CALCULATION OF EPHEMERIDES FROM INITIAL VALUES

Calculation of ephemerides of planets and comets from initial value

Extensible simulation of planets and comets

The aim of this research was to create an extensible simulator that will not only calculate the trajectories of planets and comets using a numerical method, but be able to graphically simulate them. The significance of this project is its ability to be a useful tool to computer scientists, astronomers, and physicists by determining how an arbitrary set of celestial bodies interact with one another. It allows definition of bodies that belong to a system, and creates a graphical simulation of them based on their specific properties. Ideas are then easily conveyed not only to colleagues, but to the public as well through the simulation. The most interesting feature of this tool however, is its extensibility over time. Those scientists who wish to extend this tool can do so by incorporating different numerical methods, gravitational functions, or more detailed algorithms describing behavior of a certain body or force

Sublimation-induced orbital perturbations of extrasolar active asteroids and comets: application to white dwarf systems

The metal budgets in some white dwarf (WD) atmospheres reveal that volatile-rich circumstellar bodies must both exist in extrasolar systems and survive the giant branch phases of stellar evolution. The resulting behaviour of these active asteroids or comets which orbit WDs is not well-understood, but may be be strongly influenced by sublimation due to stellar radiation. Here we develop a model, generally applicable to any extrasolar system with a main sequence or WD star, that traces sublimation-induced orbital element changes in approximately km-sized extrasolar minor planets and comets traveling within hundreds of au. We derive evolution equations on orbital timescales and for arbitrarily steep power-law sublimation dependencies on distance, and place our model in a Solar system context. We also demonstrate the importance of coupling sublimation and general relativity, and the orbital consequences of outgassing in arbitrary directions. We prove that nongravitational accelerations alone cannot result in orbit crossing with the WD disruption radius, but may shrink or expand the orbit by up to several au after a single pericentre passage, potentially affecting subsequent interactions with remnant debris and planets. Our analysis suggests that extant planets must exist in polluted WD systems.Comment: Accepted for publication in MNRA

About God in Newton's correspondence with Richard Bentley and Queries in Opticks

In Newton’s correspondence with Richard Bentley, Newton rejected the possibility of remote action, even though he accepted it in the Principia. Practically, Newton’s natural philosophy is indissolubly linked to his conception of God. The knowledge of God seems to be essentially immutable, unlike the laws of nature that can be subjected to refining, revision and rejection procedures. As Newton later states in Opticks, the cause of gravity is an active principle in matter, but this active principle is not an essential aspect of matter, but something that must have been added to matter by God, arguing in the same Query of Opticks even the need for divine intervention. DOI: 10.13140/RG.2.2.16732.4416

Isaac Newton on the action at a distance in gravity: With or without God?

The interpretation of Isaac Newton's texts has sparked controversy to this day. One of the most heated debates relates to the action between two bodies distant from each other (the gravitational attraction), and to what extent Newton involved God in this case. Practically, most of the papers discuss four types of gravitational attractions in the case of remote bodies: direct distance action as intrinsic property of bodies in epicurean sense; direct remote action divinely mediated by God; remote action mediated by a material ether; or remote action mediated by an immaterial ether. The purpose of this paper is to argue that Newton categorically rejected the types of direct action as the intrinsic property of bodies, and remote action mediated by a material ether. Concerning the other two types of action, direct through divine intervention and mediated through an immaterial environment, Newton has repeatedly stated that he does not know the exact cause of gravity, but in both cases, he has directly involved God, directly in the first case and as the primary cause (the environment/ether being the secondary cause) in immaterial mediated action. But since recognition of direct distance action could have given some credit to those who thought gravity could be essential to matter, and hence to atheism, Newton never openly acknowledged the possibility of such an idea. Keywords: Isaac Newton, action at a distance, God, gravity, gravity law, gravitation CONTENTS Abstract Introduction Principia Correspondence with Richard Bentley Queries in Opticks Conclusions Bibliography DOI: 10.13140/RG.2.2.25823.9232

Planetary submillimeter spectroscopy

The aim is to develop a comprehensive observational and analytical program to study solar system physics and meterology by measuring molecular lines in the millimeter and submillimeter spectra of planets and comets. A primary objective is to conduct observations with new JPL and Caltech submillimeter receivers at the Caltech Submillimeter Observatory (CSO) on Mauna Kea, Hawaii. A secondary objective is to continue to monitor the time variable planetary phenomena (e.g., Jupiter and Uranus) at centimeter wavelength using the NASA antennas of the Deep Space Network (DSN)

A white paper on dusty plasmas

Dusty plasmas is the name given to plasmas heavily laden with charged dust grains which together with the surrounding ions and electrons constitute a kind of plasma regime. This field of study is receiving increased attention because of the observation of dust during recent spacecraft missions to the planets and comets, together with the dawning recognition that the evolution of dusty plasma clouds in space may be quite different from that of nondusty clouds. Recent work in this field is reviewed and recommendations are made on the kind of research that is needed in the immediate future

Newton on action at a distance

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