Why Do the Planets Orbit the Sun in an Elliptical Fashion?
- Written By: Laura Martinelli
- Edited By: Lucy Oppenheimer
- Last Modified Date: 03 April 2013
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Copyright Protected:
2003-2013 Conjecture Corporation
Planets orbit in the shape of an ellipse because of the gravitational interactions between planets and the Sun, along with other celestial bodies. Johannes Kepler in the 1600s was the first to start discussing the shape of planetary orbits, formulating a series of laws to explain their shape and characteristics. Isaac Newton and Albert Einstein contributed additional research and theories to the body of knowledge about how planets move through space.
Kepler determined, according to his first law of planetary motion, that the orbits of the planets are elliptical in shape, with the Sun at one focus of the ellipse and the shape of the ellipse being measured in terms of eccentricity; the more eccentric an orbit, the more elongated it is. Many planets, like Earth, have orbits that are very close to being circular, while others, like Mercury, have more eccentric ones. Kepler did not determine why they orbit in an ellipse, but his groundwork was used by other physicists who came up with concrete explanations.
Newton contributed the factor of gravity, showing how planets pull on each other and the Sun, as the Sun also exerts a gravitational pull on them. This has the effect of squashing orbits that one might expect to be circular in a closed system, as the gravitational pulls act on each other like many hands pulling taffy. Einstein's theory of relativity also plays a role in explaining why planets orbit the Sun in an elliptical fashion, as part of the shape of the orbits is a result of the curvature of space caused by planets acting on the space-time around them.
Using mathematical rules established by a number of physicists and astronomers, people can accurately calculate the orbit of individual planets as well as entities like comets and they can also track the degree of change over time. This information is useful for a number of applications, from programming telescopes for observation to determining the degree of threat posed by an approaching comet or asteroid.
It is important for people to remember that many descriptions of planetary orbits are simplistic, placing the Sun as a fixed body in space that planets move around. In fact, the Sun is in motion along with the planets, and as they move through space, the precise shape of the orbits also changes over time. This should be kept in mind when looking at discussions of the way the planets orbit around the Sun, as the entire orbital system is moving.
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Discuss this Article
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anon301218
Post 16 |
I don't feel that this post answered the question it proposed. |
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anon299439
Post 15 |
If space is curved. How in the hell its not circular? I do not think other planets affect one another. Einstein was a speculator. He was wrong about space time. He is wrong about many things. E=mc2 is an idea he stole from another scientist when he worked in the patent office. |
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anon279438
Post 14 |
I thank whoever contributed the first paragraphs. So many resources dance around the question without producing a simple answer to a complex question. Kepler's mathematical formulas probably provide a clue but I don't want to get into this. The explanation that other gravitational sources contribute to the orbits being elliptical rather than a circular are satisfying for me. --CBBates |
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Gottlieb980
Post 13 |
I suggest readers consult the many articles NASA scientists have published on the cause and nature of elliptical orbits. These are articles by genuine scientists, not amateur speculators like Miles Mathis. Mathis is not a scientist and has never done the work necessary to become one. Aside from writing crackpot opinions on his website he has no credentials whatsoever and lives isolated in a hovel in Taos, NM. Mathis believes 9/11 and the moon landings were hoaxes and that the value of pi is not 3.14 but 4.0. Please do not be deceived by an internet kook. Learn your science from a scientist. |
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anon276231
Post 11 |
According to Miles Mathis in "explaining the Ellipse," Newton posited an innate motion which is the same throughout, but showed there. Gravitational acceleration is stronger at perihelion than aphelion. This requires that the curved arc at perihelion must be smaller/ tighter than at aphelion. Both express vectors. This means that, in order to have an ellipse, another force is required. I suggest readers research Miles Mathis explaining the ellipse, and learn for themselves that there is a serious problem between Newton's law and the shape of elliptical orbits. They can then post their mathematical criticisms for Mathis to address. To date, no one has shown he is in error mathematically. |
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anon215942
Post 10 |
@anon63169: While there is no physical object there, the common center of gravity of the object and the Sun lay at that point. For an example, the common center of gravity for Earth - Moon is actually inside the Earth, but we still orbit it. |
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leesmithjr
Post 8 |
I suspect that elliptical orbits originated from the spiral nature of the early solar system. As the planets formed from the condensate, they had a slight angular momentum like incoming projectiles that were captured in the warped space-time (a.k.a. "gravity") of the sun and this created the non-circular configurations. |
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anon109831
Post 6 |
I see now that the gravitational pull of the sun has something to do with it. |
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anon108809
Post 5 |
You are explaining why planets orbit the sun in an elliptical path and the answer is planets orbit the sun in an elliptical path by kepler's law.
Moderator's reply: We have revised the text of this article; the explanation should be clearer now. |
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anon63169
Post 2 |
why an ellipse if there is "nothing at the other focus point"? |
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anon24011
Post 1 |
I love this article. its so amazing that i've been very inspired and i want this astronomy to be my goal and inspiration for the rest of my living. Keep up the good searching and keep on inspiring people like me! |
