1 / 34

Planetary motion

Planetary motion. Watching the sky night after night, month after month, some “stars” appear to move Planetary motion is much slower than diurnal motion Five “wandering stars” known to ancient people were Mercury, Venus, Mars, Jupiter, and Saturn. Greek Astronomy (Aristotle & Ptolemy).

schuyler
Télécharger la présentation

Planetary motion

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Planetary motion • Watching the sky night after night, month after month, some “stars” appear to move • Planetary motion is much slower than diurnal motion • Five “wandering stars” known to ancient people were Mercury, Venus, Mars, Jupiter, and Saturn.

  2. Greek Astronomy(Aristotle & Ptolemy) • Believed that the earth was at the center of the universe • All heavenly objects moved on perfect circles • Models became very complicated to explain retrograde motion • Adopted by Catholic theologians in the Middle Ages

  3. animation

  4. Nicolaus Copernicus (1473-1543) • Born Nicolaus Kopernik in Poland • Priest, mathematician, and physician • Proposed that the earth is not at the center of the universe • Explained retrograde motion of planets without epicyles

  5. Tycho Brahe(1546-1601) • Born in Denmark to noble family • Made the most accurate observations up to that time without a telescope • Measured • positions of stars & planets • length of year (to within 1 second) • distance to supernova

  6. Parallax

  7. Galileo Galilei(1564-1642) • Italian inventor and physicist • First to use a telescope for astronomy • Discovered: • craters & mountains on the moon • moons of Jupiter • phases of Venus • convicted by Inquisition at age 70 and forced to recant his theories

  8. Phases of Venus

  9. Johannes Kepler(1571-1630) • Hired as assistant to Tycho Brahe a year before Tycho’s death • Used Tycho’s data to work out first truly accurate model of solar system • Obsessed by idea of “harmony of the spheres”

  10. Kepler’s Laws • The orbit of a planet is an ellipse with the sun at one focus • A line joining a planet and the sun sweeps out equal areas in equal intervals of time • The square of a planet’s period is directly proportional to the cube of the orbit’s semimajor axis P2 = a3

  11. animation

  12. Sir Isaac Newton(1643-1727) • Lucasian Professor of Mathematics at Cambridge University, England • Invented calculus (at the same time as Leibnitz in Germany) • Studied the nature of light • Combined physics and astronomy for the first time

  13. Newton’s Laws of Motion • Every object tends to remain in constant motion unless acted upon by an outside force • Force equals mass times acceleration F=ma • For every action there is an equal and opposite reaction

  14. Newton’s Law of Universal Gravitation All objects attract each other with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between them.

  15. Newton’s Laws explain planetary motion • Physics can predict Kepler’s Laws • Not all orbits are ellipses! • Parabolas and and hyperbolas are also possible (one time orbits)

More Related