Planetary Definition and 290 Threads

This watch uses a novel geartrain fixed to a lunar-phase display wheel which is supposed to rotate once per synodic(lunar) month. More precisely, it should rotate once every 29.530589 days. The geartrain is described in detail and the explanation claims it achieves an accuracy of once every...

Hello everyone, I hope somebody can assist me with this. I am working on a calculation for a planet gear with 4 sun wheels and 1 planet wheel. The aim is to determine the forces on the sun wheel. Initially, I have 3 equations and 4 unknowns. By making an assumption based on symmetry, I now have...

I was reading about the Tusi couple and read it "as a solution for the latitudinal motion of the inferior planets, and later used extensively as a substitute for the equant". Since the Tusi couple is related to plotting out an ellipse, did Nasir al-Din al-Tusi already discover the laws for...

TL;DR Summary: Solar sytem forces on Unity Hello ! For my last year in my school, I've got a project to do, and I wanted to recreate the Solar system with forces on Unity. My forces are Velocity and Acceleration (I'm using the Frenet's formulas). I'm sorry I'm not a physicist and that's why...

I was running a simulation in Universe Sandbox where I placed a 10 million solar mass black hole about 10 light years from the Solar System, initially stationary relative to the Sun. I noticed once the Sun had reached about 70km/s relative to the black hole, all the orbits became wavelike rather...

An article came up on Phys.org about a white dwarf drawing in material from the planetary system surrounding it. Is this the ultimate fate of our solar system? https://phys.org/news/2022-06-dead-star-cannibalism-planetary-far-reaching.html...

Hello. I'm writing my Master Thesis about planetary population synthesis and one of the chapters is about the different models. I found that most of them are Bern models with some modifications. What is a Bern model in planetary population synthesis and what references can I read about it...

https://www.feynmanlectures.caltech.edu/I_09.html 9-7 "From this figure we see that the horizontal component of the force is related to the complete force in the same manner as the horizontal distance x is to the complete hypotenuse r, because the two triangles are similar. Also, if x is...

Looking East this morning about 5:15 am. No telescope needed. But the pic is not actual - it is from Stellarium.

Summary:: Writing a YA Space Opera series, but I'm lost on trying to create a formula for calculating "Earthbirth Days" Short run down: Earth was no long hospitable to humans so we left to colonize a new planet, Nemesyne. People on Nemesyne still celebrate their "Earthbirth Days" and count...

I am looking for a modern review article on high pressure equations of state and planetary interiors. Preferably post 2010. Does anyone know of one? Thanks.

I'm very much an amateur with a keen interest in space/the universe and it occurred to me the other day that our solar system could have been formed in exactly the same way that it is hypothesised that the Moon/Earth system formed through the (proposed) collision of Theia and the proto-Earth...

Hi, I need a little help with this problem with compound planetary gears. I don't know how to apply the formulas for this specific type of placement. I need to know the final speed of the engine knowing the number of teeth z1 = -104 ring gear which is internal, z2,3,4 = 22 for small planets...

Hi I am confused about certain aspects of deriving the planetary orbit equation by considering it as 2-body problem. I will ask my first question now before i get to my other questions. In the David Tong notes on "Dynamics & Relativity" he states that a particle in central force potential...

I read this interesting article today, the original paper here. Abstract:

Hi I am a computer science undergraduate working as a data scientist. I generally love studying physics and planetary science. I am aspiring to research in biomarkers and bio signatures in planets. If I have to choose this research path should I study masters in, astrophysics or...

The answer to (c) is ##-2\pi AGMm##. Answer to (d) For sub-question d, I used a different approach and I don't know why the solution to (d) is an appropriate approximation. What I did was that I use Newton's laws to obtain two differential equation in polar coordinate, as shown: $$\text{Assume...

Hi there, I'm a research scientist having worked in various fields and institutions, I'm now out on my own as an independent contractor. I don't have my computer guy down the hall to ask computer questions to, or the building of experts to quiz when I'm stuck on a problem. I also miss helping...

Why is it that all of the planets in our solar system (to our knowledge) orbit the sun in such a way that they all go around the sun in roughly similar orbital planes? Why don’t we have planets with orbital planes at significantly different angles?

Mars apparently does not have a molten core, therefore no magnetic field. If Mars had a substantial moon, say Ceres, would the tidal action melt the core in Mars? And, perhaps, allow Mars to retain an atmosphere.

Hello all, In a planetary gear system, there is: sun gear planet gear Ring gear Carrier Suppose the SUN gear delivers the input torque to the system. (I do not care about the planet gears in this system.= There are two torques that can result. The ring can deliver a torque and the carrier...

Homework Statement: The particle is moving in circular orbit such a way that the net force (F) is always towards the point p (point p is on the circumference of circle). Find the variation of force F with respect to r. i.e find the value of n in the expression F=kr^n Homework Equations: F=kr^n...

What is/are the potential or theoretical effect on electricity due to reversal of planetary magnetic field? Would circuitry continue to function or would knowledge and understanding need re-evaluating as a result of a reversal of our magnetic field on planet Earth? Note: this is not a homework...

Does anyone have any research material for up to date research about these planetary boundaries? https://www.stockholmresilience.org/research/planetary-boundaries.html

Hi. Currently I’m 17 and I’m coming to the end of my first year of A levels. I have to start writing my ucas and applying for unis later this year. I’m really interested in space and have always wanted to go down that route, however I’ve not had much guidance as what to do with my future in...

Many asteroids and planets have undergone enough heating so that they were at some point completely or partially melted. What physical mechanisms are in play here? I'm assuming a solar system such as our own. Thanks!

The 6th Annual International Academy of Astronautics Conference on Planetary Defense ended this past Friday. I watched about half of the presentations. I have little astronomy background but was interested in what was being done about NEO detection, characterization effects and mitigation...

The age of the oldest rocks on Earth & Moon are about 4.5 Gy old. But doesn't the material that made the Earth come from the supernova that had occurred prior to the formation of the Solar System, and doesn't the radioactivity dating measure the age of the creation of that material in that...

If, as suspected, the Andromeda galaxy "colides" with our own sometime in the far future, would the gravitational forces from passing stars have effect on our solar system? In accelerated models the interaction looks quite violent, but how would it be in our "uncharted backwaters of the...

https://phys.org/news/2019-01-planetary-collision-moon-life-earth.html The claim is that was how the excess Carbon, Nitrogen, and Sulfur arrived in the Earths crust, without them being in the core. For instance the Carbon/Nitrogen ratio of 40/1 is twice the 'expected' value.

I'm curious as to how the mass of a body affects the kind of atmosphere it can hold. I know that Earth tends to lose its lightest gases over time, which is one reason why helium doesn't build up in the atmosphere, whereas planets like Saturn and Jupiter have held on to lots and lots of hydrogen...

The thought of increasing a satellite's (for example) speed to allow it to transfer from a "higher energy" elliptical orbit to a "lower energy" circular orbit (in reference to the effective potential energy plot that arises after introducing the concept of an effective mass to simplify the...

Hi - having come up blank when searching, I figured I'd ask here: do you know of any (free, preferably open source) planetary accretion models/simulators available for download? I'm primarily looking for solar system formation / evolution rather than planetary geochemistry (although I'd have an...

I'm looking to calculate the ratio of a planetary gear train. With the ultimate goal of producing a spreadsheet/calculator to show the state of the gearbox (i.e. all shaft speeds) based on applied constraints. A gear set consists of Ring Gear, Planet Gear, Sun Gear. The sick diagram is the...

Are there any good theories which can explain how the orbits of planets are not aligned with the rotation of the Sun? I gather there is about 6 degrees of differance, which is not small.

Hey, this is how i tried solving the differential equation The solution however does not match the general solution of the equation. Also differentiating it twice does not give me the previous equation. Please tell me if i did some mistake while solving. I already know how to solve by finding...

Does anybody know who first drew (not just described but actually drew, even roughly) a model of the atom like the one below, and when: I'd appreciate it if anybody can point me to an evidence.

I am recent undergraduate with a B.S in Astrophysics. I was looking at getting a PhD in planetary science, but curious what type of industry jobs are available. I'm not interested in working in academia.

Hi, I found some back of envelop calculations which show that Jupiter accounts for over 60% of the solar system's angular momentum. http://www.zipcon.net/~swhite/docs/astronomy/Angular_Momentum.html Is that correct? A previous thread here on the subject ( now locked for some reason ) claimed...

Hello, I am completing a research project for differential equations class. I am to derive Kepler's three laws and then compare the results of the derivation with real-world data. For Kepler's second law (a planet sweeps out an equal area in an equal time), I was hoping to find orbital data for...

Homework Statement What is the tension of this rope? Cosmonaut m=100kg is outside of spaceship M=5 tons on rope with length 64m. Cosmonaut along with his spaceship moves in orbit at a neglible distance. m=100kg M=5000kg L=64m Planet's mass 6*10^24 Planet's radius 6400km Homework Equations...

How does one correct for tidal forces when (classically) simulating the orbits of solar system bodies?

Hi all, I'm an undergraduate Physics major looking to jump into Planetary. Through either a reasonably priced subscription, or free, and in paper or online, what would you suggest as a journal or professional level news aggregate for me to get the latest updates and literature in planetary...

Homework Statement A comet with a perihelion distance of d = 1.242 is currently 211(degrees) from pericenter, and 4.499 AU from the Sun. Compute the semi-major axis a of this comet’s orbit. Homework Equations P(^2) = a^3The Attempt at a Solution I tried to use Kepler's third law but I don't...

So I've found the following formula for calculating the gear ratio of a planetary gear. Tr Turns of the ring gear Ts Turns of the sun gear Ty Turns of the planetary gear carrier R Ring gear teeth S Sun gear teeth P Planet gear teeth ( R + S ) ×Ty = R × Tr + Ts × S The example I saw on the same...

Homework Statement Consider a particle moving in the potential U (r)= -A/r^n, where A>0. What are the values of n which admit stable circular orbits? Homework EquationsThe Attempt at a Solution I tried to solve by putting dr/dt=0 in the total energy equation E= T + Ueff. But it didn't work...

1. Why is Earth's South Pole called its North Pole? Why hasn't it been changed to make it more scientifically accurate? 2. Why are the North Poles of other planets defined relative to Earth's 'North' Pole? Why isn't it based upon the actual direction of the planet's magnetic field?

There will be a new Planetary Protection Officer soon and changes could be happening at the Planetary Protection Office. The office makes rules concerned with potential contamination of planets with earthly life. This Science news article goes over issues (on both sides) that the office is...