Book contents
- Frontmatter
- Contents
- List of Tables
- Preface
- 1 Introduction
- 2 Dynamics
- 3 Solar Heating and Energy Transport
- 4 Planetary Atmospheres
- 5 Planetary Surfaces
- 6 Planetary Interiors
- 7 Magnetic Fields and Plasmas
- 8 Meteorites
- 9 Minor Planets
- 10 Comets
- 11 Planetary Rings
- 12 Extrasolar Planets
- 13 Planet Formation
- Appendix A List of Symbols Used
- Appendix B Acronyms Used
- Appendix C Units and Constants
- Appendix D Periodic Table of Elements
- Appendix E Observing Techniques
- Appendix F Interplanetary Spacecraft
- Appendix G Recent Planetary Images
- References
- Index
- Plate section
10 - Comets
- Frontmatter
- Contents
- List of Tables
- Preface
- 1 Introduction
- 2 Dynamics
- 3 Solar Heating and Energy Transport
- 4 Planetary Atmospheres
- 5 Planetary Surfaces
- 6 Planetary Interiors
- 7 Magnetic Fields and Plasmas
- 8 Meteorites
- 9 Minor Planets
- 10 Comets
- 11 Planetary Rings
- 12 Extrasolar Planets
- 13 Planet Formation
- Appendix A List of Symbols Used
- Appendix B Acronyms Used
- Appendix C Units and Constants
- Appendix D Periodic Table of Elements
- Appendix E Observing Techniques
- Appendix F Interplanetary Spacecraft
- Appendix G Recent Planetary Images
- References
- Index
- Plate section
Summary
You see therefore an agreement of all the Elements in these three, which would be next to a miracle if they were three different Comets … Wherefore, if according to what we have already said it should return again about the year 1758, candid posterity will not refuse to acknowledge that this was first discovered by an Englishman.
Edmond Halley, 1752, Astronomical Tables, LondonThe generally unexpected and sometimes spectacular appearances of comets have triggered the interest of many people throughout history. A bright comet can easily be seen with the naked eye, and its tail can extend more than 45° on the sky (Fig. 10.1). The name comet is derived from the Greek word κωμητηζ which means ‘the hairy one’, describing a comet's most prominent feature: its long tail. The earliest records of comets date back to ∼6000 bce in China. In the time of Pythagoras (550 bce) comets were considered to be wandering planets, but Aristotle (330 bce) and subsequent natural philosophers thought comets were some kind of atmospheric phenomenon. Comets were therefore scary, and often considered bad omens. An apparition of Comet 1P/Halley is depicted on the Bayeux Tapestry (Fig. 10.2), which commemorates the Norman conquest of England in 1066.
The first detailed scientific observations of comets were made by Tycho Brahe in 1577. Brahe determined that the parallax of the bright comet C/1577 VI was smaller than 15 arcminutes, and concluded that therefore the comet must be farther away than the Moon.
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- Information
- Planetary Sciences , pp. 405 - 447Publisher: Cambridge University PressPrint publication year: 2010