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Fri, January 27, 2012
Number of planets in our solar system is up in the air
By Cliff Sain
From 1930 to 2006, our solar system had nine planets.
Now it has eight.
What happened? Did a planet explode?
No, it was not anything that dramatic. It’s just that Pluto — long considered the most distant and the smallest of the solar system’s planets — was reclassified by the International Astronomical Union. Its name was erased from the list of official planets and, instead, it became what is known as a dwarf planet.
The significant difference between a planet, like Earth, and a dwarf planet, is that the dwarf planet does not have enough gravitational pull to clear its orbit of other objects (either by pulling them in or scattering them away). Pluto, for instance, orbits in what is known as the Kuiper Belt, a region beyond Neptune made up of thousands of icy bodies known as Kuiper Belt objects, or KBOs. They are also sometimes referred to as transneptunian objects.
Five and counting
However, not just any old space rock can be a dwarf planet. To qualify, it must be orbiting the sun, it must have enough mass to take a primarily round shape, and it cannot be the moon of another object.
Right now, there are officially five dwarf planets: Pluto, Makemake, Haumea, Eris and Ceres. Those first four are all KBOs and are sometimes called Plutoids. Ceres orbits in the main asteroid belt between Mars and Jupiter.
Ceres, like the other dwarf planets, is relatively small. In this case, Ceres is even 14 times smaller than Pluto. At its equator, it is 580 miles across, about the size of Texas. Scientists believe Ceres might have a lot of pure water ice beneath its surface, perhaps totaling more than all the fresh water on Earth.
Ceres was discovered in 1801 and initially was considered a planet. As more objects in the belt were discovered, it became known as an asteroid. It was classified as a dwarf planet in 2006 along with Pluto and Eris.
Pluto is about two-thirds the diameter of Earth’s moon, and probably has a rocky core surrounded by a mantle of water ice. Pluto has a moon named Charon, discovered in 1978, that is about one-fourth the size of the planet. Since then, three additional, but very small, moons have been discovered orbiting Pluto. An unusual aspect of Charon is that it orbits Pluto at the same rate that Pluto rotates on its axis, every 6.4 days. That means, from Pluto’s viewpoint, the moon never rises or sets, but stays in the same place.
See "Link to External Source Article" below to read further.
If this article is accurate, this puts the number of planets in our solar system at 13, which is one more planet than The Urantia Book teaches that it has, as in the following section; it seems the jury is still out on the interesting subject.
5,000,000,000 years ago your sun was a comparatively isolated blazing orb, having gathered to itself most of the near-by circulating matter of space, remnants of the recent upheaval which attended its own birth.
Today, your sun has achieved relative stability, but its eleven and one-half year sunspot cycles betray that it was a variable star in its youth. In the early days of your sun the continued contraction and consequent gradual increase of temperature initiated tremendous convulsions on its surface. These titanic heaves required three and one-half days to complete a cycle of varying brightness. This variable state, this periodic pulsation, rendered your sun highly responsive to certain outside influences which were to be shortly encountered.
Thus was the stage of local space set for the unique origin of Monmatia, that being the name of your sun's planetary family, the solar system to which your world belongs. Less than one per cent of the planetary systems of Orvonton have had a similar origin.
4,500,000,000 years ago the enormous Angona system began its approach to the neighborhood of this solitary sun. The center of this great system was a dark giant of space, solid, highly charged, and possessing tremendous gravity pull.
As Angona more closely approached the sun, at moments of maximum expansion during solar pulsations, streams of gaseous material were shot out into space as gigantic solar tongues. At first these flaming gas tongues would invariably fall back into the sun, but as Angona drew nearer and nearer, the gravity pull of the gigantic visitor became so great that these tongues of gas would break off at certain points, the roots falling back into the sun while the outer sections would become detached to form independent bodies of matter, solar meteorites, which immediately started to revolve about the sun in elliptical orbits of their own.
As the Angona system drew nearer, the solar extrusions grew larger and larger; more and more matter was drawn from the sun to become independent circulating bodies in surrounding space. This situation developed for about five hundred thousand years until Angona made its closest approach to the sun; whereupon the sun, in conjunction with one of its periodic internal convulsions, experienced a partial disruption; from opposite sides and simultaneously, enormous volumes of matter were disgorged. From the Angona side there was drawn out a vast column of solar gases, rather pointed at both ends and markedly bulging at the center, which became permanently detached from the immediate gravity control of the sun.
This great column of solar gasses which was thus separated from the sun subsequently evolved into the twelve planets of the solar system. The repercussional ejection of gas from the opposite side of the sun in tidal sympathy with the extrusion of this gigantic solar system ancestor, has since condensed into the meteors and space dust of the solar system, although much, very much, of this matter was subsequently recaptured by solar gravity as the Angona system receded into remote space.
Link to External Source Article
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