On the Revolutions of the Heavenly Spheres

OF THOSE THINGS

WHICH ARE CONTAINED IN THE INDIVIDUAL CHAPTERS

of the six books of Nicolaus Copernicus, On the Revolutions

of the Heavenly Spheres.

BOOK ONE.

1. That the world is spherical.
2. That the earth also is spherical.
3. How the earth with water forms one globe.
4. That the motion of the heavenly bodies is uniform and circular, perpetual, or composed of circular motions. Copernicus adheres to the classical ideal that celestial motions must be perfectly circular, even as he moves the Earth.
5. Whether a circular motion belongs to the earth, and concerning its location.
6. Concerning the immensity of the heavens compared to the size of the earth.
7. Why the ancients thought that the earth remained at rest in the middle of the world, as if it were the center.
8. Solution to the aforementioned arguments, and their insufficiency.
9. Whether several motions can be attributed to the earth, and concerning the center of the world.
10. Concerning the order of the heavenly spheres. This chapter contains the famous diagram of the heliocentric system.
11. Demonstration of the triple motion of the earth.
12. Concerning the magnitude of straight lines in a circle. original: rectarum in circulo linearum; this refers to the calculation of chords, a foundational element of trigonometry used for astronomical measurements.
13. Concerning the sides and angles of plane rectilinear triangles.
14. Concerning spherical triangles.

BOOK TWO.

1. Concerning circles and their names.
2. Concerning the obliquity of the zodiac circle original: signiferi, literally "the sign-bearer." This refers to the ecliptic, the apparent path of the sun through the constellations., and the distance of the tropics, and how they are determined.
3. Concerning the circumferences and angles of the intersecting circles—the equinoctial, the zodiac, and the meridian—from which come declination and right ascension These are the celestial equivalents of latitude and longitude used to locate stars., and the calculation of these.
4. How the declination and right ascension are revealed for any star outside the circle that runs through the middle of the signs, provided its latitude and longitude are established, and with what degree of the zodiac it reaches the mid-heaven.
5. Concerning the sections of the horizon original: finitoris, an older term for the horizon, the circle that "finishes" or limits the viewer's sight..
6. What the differences of the midday shadows are.
7. How the longest day, the latitude of sunrise, and the inclination of the sphere are demonstrated in turn, and concerning the other differences of the days.
8. Concerning the hours and parts of the day and night.
9. Concerning the oblique ascension of the parts of the zodiac, and how for any degree rising, the one that reaches mid-heaven is also given.
10. Concerning the angle of intersection of the zodiac with the horizon.
11. Concerning the use of these tables.
12. Concerning the angles and circumferences of those circles which are made through the poles of the horizon to the same circle of signs.