Planetary Definition and 306 Threads

The magnetic fields of several planets in our solar system are from what I've read caused by electric currents - does anyone know what the electric currents are caused by?

Homework Statement The radius Rh of a black hole is the radius of a mathematical sphere, called the event horizon, that is centered on the black hole. Information from events inside the event horizon cannot reach the outside world. According to Einstein's general theory of relativity, Rh =...

Hi there, I'm kinda new here, I did a search for similar things and couldn't get anything concrete. I'm starting my Undergrad Project in January, and its on Gas Giant Formation. It involves running lots of code to see how particles in an accretion disk apply themselves to a previously...

Homework Statement Suppose that a human head is a sphere with the bone thickness 10% of the radius of the head. Find the fraction of the volume of the head occupied by the brain. Make a similar estimate (forget about factors of pi) in the N-dimensional space (d = N) in the limit N ->...

theoretically by GMm/r^2 = mv^2/r, planets in a particular distance to the star will move in the corresponding velocity in order to maintain a circular orbit... either over speed they will pass by the star, or under speed they will be attracted towards the star in a spiral way So why are...

Homework Statement Derive the equation using Newton's Law of gravitation and the equation for circular motion. Homework Equations V = \sqrt{\stackrel{GM}{r}} Where G is the universal gravitational constant, M is the mass of the central body and r is the radius...

Dear all, I am interested in the connection between the smoothness of a planet and the gravitational acceleration at the surface. Specifically, what is the highest a mountain can be for different values of g? More pertitently, what % of the Earth's surface would be covered with water if the...

This might be a good idea for a thesis. Could we alter a comet's course and make it break free of orbit and head towards another sun and populate other planets? Some of them are made up of life sustaining elements right? Could we use nuclear power to melt it to create a biosphere?

Homework Statement Two masses, m and M, are initially at rest at a great distance from each other. The gravitational force between them causes them to accelerate towards each other. Using conservation of energy and momentum, show that at any instant the speed of one of the particles relative...

The following question deals with planetary motion: energy totals and binding energy. I have solved the question to the best of my ability, but I cannot get the right answer! I don't know what I am doing wrong, and would greatly appreciate it if someone could point out my mistakes. Homework...

Homework Statement A NASA spaceship is orbiting the moon at an altitude of 111 km. How long does it take the ship to make one orbit around the moon? This was a question on the test I had today, just wondering if I'm out to lunch or not. So he gave us all the info on the moon on an overhead...

Can someone explain keplar's third law of planetary motion to me without the math and not to technically, just what does it mean?

What is the effect (if any) of the sun's movement around the galactic center in relation to planetary orbits?

The mean distance between the Earth and the moon is 3.84x10^8 m, and the moon has an orbital period of 27.3 days. Find the distance from Earth of an artificial satellite that has an orbital period of 8.5 days. a. 1.76x10^8 m b. 1.76x10^4 m c. 1.76x10^10 m d. 5.24x10^8 m So far I got: I...

I was curious as to how planetary type spherical bodies form. Specifically, I was curious as to how the gravity affects the nebulous particles moving within themselves just prior to a solid planetary body forming. Is it not true that gravity is essentially zero in the center of a planetary...

First is the "Blue Snowball", a planetary nebula. I took three pictures tonight. First is the "Blue Snowball", a planetary nebula. This one is really bright and 30 second exposures are all that is really needed. The only stretching that was done was to cut off the black level at the...

How is it possible for one planet to rotate opposite the others and one to rotate 90 degrees axially from the others, and these continue to rotate without stopping?

Homework Statement Two planets A and B, where B has twice the mass of A, orbit the Sun in elliptical orbits. The semi-major axis of the elliptical orbit of planet B is two times larger than the semi-major axis of the elliptical orbit of planet A. What is the ratio of the orbital period...

a) Show that the escape speed for a particle to leave the gravitational infuence of a planet is given by (2GM/R)^1/2, where M is the mass of the planet, R is its radius, and G is the gravitational constant. b) The temperature near the top of Jupiter's multicolored cloud layer is about 140K. The...

Has the existence of a planetary disk condensed as a rigid aggregate ever been postulated or observed?

From http://www.vgg.com/VGGBlog/ End Planetary Discrimination Now! Hello I'm Charon. You might know me as Pluto's "moon." I've remained silent in the planet/not-a-planet controversy regarding Pluto, but I can remain silent no longer. The International Astronomical Union has decided to...

How many planets do we know of that actively have thunder storms? If possible please go into detail about the strength and occurance of these thunder storms on alien planets.

Hi guys Im currently investigating planetary orbits in maths and one of our problems is to prove that Pluto spends a good deal of its time inside the orbit of Neptune. If anyone could help that would be great. Thanks Kyle

To all: By memory I have seen in the literature the factor 1/6 when analytically discussing the retention of a planetary atmosphere (more correctly a particular specie of molecule in the atmosphere). The relation would go something like this: Atmospheric mean thermal speed of molecule <...

I am disappointed and a little alarmed to find big discrepancies between simulator software. Following advice from https://www.physicsforums.com/showthread.php?t=84458", I tried simulating the same date: May 5 1975 with three simulators: http://www.fourmilab.ch/cgi-bin/uncgi/Solar"...

It is said that high massive planets can eject small planets in planetary forming systems. I don't understand that since gravitation is supposed to attrack things. Do you know of any article that expains that kind of phenomenum?

i know that if a star having planets dies, and becomes a black hole the planets continue to revolve around the black hole. how is it possible when the black hole sucks everything??:confused:

hi i hv these 2 doubts...i tried using the elliptic equation: r= a(1-e^2)/[1-e cos(theta)] however i can't really figure out how do i determine the answer,,i mean if i could know what exactly to do. 1) the orbit of venus is very near circular (e=0.0068).Assuming that the orbit is completely...

Hey i was wondering i need to perform 2 experients (i can't do the penulum one) using completely different methods to measure the acceleration due to gravity. I thought of the droping different masses and using the ticky tape timer, ? Also where will i be able to find these things for...

Would someone direct me to a specialist, website or any other way of find out how the planets were aligned on my date of birth. I was born August 03, 1978 at 10:07am. I want a tattoo of all the 9 planets (including the sun and the Earth moon) as they were aligned on my date of birth. Can...

Hello everyone, Its good to FINALLY be back! :biggrin: I was wondering why the path of the planets in our solar system is elliptical and not circular? ~Kitty

which chapters in MATH, PHYSICS and CHEMISTRY are most required for: "Earth and Planetary Sciences"? Joe

Terrestrial planets in general are solid, or solid with a liquid core. Gaseous planets in general are liquid, or liquid with a solid core. Can there be planetoids with substantial alternating layers of solid - liquid - solid, or liquid - solid - liquid? (I do not consider Earth's...

The composition of planetary atmospheres is determined in part by the speeds of the molecules of the constituent gases, because the faster moving molecules can reach escape velocity and leave the planet. What is the R.M.S speed in ms^-1 of the helium species at 325K?

I an trying to calculate the temperature of a hypotethical planet orbiting the CHARA star at a distance of 1 AU. Now I know that the luminosity of Sol is 4x10^26 watts and that Chara's is about 20% more so 4.8x10^26 watts. I found the following equation to calculate it...

Hi for some reason I can't get this easy/hard question. I've tried different things but they are wrong. Please help, here's the question: At a certain point between the Earth and the moon the total gravitational force exerted on an object by the Earth and the moon is zero. If the Earth-moon...

<Hmm. I just realized that this post would be better suited for the "Celestial Mechanics" forum. Would you mind moving this post, since it appears that I am unable to do so myself without posting twice?> To begin with, does anyone know of the confirmed existence of or believe in the...

Is it know why the Earth's core, and indeed the cores of other planets, are "hot" while some are cold? Is it possible that fusion or fission processes are taking place there ?

Help! Planetary motion Please help! Planet X rotates in the same manner as the earth, around an axis through its north and south poles, and is perfectly spherical. An astronaut who weighs 946 N on the Earth weighs 920 N at the north pole of Planet X and only 854 N at its equator. The distance...

I've been thinking about this for a while now, and I was wanting to know what you guys think. The problem states: Show that a projectile with mass "m" can escape from the surface of a planet if it is launched vertically upward with a kinetic energy greater than MgR, where R is the the planet's...

Can someone tell me which is the favoured theory for planetary formation, core accretion or Gravitational instabilities, and if these are the only valid theories?

Hi, When a white dwarf is formed, why do the outer layers of gas which made it a red giant drift away to foirm a planetary nebula? Decrease gravity? Outward pressure? What exactly? Also, when the outer layers of a star move outwards to form a red giant, why do they cool down? (hence...

Avoiding A “Crash Course” In Planetary Defense http://www.space.com/businesstechnology/technology/neo_defense_040310.html

http://www.spaceref.com/news/viewpr.html?pid=13330 To their surprise, the researchers found that in specific cases, the computer calculations suggested that the sphere would change shape dramatically. Frey said these special circumstances, called singularities, might ultimately reveal...

Would it be possible for binary planets, or even a planet and it's moon, to simultaneously sustain life? I know the odds of a planet having life on it is very low, but for a planet that does (earth) would it's sister planet or moon be able to sustain life as well? Maybe if the bodies are the...

Can anyone provide a link or document that compares the properties of the planets? I'm interested in all of the following: mass, composition, density, obliquity, orbital eccentricity, semimajor axis, atmosphere, magnetic field, #satellites, internal heating. I'm also interested in the relevant...

I'm trying to model the possble average world temperature for any given day of the year, for planets at varying distances from a star and composed of multiple materials in different quantities for an online game I'm helping develop. basically each planet's composition is simplified to land...

if a massive body fails to become a star could it still suport planetary system?

i found this page of major observatories,if anyone is interested just follow the links, there is a fantastic amount of data and tools, its all here. http://www.astro.unibas.ch/~parodi/observatories.html ------------------------------------------------------------------- ever wondered...

Are there any pictures of other planetary systems? Are there any close ones? I think I heard a while back of antoher system with planets..