Book contents
- Frontmatter
- Contents
- Preface
- Acknowledgments
- Part I Introducing steps to astronomy
- Part II The Solar System
- Part III Introducing stars
- Part IV Introducing galaxies and the Universe
- Epilog
- Appendix I The small-angle formula
- Appendix II Exponential notation
- Appendix III The Solar System
- Appendix IV The closest and brightest stars
- Appendix V Physical and astronomical constants
- Appendix VI Conversion factors
- Appendix VII Constellation maps
- Glossary
- Figure Credits
- Index
- Plate section
Part IV - Introducing galaxies and the Universe
Published online by Cambridge University Press: 05 February 2013
- Frontmatter
- Contents
- Preface
- Acknowledgments
- Part I Introducing steps to astronomy
- Part II The Solar System
- Part III Introducing stars
- Part IV Introducing galaxies and the Universe
- Epilog
- Appendix I The small-angle formula
- Appendix II Exponential notation
- Appendix III The Solar System
- Appendix IV The closest and brightest stars
- Appendix V Physical and astronomical constants
- Appendix VI Conversion factors
- Appendix VII Constellation maps
- Glossary
- Figure Credits
- Index
- Plate section
Summary
Introducing galaxies and the Universe
So far we have surveyed what might be called our corner of the cosmos: a region of space extending outward several thousand light years. We now extend our vision much farther – to the very edge of the known Universe. In doing so we will find a new and previously unsuspected structure: galaxies. Everything we have so far studied – the Earth, the Sun and all the Solar System; the stars visible to the naked eye and the more distant stars that telescopes reveal; interstellar clouds – all these are part of an enormous structure known as the Milky Way Galaxy. Lying beyond our Galaxy lie other galaxies, billions and billions of them, stretching out to the farthest bounds of the Universe.
It is difficult to comprehend the immensity of the distances we are about to encounter. A ray of light, which can cross the Atlantic Ocean in 0.02 seconds, would require a hundred thousand years to cross our Galaxy. Even the nearby galaxies lie millions of light years from us. Light from a distant galaxy began its journey toward us long before the Earth was formed.
- Type
- Chapter
- Information
- Understanding the UniverseAn Inquiry Approach to Astronomy and the Nature of Scientific Research, pp. 449 - 452Publisher: Cambridge University PressPrint publication year: 2013