All Questions
Tagged with history orbital-motion
31 questions
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Kepler's measurements in solar system
I am interested in knowing that does Kepler measured distances in solar system or only relative distances to a astronomical unit which he doesn't know how long is it in our meters.
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Gravitational attraction between two bodies
While the gravitational force between two bodies is directly proportional to their masses, and inversely proportional to the distance between them is understandable / seems logical, how did Newton ...
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202
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How does sweeping out equal areas in equal times show that the orbit is not a circle?
In many popular accounts, Kepler is said to have discovered that the planets move in an ellipse and not a circle after discovering that the planets sweep out equal areas in equal times. For example, a ...
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Did Newton derive Titius-Bode Law of the planets in his Principia? [closed]
In college I was taught that no one knows why the planetary orbits conform to the Titius-Bode Law.
Recently I read that Newton HAD figured that out in his Principia.
Right Now I can’t even find a ...
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How do we know orbits go in an elliptic shape?
I never really understood how we found out the orbits our planets follow are elliptical and not in a circle.
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How could Tycho Brahe determine positions without accurate clocks?
Tycho Brahe determined the positions of stars and planets to an accuracy of 2 minutes of angle. Pendulum clocks hadn't been invented yet so he couldn't have known the time to better than 15 minutes. ...
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Kepler's laws of motion [duplicate]
I have studied Kepler's Law of Motion but I always think how did Kepler arrive to those laws and what were the basic thinking behind it?
I just want to know the basic physics behind his ideas.
I know ...
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Were Kepler's Laws of Planetary Motion the first formal definition of an ellipse?
It seems to me that Kepler's Laws necessitate some definition of an ellipse in terms of a coordinate system. I am wondering whether Kepler's Laws mathematically defined what an ellipse is, or if he ...
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Why was Einstein wrong about black holes?
In 1939, Albert Einstein published a paper entitled "On a Stationary System with Spherical Symmetry Consisting of Many Gravitating Masses." In it, he considers the problem of whether it is ...
- 4,110
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Kepler papers (2-body problem) [closed]
Where can I find papers by Kepler? I am looking for his solution to the two-body problem.
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'Harmony of the Spheres' or 'Harmony of the World' - is it debunked? [closed]
I sincerely apologise for this vague question but I'm writing an essay for my music class on musical harmony and it's historical origins. I came across the Pythagorean notion of Harmony of the Spheres ...
user136975
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How to prove Kepler's 3rd law? [duplicate]
How to prove Kepler's 3rd law? How did Kepler proved it? Is it possible to prove the third law without applying Newton's universal law of gravitation?
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Where did Paul Gerber go wrong in arriving at the same equation as Einstein in explaining the Mercury anomaly?
We know that Einstein admitted that Paul Gerber's 1898 formula explaining the anomaly of Mercury's perihelion was the same as his own. Reportedly Gerber had made a mistake somewhere, so - even though ...
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Kepler's genius, How?
I have a very simple question. How Kepler knew that orbits are elliptical, say I was living in his time. How would Kepler explain that the orbits are elliptical (since none of his 3 laws explain why ...
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Did Newton know or assume that planetary (extraterrestrial) space was frictionless vacuum-space?
For a correct calculus of the perpetual orbital motion of planets as determined by Newton’s laws of gravitation, frictionless motion through interplanetary vacuum space would have been a prerequisite. ...
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How can it be known what the Earths periods of eccentricity, perihelion and obliquity are when the observational data only cover at most 3,000 years?
How can it really be known what the earths periods of eccentricity, perihelion and obliquity are when the observational data only cover at most 3,000 years? What I mean is that these parameters ...
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The cosmological constant and the precession of Mercury
In the beginning of the last century, the Nobel physics subcommittee – made up of experimentalists detached from the dramatic developments of theoretical physics on the continent – was surprized both ...
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Was Leverrier-Adams prediction of Neptune a lucky coincidence?
According to historians both Adams and Leverrier used Bode's law to guess the distance to Neptune, which led to a vast overestimation of its orbital period (Adams - 227 years, Le Verrier - 218 years, ...
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What made Kepler think that orbits are not circular which came to be elliptical?
Kepler formulated his laws in a sort of time where human began to believe in heliocentric universe and telescope was not yet invented/ discovered. So what made Kepler think that orbits aren't circular?...
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How did Kepler infer three-dimensional positions from Tycho Brahe's data?
This has bugged me for some time.
Tycho Brahe's data on planetary observations, presumably, consisted of the direction in which a planet was observed at a given date and time, but not the distance to ...
- 135k
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How did Kepler formulate his second law from data?
It's amazing that Kepler derived his three laws emperically and then Newton rederived them from his own laws of motion. Its conceivable how Kepler derived the first and third laws, but the second law? ...
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How did Kepler arrive at his laws?
How did Kepler arrive at his laws? If one already knows the distances to the planets (and the eccentricity of the orbits, etc.), it is understandable that one might proceed to establish Kepler's ...
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How did pre-Copernican astronomers accurately predict planetary position?
Copernican elements (circular orbital elements) are not very accurate. But Copernicus simplified our understanding a great deal by placing the Sun at the center of the system. Im astonished by the ...
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What are "cycles of anomaly" and "cycles of longitude"?
In several early (pre-1600) astronomical texts I read about "cycles of anomaly" and "cycles of longitude", but it us unclear to me what these terms mean. They were clearly familiar to authors at the ...
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What is the angular distance between Ptolemaic perigees of Mercury?
In his excellent treatment of the history of the science of astronomical distances and sizes, Albert van Helden says (p.29) that
The complicated [Ptolemaic] model of Mercury has the curious ...
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How did Copernicus establish the relative distance to the superior planets?
I understand that the relative distances to the planets had been calculated using various methods since ancient times, and, in particular, that the assumptions of the Copernican model of the Solar ...
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Did Aristarchus take the radius of the Earth into account in calculating the distance to the Moon?
My text says that Aristarchus (310 BC – ~230 BC) measured the "angle subtended by the Earth-Moon distance at the Sun" ($\theta$ in the figure below) to establish the relative Earth-Moon and Earth-Sun ...
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When and how were relative distances to the planets first measured?
I understand that the absolute distance to a planet can be measured using earth-baseline (e.g., diurnal) parallax, and that the first reasonably accurate such measurement was made for Mars by Cassini (...
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Was Jupiter's mass "guessed at" by Kepler or Galileo?
Following Kepler's publication of his 3rd law of planetary motion1,
$$p^2 / r^3 = 1$$
in 1619, it would have been possible to use telescopic observations to arrive at an estimate of the orbital ...
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Why did the ancients fail to discover that the Earth orbits the Sun? [closed]
The ancients observed that the Sun and the 'fixed' stars rotated about the Earth. They were also aware that the Earth was spherical. They performed many astronomical measurements on the planets - ...
Alan-UK
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Historically, how do we know that Earth moves around Sun? And it does so in an elliptical orbit?
I know the basics of solar system like how Earth moves around Sun, and that we have so many planets, elliptical orbit of earth, and how far is sun from earth etc etc. I want to take a step back and ...
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