What is Kepler: Definition and 120 Discussions

Johannes Kepler (; German: [joˈhanəs ˈkɛplɐ, -nɛs -] (listen); 27 December 1571 – 15 November 1630) was a German astronomer, mathematician, and astrologer. He is a key figure in the 17th-century scientific revolution, best known for his laws of planetary motion, and his books Astronomia nova, Harmonices Mundi, and Epitome Astronomiae Copernicanae. These works also provided one of the foundations for Newton's theory of universal gravitation.
Kepler was a mathematics teacher at a seminary school in Graz, where he became an associate of Prince Hans Ulrich von Eggenberg. Later he became an assistant to the astronomer Tycho Brahe in Prague, and eventually the imperial mathematician to Emperor Rudolf II and his two successors Matthias and Ferdinand II. He also taught mathematics in Linz, and was an adviser to General Wallenstein.
Additionally, he did fundamental work in the field of optics, invented an improved version of the refracting (or Keplerian) telescope, and was mentioned in the telescopic discoveries of his contemporary Galileo Galilei. He was a corresponding member of the Accademia dei Lincei in Rome.Kepler lived in an era when there was no clear distinction between astronomy and astrology, but there was a strong division between astronomy (a branch of mathematics within the liberal arts) and physics (a branch of natural philosophy). Kepler also incorporated religious arguments and reasoning into his work, motivated by the religious conviction and belief that God had created the world according to an intelligible plan that is accessible through the natural light of reason. Kepler described his new astronomy as "celestial physics", as "an excursion into Aristotle's Metaphysics", and as "a supplement to Aristotle's On the Heavens", transforming the ancient tradition of physical cosmology by treating astronomy as part of a universal mathematical physics.

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  1. P

    Stargazing Kepler Telescope is so productive?

    Arccording to Nasa, the Kepler telescope will be working for 3.5 years in orbit and during that time it will observe about 100000 stars looking for exoplanets. Howcome it can finish for that workload?
  2. Y

    Kepler & Einstein: Agree or Disagree?

    Imagine we have an ideal Schwarzschild black hole. A small satellite of insignificant mass (so that the Shwarzchild geometry remains ideal) is orbiting at coordinate radius R just outside the photon orbit in a perfect circular orbit. For the purpose of this experiment ignore the orbital decay...
  3. P

    Galaxy rotation and Kepler law

    According to Kepler third law, the ratio of the squares of the periods of any two planets is equal to the ratio of the cubes of their average distances from the sun. If I can apply this to the rotaion of galaxy, meaning stars in inner part will orbit much faster than the outer ones. But it...
  4. A

    What did Kepler do for the field of mathematics?

    What were some of Kepler's mathematical concepts? After a little research, I have discovered Kepler's conjecture (the sphere packing), how ellipses (foci, eccentricity, etc) correspond to Kepler's first law, and a few formulas here and there. What else did he do?
  5. S

    Solving Kepler's Equation for Comet Orbit Time Around Sun

    Homework Statement A comet is 10 times farther from the sun than the Earth. Find the time it take to make its orbit around the sun. Homework Equations T^2/R^3 = K K= 3.36X10^18 The Attempt at a Solution I tried to create a ratio, but I honestly have no idea where to start...
  6. B

    What is the volume of a cylindrical wine barrel with a bung hole?

    Homework Statement A wine barrel has a hole in the middle of its side called a bung hole. To determine the volume of the wine in the barrel, a bung rod is inserted in the hole until it hits the lower seam. You should make the following assumptions: -The barrel is cylindrical -The bung...
  7. 3

    Kepler's Third Law and Newton's Law of Universal Gravitation for Planet P

    Homework Statement a. Planet "P" has a mass that is 2.89 times that of the Earth, an equatorial radius that is 1.89 times that of the Earth and is located 7.8 times further from the Sun than the Earth is. What is the amount of force applied to the planet by the Sun? b.what is the orbital...
  8. quasar987

    Is My Calculation for the Conserved Quantity in the Kepler Problem Correct?

    There must be something I'm totally missing here. The situation is the following. I am asked to show that given the lagrangian for the Kepler problem, L=\frac{1}{2}\mathbf{\dot{q}}^2+q^{-1} the k-th component of the Runge-Lenz vector...
  9. W

    Understanding Kepler's Laws and Parallax in Astronomy

    I have been reading into Kepler's laws lately because I am absolutely intrigued by space and the cosmos, but the second one about equal time and equal areas doesn't quite make sense on wikipedia or the physics textbook (Giancoli 3rd Edition i believe)... and can someone help me understand...
  10. M

    Galaxy defy Kepler? True or bull?

    I was watching a show about black holes at the centers of galaxies. And (perhaps I misheard), but there was a one line comment made to the effect that stars in a spiral galaxy don't always move around the center of a spiral galaxy in accordance with Kepler's laws (which, by that, I assume...
  11. marcus

    What is the significance of Kepler Day and why should we celebrate it?

    Kepler is the patron saint of quantum gravity and 15 May was the day Kepler had a really new idea which he called "sesquipotentia" or "one and a half power" law. He recorded in his diary that the idea had occurred to him on 8 March but he dismissed it, thinking it was wrong, and then on 15...
  12. fargoth

    Understanding the Vis-Viva Equation for Elliptical Orbits

    im a private teacher now for first year students... and today my student asked me a question i didnt know the answer to... so i said i'll look it up, but I am going out with friends :-p so if you could help and save me the time id really appreciate it. the problem is finding the maximum...
  13. A

    Kepler orbital trajectories and 'effective potential'

    Ok so the total energy of a body following a given trajectory around a much larger body (eg. Earth and sun), is described by : E(total) = (1/2)mv^2 + U (where U = grav. potential energy) E(total) = (1/2)mv^2 - (GMm)/r (1/2)mv^2 can then be expanded to give : E(total)...
  14. G

    Eccentricity in kepler problem

    For a planet moving in an elliptical orbit, fraction of maximum and minumum angular is given to be n \frac{\dot{\theta}_{max}}{\dot{\theta}_{min}} = n Show that \varepsilon = \frac{\sqrt{n}-1}{\sqrt{n}+1}. I keep finding \varepsilon = -\frac{n^2-1}{n^2+1} Can someone show a path to correct...
  15. C

    Estimating Number of Stars in Milky Way Galaxy: Kepler Problem Solution

    Our Sun, with mass 2.0 1030 kg, revolves about the center of the Milky Way galaxy, which is 2.2 1020 m away, once every 2.5 108 years. Assuming that each of the stars in the galaxy has a mass equal to that of our Sun, that the stars are distributed uniformly in a sphere about the galactic...
  16. C

    Calculating Altitude of Synchronous Orbit on Rotating Pluto

    A satellite hovers over a certain spot on the equator of (rotating) Pluto. What is the altitude of its orbit (called a "synchronous orbit")?
  17. wolram

    Asteroseismic Analysis of Kepler Data

    http://arxiv.org/pdf/astro-ph/0406437
  18. arivero

    Relativistic Kepler Problem: Minimum Momentum & Quantum Gravity

    Reading around Sommerfeld, I noticed a suppossedly very well known result: that orbits in the relativistic kepler problem have a minimum momentum. It is a special relativity result, and I do not know if it is related with the problem of the existence of stable orbits in GR; the later are orbits...
  19. arivero

    Calculating the Quantum Kepler Length of a Particle

    One knows that in classical gravity a orbiting point sweeps equal areas at equal times. It can be seen that for macroscopic distances the area swept in a plank time is a lot greater than the minimum quantum of area, which is about (plank length)^2. Now, I ask, given a particle of mass m, for...
  20. marcus

    Was Kepler a Scientist? On May 15 of 1618

    On May 15 of 1618 Kepler realized that the 3/2 power of an orbit's size tells you its period he kept a diary and recorded how he came to his ideas and when the insight occurred and what if felt like he says he had a premonition of it in March of that year and couldn't believe it and...
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