I'm a big fan of the late great scientist/astronomer Carl Sagan. I've read most of his books and most are 5 stars...see my reviews.As a 40 year amateur astronomer I found Comet by Carl Sagan and Ann Druyan done fantastically well. Carl was always great at explaining a complex subject for the non scientist and keeping a complex subject interesting and allowing the reader to want to continue reading.
Comet has loads of beautiful pictures, drawings, and diagrams by very good artists especially my favorite Jon Lomberg (I bought a lithograph from him "First Baby on Mars"...absolutely wonderful). Back to Comet!
Carl Sagan and Ann Druyan give a great 1/3 of the book to the history of what mankind thought comets were, from evil things that foretold famine, death for armies, earthquakes and any number of disasters, to gradually a more modern "dirty ice ball" approach.
Then we learn the composition of comets. Some rich in organic matter with ices of methane, ammonia, carbon dioxide and mostly regular water ice plus some heavy water isotopes and a little silicates and metals. A huge "dirty iceball".
We see the near comets with orbits starting beyond Jupiter to comets way way out in the far reaches of the Oort cloud where orbits around the sun may take 10 million years. We see the different "ices" that boil off at different spacings from the sun, with regular water ice being the last to go as comets get closer to the sun. We learn about comet comas, their tails and their nucleus heads.
We learn some asteroids may be worn out comets as each time comets get close enough to the sun they slowly "die" as a meter or so of ice is boiled off until rocky silicates, and heavy metals like iron are left.
We see the various extinction ages where most of the species on Earth were eliminated with comets crashing into the Earth as main contributors. We see about 69 million years ago, the extinction of the dinosaurs possibly by a comet impact, allowing mammals to evolve with no competition from the dinosaurs, allowing the evolution of man.
Lots of history about many famous and not so famous scientists and ancient theorists, and how different religions from different countries perceived comets. Lots of theories on comet formation, where they come from, how many there are, and where they are now. Are we in danger of getting hit by one now! Explanation of the inner and outer Oort cloud and the far distant comets formed from the very beginning of the solar system. These comets have been in the cold about 10 degrees above absolute zero) for billions of years and the extreme low temperatures and extreme distance from the sun have allowed them no interaction with other solar bodies. This allows their composition to be basically unchanged since the beginning of the solar system.
We see mans quest to find the composition of comets using high altitude U2 planes to get cosmic dust for study.Many spacecraft shot up for photos of comets, solar wind detection, and trying to get any comet particles. Fascinating stuff.
Lots of info on the favorite comet Halley plus lots of information on the scientist Halley. Lots of other comets mentioned plus their orbits shown.
Talk of possible future colonization of the comets in the Oort cloud and growing gigantic trees on the comet... miles high and wide! Kind of Sci Fi to me but interesting.
Comet is a fascinating book both for the novice who has never seen a comet, the 40 year amateur astronomer like me, and the professional astronomer/scientist. All will appreciate this book. There is no difficult math. All will enjoy the many pictures and parents can show and tell their child from this book. Would make a great book for middle school, high school or a college astronomy 101 course.
Also got out of this book there is so much that we don't know about comets, especially about the extreme orbit comets but we are learning more everyday. Do yourself and family a favor. Next time a naked eye comet event happens enjoy it. You may not even need binoculars or a telescope. Halley comes around every 75 years, some comets less time, some more time and some are never seen again explosion, decomposition or flung out of their orbits by gravitation slingshot effect by Jupiter or more reasons). Just a fascinating sight to see out your backyard sky. If you have the chance enjoy.
I sure miss Carl Sagan. Even though he never knew of me, I knew of him and consider him a friend.