1. CHAPTER 1 Astronomy and the Universe CHAPTER 1 Astronomy and the Universe

3. 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 cycle—they 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

4. 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

5. 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. Astronomy, Science, and the Nature of the Universe

7. 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. The Solar System

10. The Sun and Planets to Scale

11. Studying the stars and nebulae helps us learn about the origin and history of the Sun and the solar system. Stars & Nebulae

16. Observations of galaxies tell us about the origin and history of the universe. Galaxies

19. 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. Angular Measure

24. Small-Angle Formula Note: “α” has to be in arcseconds !!!

25. Speed of Light “c” c = 300 000 000 m/s

26. This is a convenient shorthand system for writing numbers. It allows very large and very small numbers to be expressed in a compact form. Powers-of-Ten Notation

29. 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 Units of Distance

31. 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.

32. 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. Key Ideas