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Questions tagged [eccentricity]

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3
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1answer
49 views

Path of sun in the sky on a planet with no axial tilt

Some sources online (e.g. this, see section "Effect of Earth’s Eccentricity") claim that if the earth's axis was not tilted, then the analemma would have the shape of an ellipse/oval. I ...
3
votes
1answer
108 views

Best way to procedurally generate an orbit given mass and eccentricity

As stated here, I've badly expressed my problem and have made what we call a XY problem (the question was well answered nonetheless) so I restate the question. Sorry for the inconvenience I have a 2D ...
3
votes
1answer
210 views

Is the 'spin' of Earth and the 'spin' of Mars a significant contribution to their angular momentum?

Is the 'spin' of Earth and the 'spin' of Mars taken into account as a contribution to the conservation of angular momentum? (and a contribution to the increasing/decreasing eccentricity?) Or - is the ...
10
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2answers
2k views

What is the difference between the two terms named "Eccentricity" and "Ellipticity"?

I don't get the difference between the two terms named "Eccentricity" and "Ellipticity", especially, in astronomy. I understand eccentricity as a measure of the curvature of a ...
2
votes
0answers
21 views

Relation between inner and outer eccentricities in a hierarchical triple star system

According to Table 3 of Sterzik & Tokovinin (2002), the inner eccentricity of a triple star system (i.e. the eccentricity of the inner binary) is, most of the times (70%), larger than the outer ...
6
votes
1answer
366 views

Cannot identify mistake in calculating orbital eccentricity vector; magnitude equals one instead of zero (with python code)

I have a gravitational nbody simulation, for which I would like to determine various orbital parameters. For each body, I have 3-D vectors (x,y,z -space) for position, velocity, and acceleration. I am ...
3
votes
0answers
52 views

Does gravitational radiation change the eccentricity of binary orbits?

Do the eccentricity of a binary orbit change with change in the semimajor axis due to loss of orbital angular momentum by gravitational radiation?
3
votes
1answer
82 views

What kind of effects can maintain Uranus' rings' eccentricities?

The recent paper Thermal Emission from the Uranian Ring System has been in the news recently. The introduction mentions: The ε ring, the brightest and most massive of the narrow rings, was shown to ...
2
votes
1answer
283 views

How close to circular is the Earth's equator

Earth's orbit is about 99% circular. How circular is Earth around the equator? I know it bulges around the equator and is a spheroid. I also know it is not smooth and has oceans and mountains and all ...
1
vote
2answers
2k views

Calculation of Eccentricity of orbit from velocity and radius

For a school project I am making a gravitational computer model. As I want to Milankovitch cycles, I need to calculate the eccentricity of an orbit after the model has completed its simulation. I ...
9
votes
1answer
346 views

Why has the orbit of Venus such a low eccentricity?

The eccentricity of Venus is almost 14 times smaller than that of Mars, and 2.5 times smaller than that of Earth, and 30 times smaller than that of Mercury. Is it just a pure fluke? Or is there some “...
1
vote
1answer
132 views

Eccentricity and Inclination of a Star

I understand Planetary Eccentricity and Inclination. However when it applies to a star, does the centre or ecliptic plane refer to the Sun or the Galactic Centre? The star Sirius for example, 136....