Universe 8/e Freedman

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CHAPTER 1 Astronomy and the Universe
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What we will learn

• How exploring other planets provides insight into
  the origins of the solar system and the nature of
  our Earth
• Stars have a life cyclethey form, evolve over
  millions or billions of years, and die
• Stars are grouped into galaxies, which are found
  throughout the universe

• How astronomers measure the positions and sizes
  of celestial objects
• How to express very large or very small numbers
  in convenient notation
• Why astronomers use different units to measure
  distances in space
• What astronomy can tell us about our place in the
  universe

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Astronomy, Science, and the Nature of the Universe
The universe is comprehensible. The scientific
method is a procedure for formulating hypotheses
about the universe. These are tested by
observation or experimentation in order to build
consistent models or theories that accurately
describe phenomena in nature
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Astronomy, Science, and the Nature of the Universe
Observations of the heavens have helped
scientists discover some of the fundamental laws
of physics. The laws of physics are in turn
used by astronomers to interpret their
observations.
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The Solar System
Exploration of the planets provides information
about the origin and evolution of the solar
system, as well as about the history and
resources of Earth.
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The Sun and Planets to Scale
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Stars Nebulae
Studying the stars and nebulae helps us learn
about the origin and history of the Sun and the
solar system.
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Galaxies
Observations of galaxies tell us about the origin
and history of the universe.
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Angular Measure
Astronomers use angles to denote the positions
and sizes of objects in the sky. The size of an
angle is measured in degrees, arcminutes, and
arcseconds.
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Small-Angle Formula
Note a has to be in arcseconds !!!
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Speed of Light c
 
c 300 000 000 m/s
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Powers-of-Ten Notation
This is a convenient shorthand system for writing
numbers. It allows very large and very small
numbers to be expressed in a compact form.
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Units of Distance

• Astronomers use a variety of distance units.
• These include
• astronomical unit or (the average distance from
  Earth to the Sun)
• light-year or ly (the distance that light travels
  in one year)
• parsec or pc

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Key Ideas

• Astronomy, Science, and the Nature of the
  Universe The universe is comprehensible. The
  scientific method is a procedure for formulating
  hypotheses about the universe. These are tested
  by observation or experimentation in order to
  build consistent models or theories that
  accurately describe phenomena in nature.
• Observations of the heavens have helped
  scientists discover some of the fundamental laws
  of physics. The laws of physics are in turn used
  by astronomers to interpret their observations.
• The Solar System Exploration of the planets
  provides information about the origin and
  evolution of the solar system, as well as about
  the history and resources of Earth.
• Stars and Nebulae Studying the stars and nebulae
  helps us learn about the origin and history of
  the Sun and the solar system.

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Key Ideas

• Galaxies Observations of galaxies tell us about
  the origin and history of the universe.
• Angular Measure Astronomers use angles to denote
  the positions and sizes of objects in the sky.
  The size of an angle is measured in degrees,
  arcminutes, and arcseconds.
• Powers-of-Ten Notation is a convenient shorthand
  system for writing numbers. It allows very large
  and very small numbers to be expressed in a
  compact form.
• Units of Distance Astronomers use a variety of
  distance units. These include the astronomical
  unit (the average distance from Earth to the
  Sun), the light-year (the distance that light
  travels in one year), and the parsec.