This is the third book in the series that included 'The Theory of Nothing' the "The Universe Revealed.' My purpose in this new book is to more fully explain how science is actually done and how science fits into our culture along with religion and p...
Everyone knows about Pluto, the ninth planet that was recently demoted to a dwarf planet. The reason given for this rather unpopular decree was that there are lots of other objects out there that are the same size as or even larger than Pluto.
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So, what sort of dwarf planets have been found beyond the orbit of Neptune, which are objects that orbit at a greater average distance than Neptune? Currently (Feb. 2017) there are over 2300 discovered objects out there. All of these minor planet objects have a perihelion greater than 30.1 AU, which is the perihelion of Neptune.
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The most massive trans-Neptunian object is Eris. This minor planet has a radius of 1163 kilometers (Pluto's is 1188 km). Pluto is larger but its mass is less. Eris has a semi-major axis of 67.78 AU, whereas Pluto's is 39.48. This means that Eris is much further out from the Sun than Pluto.
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Makemake is the next most massive after Pluto. Its mean radius is 715 to 739 km. The next in line is Haumea with a radius of 816 km.
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These are based on what has been discovered. There might be much larger objects that have as yet gone undiscovered, mainly because they are further out from the sun.
What are these minor planets like?
The easy answer is that they vary in shape, color and composition. The two main materials are ice and rock, but there is evidence of organic compounds and metal. In fact, several trans-Neptunian objects resemble comets, which also vary as to the amount of ice to rock.
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Another classification for these objects is the centaurs. These are more like asteroids and have irregular shapes and some are more like comets. Centaurs have very elliptical orbits that often cross the orbits of the gas giants. Some centaurs, such as 10199 Chariklo, 2060 Chiron and 54598 Bienor are possible dwarf planets. All centaurs are considered minor planets.
The spectra of these trans-Neptunian objects vary all over the place. They indicate mixtures of methane and ice as well as carbon dioxide and methanol. Tholins, which are mixtures of ice, amorphous carbon and organic macromolecules, are often seen in these spectra. There are four types of tholins. One common constituent is methane. Other compounds include ethane, methanol, and water ice.
Since these objects are so far away, they are difficult to observe and, consequently, to determine their sizes. One thing is certain. They are very cold, which means that they exhibit very low blackbody radiations-around 60 micrometers in wavelength, and can only be observed in space using the Spitzer Space Telescope.
Frankly, I'm surprised that they've discovered that many of them. The wild thing about this is they have only scratched the surface, so to speak, of what's out there. It proves that we know very little about our solar system, especially out beyond Neptune.
