Nicolaus copernicus 1473 1543 sought to develop a

This preview shows page 25 - 28 out of 35 pages.

Nicolaus Copernicus (1473-1543) Sought to develop a simple model of planetary motion without the weaknesses of the Ptolemaic model: - The equant point requires non-constant motion. - The planets have an ambiguous order. - No explanation for the connection between the motion of the planets and the Sun The Copernican Model - In 1514, Copernicus published his heliocentric (Sun-centered) model in “Little commentary”. - He attributes the daily motion of the sky to earth’s daily spin. - The annual motion of the Sun is attributed to Earth’s annual orbit.
Image of page 25

Subscribe to view the full document.

Animation: Earth's Precession - Copernicus showed retrograde motion occurs when Earth overlaps (or is overlapped by) a planet. Animation: The Cause of Retrograde Motion In a heliocentric model, the distance between Earth and a planet can vary. Therefore: - A planet’s angular speed can vary - A planet’s brightness can vary In a heliocentric model: - Venus and Mercury become inner planets (explains their different paths) - The longer a planet’s orbital period (P), the larger its orbital radius (R). - Copernicus’ heliocentric model was ridiculed by some Christian scholars, while others encouraged him to publish his full theory. - In 1543, Copernicus published his complete heliocentric model (de Revolutionibus). For the next 1/2 C, the Copernican and Ptolemaic models were the two leading models of planetary motion. NATS 1745 (Oct 26. 2010 ) notes:
Image of page 26
Chinese astronomers recorded the temporary appearance of “new stars”, now called novac (Latin: “new”) or supernovac. (diagram: CH2-18) These events are really the temporary brightening of a dying star Novac and supernovac occur rarely and randomly in our Galaxy ( on average, 1/century) Records of supernovac coordinates have been matched with present-day nebulac, proving: nebulac are supernovac remnants The recorded date of a supernova gives the age of its stellar corpse and the nebula’s expansion rate (-1000s km/sec) Astronomy in Ancient Egypt (3200-331BC) In ancient Egypt, survival depended on the annual flooding of the Nile River. Thus the sky was mainly studied for accurate time keeping. The annual cycle of the stars (diagram: CH2-20) due to earth’s annual orbit around the sun, our visible window of stars changes each night ( i.e. the stars we see depend on the time of year) The Egyptian Religious Calendar When a stars returns to the exact same position in the sky, earth has completed 1orbit (i.e. exactly 365.25 days have elapsed) Within the latitudes of Egypt, the heliacal rise of Sirius (the brightest start in the sky) coincides with the Nile’s annual flood. The heliacal rise was therefore used to mark each year. The origin of the leap year The government of Egypt established a civic calendar containing 12 30 day months (360 days) with 5 “leaps” days to stay synchronized with the 365-day seasonal cycle.
Image of page 27

Subscribe to view the full document.

Image of page 28
  • Fall '11
  • RobinMetcalfe

{[ snackBarMessage ]}

Get FREE access by uploading your study materials

Upload your study materials now and get free access to over 25 million documents.

Upload now for FREE access Or pay now for instant access
Christopher Reinemann
"Before using Course Hero my grade was at 78%. By the end of the semester my grade was at 90%. I could not have done it without all the class material I found."
— Christopher R., University of Rhode Island '15, Course Hero Intern

Ask a question for free

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern