Inclination to Eccentricity

Inclination to Eccentricity

Wikipedia provides a List of Gravitationally Rounded Objects of the Solar System from which 23 entries could be deemed to be a planet of some description or another [Planets, Dwarf Planets and Most-likely Additional Dwarf Planets].

Gravitationally Rounded Planets
Note: Data augmented from the Wikipedia entries for the individual objects.

Inclination vs AU

The planets visually divide into three groups.

Low Heliocentric Inclination – Low Eccentricity Planets

Low Inclination – Low Eccentricity Planets

The maximum Heliocentric Inclination for this group is 7.25 degrees.

The grouping indicates the orbits of the Dwarf Planets Ceres and Quaoar are governed by the same mechanics that drive the traditional grouping of eight planets.

Ceres (minor-planet designation: 1 Ceres) is the largest object in the asteroid belt, which lies between the orbits of Mars and Jupiter.

It is composed of rock and ice, is 950 kilometers (590 miles) in diameter, and comprises approximately one third of the mass of the asteroid belt.

It is the only dwarf planet in the inner Solar System and the only object in the asteroid belt known to be unambiguously rounded by its own gravity.

It was the first asteroid to be discovered, on 1 January 1801 by Giuseppe Piazzi in Palermo, though at first it was considered a planet.

50000 Quaoar (“Kwawar”) is a large Kuiper belt object with one known moon.

It is probably a dwarf planet.

Quaoar was discovered on June 4, 2002 by astronomers Chad Trujillo and Michael Brown at the California Institute of Technology, from images acquired at the Samuel Oschin Telescope at Palomar Observatory.

The earliest prediscovery image proved to be a May 25, 1954 plate from Palomar Observatory.

High Heliocentric Inclination – High Eccentricity Planets

High Inclination – High Eccentricity Planets

The minimum Heliocentric Inclination for this group is 9.90 degrees.

The maximum Heliocentric Inclination for this group is 21.76 degrees.

This group appear to be planets embedded in the Kuiper Belt between 30 and 50 AU.

The Kuiper belt, sometimes called the Edgeworth–Kuiper belt, is a region of the Solar System beyond the planets, extending from the orbit of Neptune (at 30 AU) to approximately 50 AU from the Sun.

The Kuiper belt is quite thick, with the main concentration extending as much as ten degrees outside the ecliptic plane and a more diffuse distribution of objects extending several times farther.

Overall it more resembles a torus or doughnut than a belt.

Kuiper Belt

High Heliocentric Inclination – Extremely Eccentric Planets

Extreme AU

This group of extreme AU planets are said to be highly eccentric Scattered Disc objects.

The scattered disc (or scattered disk) is a distant region of the Solar System that is sparsely populated by icy minor planets, a subset of the broader family of trans-Neptunian objects.

The scattered-disc objects (SDOs) have orbital eccentricities ranging as high as 0.8, inclinations as high as 40°, and perihelia greater than 30 astronomical units (4.5×109 km; 2.8×109 mi).

These extreme orbits are believed to be the result of gravitational “scattering” by the gas giants, and the objects continue to be subject to perturbation by the planet Neptune.

Although the closest scattered-disc objects approach the Sun at about 30–35 AU, their orbits can extend well beyond 100 AU.

(225088) 2007 OR10 is a very large planetoid located in the scattered disc.

It is the largest known body in the Solar System without a name.

It is approximately the size of Haumea, and appears to be a dwarf planet.

2007 OR10 was discovered by California Institute of Technology astronomers as part of the PhD thesis of Meg Schwamb, who was at the time a graduate student of Michael E. Brown.

It is currently 87.0 AU from the Sun.

This makes it the second-farthest known large body in the Solar System, after Eris (97 AU), and farther out than Sedna (86.3 AU).

Eris (minor-planet designation 136199 Eris) is the most massive dwarf planet known in the Solar System, and the ninth most massive body known to directly orbit the Sun.

It is estimated to be 2,326 ± 12 kilometers (1,445.3 ± 7.5 mi) in diameter, and 27% more massive than Pluto, or about 0.27% of the Earth’s mass.

Eris was discovered in January 2005 by a Palomar Observatory-based team led by Mike Brown, and its identity was verified later that year. It is a trans-Neptunian object (TNO) and a member of a high-eccentricity population known as the scattered disk.

Eris has an orbital period of 558 years.[14] Its maximum possible distance from the Sun (aphelion) is 97.65 AU, and its closest (perihelion) is 37.91 AU.

(229762) 2007 UK126, also written as (229762) 2007 UK126, is a scattered disc object (SDO) with a bright absolute magnitude of 3.7.

This makes it probably a dwarf planet.

It has been observed 73 times over 11 oppositions with precovery images back to 1982.

90377 Sedna is a large planetoid in the outer reaches of the Solar System that was, as of 2012, about three times as far from the Sun as Neptune.

For most of its orbit it is even farther from the Sun than at present, with its aphelion estimated at 937 astronomical units (31 times Neptune’s distance), making it one of the most distant known objects in the Solar System other than long-period comets.

Sedna’s exceptionally long and elongated orbit, taking approximately 11,400 years to complete, and distant point of closest approach to the Sun, at 76 AU, have led to much speculation about its origin.

However, it is possible that these are Inbound Objects aka Long-Period Comets.

Non-periodic comets (or long-period comets) are comets that do not have confirmed observations at more than one perihelion passage, and thus generally have orbital periods of 200 years or more.

They include single-apparition comets that pass through the Inner Solar System only once.

Non-periodic comets are on near-parabolic orbits that will not return to the vicinity of the Sun for hundreds or thousands of years – if ever.

(Some use the term non-periodic comet to refer exclusively to comets that will never return to the vicinity of the Sun.)

Sedna has the longest orbital period of any known large object in the Solar System, calculated at around 11,400 years.

Its orbit is extremely eccentric, with an aphelion estimated at 937 AU and a perihelion at about 76 AU, the largest perihelion of any known Solar System object until the discovery of 2012 VP113.

When it was discovered it was 89.6 AU from the Sun approaching perihelion, and was the most distant object in the Solar System yet observed.

Even as Sedna nears its perihelion in mid 2076, the Sun would appear merely as an extremely bright star-like pinpoint in its sky, 100 times brighter than a full moon on Earth (for comparison, the Sun appears from Earth to be roughly 400,000 times brighter than the full Moon), and too far away to be visible as a disc to the naked eye.

So keep track of Sedna if you plan to be around at the end of the century for the reason that it is an Inbound Object with a diameter of about 995 ±80 kilometres and it is not a highly eccentric planet with “an aphelion estimated at 937 AU” because:
a) Its Heliocentric Inclination of 4.68 degrees is below the Eccentricity Threshold.
b) The heliosphere only extends to 121 AU.

Voyager 1 became the first spacecraft to cross the heliopause in August 2012, then at a distance of 121 AU from the Sun, although this was not confirmed for another year.

Gallery | This entry was posted in Astrophysics, Catastrophism, Solar System. Bookmark the permalink.

2 Responses to Inclination to Eccentricity

  1. Pingback: Inclined to Push and Pull | MalagaBay

  2. Pingback: Axial Tilt – Game Over | MalagaBay

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