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From Kuiper Belt to Oort Cloud
Published in Thomas Hockey, Jennifer Lynn Bartlett, Daniel C. Boice, Solar System, 2021
Thomas Hockey, Jennifer Lynn Bartlett, Daniel C. Boice
Even at Pluto's low temperature, which averages −225°C (−373°F), it has a thin atmosphere. Because Pluto's gravity should be too low to keep hold of gases, its atmosphere cannot have been there very long. Yet, if a world is mostly ice that constantly sublimates, eventually we would have no Pluto! However, Pluto's orbit is quite eccentric, especially compared to the major planets. It is warmer at perihelion than at aphelion 124 years later. Ice turned to gas at perihelion may be refrozen at aphelion and then fall back onto the surface before it can escape. Thus, Pluto has a temporary atmosphere at perihelion.
The Origin of the Elements and Earth
Published in Dexter Perkins, Kevin R. Henke, Adam C. Simon, Lance D. Yarbrough, Earth Materials, 2019
Dexter Perkins, Kevin R. Henke, Adam C. Simon, Lance D. Yarbrough
Astronomers define planets as being massive enough to be rounded by their own gravity but not massive enough to heat their cores to temperatures required for nucleosynthesis. Additionally, planets have sufficient gravity to attract all planetesimals and other debris from the regions around them. A dwarf planet, also called a planetoid, meets the first two-thirds of this definition but has insufficient gravity to clear the area around it of other space debris (Fig. 1.16). Pluto, discovered in 1930, was originally classified as a planet but now has been downgraded to dwarf planet status. The known and named dwarf planets, in increasing size, are Ceres, Makemake, Haumea, Eris, and Pluto. Ceres is the largest body of the Asteroid Belt but is the smallest dwarf planet with a diameter of about 945 kilometers (590 miles). Pluto (2370 kilometers diameter) and Eris (2330 kilometers diameter) are the largest dwarf planets. Some dwarf planets have moons; Pluto has Charon and four other moons. Most of the dwarf planets are much icier than Ceres because Ceres is in the Asteroid Belt (closer to the sun) and the other four dwarf planets are outside the orbit of Neptune. Astronomers will likely discover other dwarf planets in the outermost solar system in the future.
Looking at the Sky
Published in José Guillermo Sánchez León, ® Beyond Mathematics, 2017
We’ve seen that PlanetData doesn’t include Pluto, demoted to the “Dwarf Planet” category in a controversial meeting of the International Astronomical Union on August 24, 2006. This action was motivated mainly by the discovery of planets beyond Pluto, in an area known as the Kuiper Belt that probably includes thousands of planetoids. Pluto is considered to be part of this belt. All the planets that didn’t fit the new definition were categorized as dwarf planets. There are reasons to justify that Pluto doesn’t belong to the same category as the classical planets but the dwarf label doesn’t seem the most adequate one since there are dwarf planets that are most likely bigger than the classical planet Mercury.
An Exploration of Mission Concepts That Could Utilize Small RPS
Published in Nuclear Technology, 2020
Young H. Lee, Alexander Austin, Brian K. Bairstow
Figure 2 gives one example mission architecture concept for a Pluto lander of approximately 70 kg wet mass. The study team used engineering judgment and analogies to prior missions and concept studies to estimate notional technical parameters, given the science goals and instruments identified. This information was then used to estimate the required end-of life (EOL) power output required from the RPS, in this case 10 W(electric). Also estimated was an allocation for the RPS mass and volume allocation that would be available on the lander.
How AD can help solve differential-algebraic equations
Published in Optimization Methods and Software, 2018
John D. Pryce, Nedialko S. Nedialkov, Guangning Tan, Xiao Li
This problem from the non-stiff part of the DETEST testing package for ODE solvers [2], and originally2 from Zonneveld [23], is titled ‘Five Body Problem: Motion of five outer planets about the Sun’. It is a order 2 ODE of size 15 (so size 30 when reduced to order 1), the variables being the positions of Jupiter, Saturn, Uranus, Neptune and Pluto relative to the Sun, in x,y,z coordinates such that the ecliptic plane, in which the orbits approximately lie, is not close to any of the three axes.