# Tag Info

Accepted

### On Mars, why are the seasons "strongly amplified" in the southern hemisphere and masked in the northern hemisphere?

Your solution is correct. Mars has a perihelion that is, coincidentally, quite close to the southern Hemisphere summer solstice. Perihelion is actually about one (Earth) month before the solstice. ...
• 118k
Accepted

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

Both ellipticity $f$ (also called flattening) and eccentricity $e$ are measures of how elongated an ellipse is, based on the semi-major axis $a$ and the semi-minor axis $b$ (figure from wikipedia). ...
• 16.3k

### On Mars, why are the seasons "strongly amplified" in the southern hemisphere and masked in the northern hemisphere?

Apart from the eccentricity you pointed out that has a role in a difference in the weather, one more factors that plays a role is the difference in the terrain and topology between the hemisphere. ...
• 4,436

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

Ellipses have a "long radius" called the "semi-major-axis" which is the length from the centre to the ellipse measured along the long axis. And a "semi-minor-axis" which ...
• 118k
Accepted

### Why has the orbit of Venus such a low eccentricity?

It has a low eccentricity, but there may not be a particular reason. Image by Kheider on wikipeda using Gravity Simulator by Trevor Dunn In a simulation of the solar system, both Earth and Venus had ...
• 118k

### Does gravitational radiation change the eccentricity of binary orbits?

Yes. There's an intuitive way to see this without reproducing all of the messy GR equations (which appear in a Physics StackExchange answer pointed to by @PM2Ring in a comment). The amount of ...
• 687

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

There are two types of angular momentum of each planet: orbital angular momentum of the planet around the Sun, and rotational angular momentum of the planet around its rotational axis. Orbital angular ...
• 16.3k
Accepted

### Lagrange points for bodies in elliptical orbits?

One of the answers to the researchgate question What are the equation of motion for elliptical restricted three body problem? says: https://www.sciencedirect.com/search?qs=equation%20of%20motion%...
• 31.2k
Accepted

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

You are doing many things wrong. You are computing the eccentricity of one body with respect to the center of mass. You need to compute the eccentricity of one body with respect to the other. You ...
• 33.7k
Accepted

### Eccentricity and Inclination of a Star

Sirius is a binary system, composed of a main sequence star (Sirius A) and a white dwarf (Sirius B). The two orbit each other with a period of about 50 years, and the eccentricity given on Wikipedia ...
• 36.3k
Accepted

### How close to circular is the Earth's equator

My answer won't be complete, from lack of time and resources, but I still wanted to share some interesting aspects here that could be helpful. The difficulty in aswering this question revolves around ...
• 1,006

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

The timeanddate.com article says: If the Earth’s orbital path was elliptical, but its axis not tilted, the Solar Analemma curve would be oval shaped. At the Equator, this line would be a straight ...
• 18.6k
Accepted

### Best way to procedurally generate an orbit given mass and eccentricity

ANSWER I would put the massive object at the origin. Then, I would calculate the velocity at periapsis, when $r=a(1-e)$ as $$v = \sqrt{GM\frac{1}{a}\left(\frac{1+e}{1-e}\right)}$$ (stolen from Uhoh's ...
• 16.3k

### Neptune's eccentricity stability

tl;dr: It will be around the year 14,800 that Earth's eccentricity drops below that of Neptune's. It's unusual to post two answers, but this one is sufficiently different that in this case I think it'...
• 31.2k

### Neptune's eccentricity stability

Earth's Eccentricity varies between about 0.000055 and 0.0679. This is the first Milankovich cycle. When Earth' eccentricity is at its lowest, it is lower than that of Neptune. The Earth's orbit ...
• 118k
1 vote
Accepted

### Eccentricity of TLE orbit from velocity and radius in TEME

For orbits with non-small eccentricities (say e>0.1) that never get very close to Earth for atmospheric or higher order multipole terms, your biggest error will come from Earth's J2 term, the "...
• 31.2k
1 vote

### Which one of the gas and ice giants has the least varying orbital characteristics?

JPL Solar System Dynamics has produced the variations. The original page is not available that I can find but the Wayback Machine has it archived, and I have included a copy below. The first line ...
• 5,622
1 vote

### Calculation of Eccentricity of orbit from velocity and radius

One uses the so called eccentricity vector, also called (up to a factor) Laplace-Runge-Lenz vector. Given the position $$\vec{r} = \begin{bmatrix}x\\ y\\ z\end{bmatrix}$$ of the object at given time ...
• 121

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