaxies,
and Cosmology, The Cosmic Perspective, Vol.
2 by Bennett, Donahue, Schneider, and Voit
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Announcement
There will be a substitute on Jan. 23, 28, 30 and
Feb. 4.
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Reading Assignment
Read Chapter 1 and review the Mathematical Skills
appendix. Ensure that you a) know the terms
listed in the blue box on page 4. b) know the
items listed in the Summary Of
Key Concepts. c) are comfortable working with
powers of 10s and scientific notation. Expect a
quiz on Monday (Jan. 14)!!
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Where are we?
Room 153 Chemistry-Physics Building
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Where are we?
Room 153 Chemistry-Physics Building University of
Kentucky
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Where are we?
Room 153 Chemistry-Physics Building University of
Kentucky Lexington Kentucky
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Where are we?
Room 153 Chemistry-Physics Building University of
Kentucky Lexington Kentucky USA
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Where are we?
Room 153 Chemistry-Physics Building University of
Kentucky Lexington Kentucky USA Earth
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Where are we?
Solar System 8 planets, 1 large star
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Where are we?
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Light-years
A light-year is a measure of distance (not time).
A light-year is the distance that light travels
in a year.
The speed of light is c 300,000 km/s (or
186,000 miles/s)
distance speed x time
1 ly speed x time
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Special theory of relativity
The speed of light, c, is the same for all
observers, no matter what their relative speeds.
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How far is a light-year?
distance speed x time
The speed of light is c 300,000 km/s (or
186,000 miles/s)
There are
1 ly 300,000 km/s x 31,536,000 s
9,500,000,000,000 km 9.5 x 1012 km
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Astronomy 192-401 Stars, Galaxies, and the
Universe