A brief conceptual history of cometary science
Abstract
The history of cometary astronomy can be naturally divided into five major periods, with each transition marked by an important new insight. Before 1600, comets were usually viewed as heavenly omens, or possibly meteorological phenomena in the terrestrial atmosphere, and were not yet clearly established as astronomical bodies. Then followed two centuries of mostly positional measurements triggered by the stunning discovery of the universal law of gravitational attraction. Two highlights from this period, which lasted until the early nineteenth century, were the successful prediction of the March 1759 return of 1P/Halley's comet and the discovery of the nongravitational motion of Comet 2P/Encke. The era of cometary physics began with the passage of 1P/Halley in 1835, when spatial structures in a comet were described in detail for the first time. The year 1950 marked the emergence of the modern picture of comets as an ensemble of solar system objects composed of primordial ice and dust, generally on longperiod orbits and shaped by their interactions with the solar radiation field and the solar wind. Finally, the space missions to Comet 21P/Giacobini-Zinner in 1985, and especially to 1P/Halley in 1986, provided the first in situ measurements and the first images of a cometary nucleus. While these in situ observations significantly improved our understanding of cometary phenomena, they also posed many new questions for which we are still seeking answers. In this introductory chapter, we only briefly discuss the pre-modern observations of cometary phenomena, which are already well described in the monograph by Yeomans (1991), and focus instead on the advances in cometary science during the past 65 years or so, especially on the developments since the publication of the Comets book in 1982.
- Publication:
-
Comets II
- Pub Date:
- 2004
- Bibcode:
- 2004come.book....3F