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Recommended: The Elements of Astronomy
Recommended: The Elements of Astronomy

Recommended: The Elements of Astronomy

The Elements of Astronomy by Simon Newcomb appears to be a good introductory book to astronomy. You can see chapter 2 of the book at the Website of the physics department of CSBSJU or you can download a PDF of the entire book on the Internet Archive for free. The book was printed in 1900 and is now, from what I have read, out of copyright. Some parts of the book might be out of date, but in many respects the book is not: our solar system and the causes of its motion remain the same. Elements has some concise, effective explanations and diagrams. Here is a diagram used in the explanation of the seasons:

Since the earth’s axis stays pointing the same direction (in the short run; I am not considering precession) as the earth travels around the sun, a different hemisphere is towards the sun on the left (at point B) than on the right of the diagram. At point B, the Northern hemisphere is toward the sun, so the Northern hemisphere has summer. At point D, the Southern hemisphere has summer. This diagram shows day vs. night:

And more. EQ is the equator. AC and MN define the Arctic and Antarctic Circles. FG and KL define the Tropics because they are the furthest North and South the sun appears to rise above and below the equator during the year (at Summer and Winter Solstice, at an angle of 23.5 degrees above and below the equator). An illustration of the apparent path of the sun to an observer standing in the middle of the circle:

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