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The Sun and most of the other stars are in the bulging disk of the Milky Way galaxy, but about 1% of the galaxy's stellar mass is in the galactic halo. The halo also includes 50 globular clusters and about 20 satellite galaxies according to Helmi 2008: The stellar halo of the Galaxy. Here is a nice graphic: Note that the Sagittarius Stream of stars is ...


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Most stars in the galaxy are in the disc, but there is also a population in the galactic halo, these are in orbits at essentially random inclinations to the disc. There will be some that orbit perpendicular to the galactic plane. Most of these stars are red dwarfs and very old (more than 12 billion years old) and formed early on in the evolution of the ...


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Planetary orbits are normally described as heliocentric, but it is possible to describe them from a barycentric point of view. JPL Horizons (https://ssd.jpl.nasa.gov/horizons.cgi) provides for both possibilities.


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The Wikipedia article version in question took the aphelion and period from barycentric elements generated by JPL HORIZONS, and everything else from heliocentric elements listed in the JPL Small Body Database. Such mixing is inappropriate; as you noticed, it violates such rules as $$ \frac{q}{1 - e} = \frac{Q}{1 + e} = a $$ Then what set of elements should ...


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That's Wikipedia for you. The linked page demonstrates that Wikipedia is not a reliable source. Here are some of the problems: The values for aphelion, perihelion, semi-major axis, and eccentricity are inconsistent with one other. The values for perihelion, semi-major axis, and eccentricity are unsourced. The values for perihelion, semi-major axis, and ...


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Tycho was concerned that the Earth must be too "heavy" and "sluggish" to move. So his system solves this problem. It turns out not to be a problem at all. The problem it solves is "we know that the Earth can't move, so how can we describe the motions of the planets". As the Earth can move, this isn't a problem. So the whole ...


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Orbital eccentricities cannot be normally distributed around zero, since the minimum eccentricity is zero. Thus, in the same way that the Maxwell-Boltzmann distribution for particle speeds is zero at zero speed and peaks at finite speed, then no asteroids have exactly zero eccentricity and we would expect a peak at higher eccentricities. The analogy can be ...


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In spherical polar coordinates, one of the coordinates used is an angle between the direction to a point in space and a "pole". Let this "pole" be the ecliptic north pole and call the angle the inclination $i$ (i.e. the inclination is the angle between the direction that the orbital axis points and ecliptic north pole). If lots of ...


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Short answer: The scarcity of asteroids with an inclination near zero is an expected result of normally distributed inclinations in 3-dimensions about the normal vector to the reference plane, rather than selection bias or an orbit "clearing" around zero degree inclination. Long answer: Orbital inclination is typically defined as the angle between ...


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A moon will describe a path like this if its orbital speed relative to its parent planet is greater than the parent planet's orbital speed about the Sun. (Assuming the moon's orbit about the planet and the planet's orbit about the sun are roughly coplanar; I'll ignore Uranus for the remainder of this discussion.) Going through the planets: Neptune: All ...


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