Planets Definition and 510 Threads

Just a quick question Are the planets totaly locked in there orbits forever or do they slowly get drawn in closer to the sun?either by the sun's gravitational pull or simply by the sun expanding? Thanks in advance for any replys mike

This might sound like an unoriginal question but what is gravity? Why does the Earth and the sun and other planets have gravity? Does everything have gravity? What causes gravity? Thanks ahead of time :smile:

I haven't got an answer to my last post but I've got another question. What gasses are present in the dwarf planets and other larger kuiperbelt objects?Are they simmilar to the gasses in the gas giant?

Quick question, do bigger planet spin faster?

Hello, When I thought about centrifugal force, gravity came into my mind... When we tie a rope around a ball and rotate it in the air, rope gets some tension ( small displacement between atoms of rope ) and we feel this as centrifugal force. This force occurs because we apply an...

How did the planets acquire their spin?

Hi, I'm a bit confused on how in theory one could work out the size of a planet knowing the luminosity of the star it is orbiting and also the drop in luminosity as the planet blocks some of the light from the observer. Wouldn't you have to know the surface temperature of the star to work out...

Is there an equation to predict the distance of a hypothetical planet from it's host star to be locked? (For G, K, M stars)

Hi, I have posted here a few times but lately I think I have been refining my interests somewhat so I want to compare my goals up against the reality. I think I would like to work in a field of study exasolar planets in particular terrestrial ones that may harbor Earth like life. Now some...

I have for a long time now wondered about how the planets and moons actually congealed into their current forms. How can loose mass and gas develop the gravity to pull themselves together? Could the cause of these actions been related from the "big bang" which threw out micro black holes of...

Homework Statement Planet X has five times the diameter and seven times the mass of the earth. What is the ratio gX : ge of gravitational acceleration at the surface of planet X to the gravitational acceleration at the surface of the Earth?Well, I used the equation: \frac{Fplanetx}{FplanetE}=...

From a terrestrial perspective, could Venus have ever eclipsed Mars?

Why doesn't the asteroid belt block our view of the jovial planets? I'm assuming it's because the asteroids are just too few, far apart, and small to affect our view, but I'm not sure and I'd like to know. Thanks!

The solar wind is a stream of charged particles plasma—ejected from the upper atmosphere of the sun. It consists mostly of electrons and protons with energies of about 1 keV. These particles are able to escape the sun's “gravity”, in part because of the high temperature of the corona..so i have...

What is Time according to Physics? And here's a hypothatical situation and question: If the rotation of planets around Sun stops, there won't be any more days and nights, it would stop where it is, but would that mean that time has stopped advancing?

Since Dark Matter is by definition immune to electromagnetic forces, then it has no other way to interact except through gravity -- unless one wants to come up with some entirely new force, which has never been seen. If Dark Matter did have some force of its own, akin to electromagnetism...

What are causing the Eccentricity of the planets? When reaching Neptune we have nearly a completely circular orbit. Why ? It seems not to be any logic in this ! Mercury 0,20563069 Venus 0,00677323 Earth 0,01670900 Mars 0,09340100 Jupiter 0,04849500 Saturn...

Mars orbits the sun at a mean orbital radius of 228e9 m and has an orbital period of 687 d. Earth orbits teh sun at a mean orbital radius of 149.6e9 m. a)The earth-sun line sweeps out an angle of 360 degrees during one earth-year. Approximately what angle is swept out by the Mars-sun line...

I am wondering if there is a source of the magniude of the Dipole moments of all the planets and the sun, m. m(earth) is 8*10^22 A*m^2. The Magnetic Field and the Electric Field such that: Br = Mu0/4/pi*2*m*cos(Theta)/r^3 Btheta = Mu0/4/pi*m*sin(Theta)/r^3 Mphi = 0 Er =...

Have population II stars been observed or speculated to have planets?

In the case of orbiting planets does the True Anomaly(=0) start at the Argument of Perihelion equal to R at R<1*a and at a minimum? And at 180 + Argument of Perihelion equal to R at R>1*a and at a maximum? Is this true?

Homework Statement OK here's the question: What is the period of a planet orbiting 3 A.U. from a star 3 times as massive as the sun? And my teacher says to use keppler's 3rd law revised by Newton but I am completely confused by the equation and how to use it on this problem. Homework...

What is the cause of the planets (and the Suns) rotation

This came up on another website I read, and it got me to wondering, so I am certain someone here could answer this. The sun is constantly losing mass, as it converts its mass to energy. As it loses mass, its gravitational field weakens, because the gravitational field of a body is directly...

I'm working on this project and I've kind of come to a roadblock. Here's a little background: we have a 1 solar mass star and a planet orbiting it. The planet is defined by 5 orbital elements (period, mass, eccentricity, longitude of periastron, and mean anomaly). I wrote a code that will plot...

Looking at planets... Hi, not sure if this is the right area for such a post but... I was just thinking if the Hubble space telescope can see for millions of light years then why can't it look at stars from other solor systems and search for planets and the look at the planet for life? After...

I wonder if it would be possible for some kind PFer to create me a map of the current position of the planets and minor bodies in the SS, (i.e. a map of the SS from above, not from Earth). I guess I'd need one of both the inner and outer SS. I've downloaded all sorts of astronomy apps over...

I heard that all the planets rotate in the same direction(Clockwise) except Venus which rotates in the opposite direction(Counterclockwise). Is this true?

Homework Statement A spy satellite is in circular orbit around Earth. It makes one revolution in 6.00 h. A. How high above Earth's surface is the satellite? B. What is the satellite's acceleration? Homework Equations I'm not sure but I believe we could possibly derive...

Hi, I would like you people to approach these problem of an infinite universe, which contains only three identical objects, say planets of equal volume and mass at equal distance from one another: Scenario 1) They all hover in the sky not moving relative to one another. Are they all...

How come planets don't fall into stars as they orbit them? Einstein said a "space-time" curvature is caused because of the gigantic mass of the stars...why don't the planets orbiting these stars just fall right into them? Does it have something to do with the same reason why electrons never...

How do relativity explain elliptical orbits of planets?

Hey guys, I am no scientist (I am studying advertising at uni), although I am terribly interested in it. My highest scientific learnings was high school; but I did take physics, math c, biology, chemistry. Anyway, I am in no way qualified so my point is bear with me and don't hate ;) I was...

The Earth is effectively an insulator in space, and the sun continuously beats on the Earth with protons, electrons and other particles. Does the planet Earth and all other planets have a net charge, and if so, how can we measure the polarity and extent of that charge? Turning to the Sun...

[SOLVED] Extra-Solar Planets and their stars wobble Homework Statement An extra-solar planet is detected by observing that its parent star had a radial velocity 'wobble' of amplitude 40 m/s. If the parent star has a mass of one Solar Mass, and the period of the 'wobble' is four days, find a...

We started learning about gravitational force and how gravity is different everywhere. But than we talked about circular orbits and how we can find its period and such So to remain in circular orbit the gravitational force between 2 planets pull each other, but doesn't those opposite reaction...

Like the earth, do other planets have magnetism?

I am studying the problem of ice ages and I wonder how do I find, in what form the most modern, "official" data about motion of Earth through space? Presumably this includes data about whole solar system for calculating perturbations. As I understand that set of data should give all...

Heads up! Really cool! :cool: I hope they do both the aircraft and submarine on Titan and Europa. Talk about a design challenge.

ok... why electrons don't get stuck to the nucleus since they are attracted by it? what force stops them ? Why do planets move around the sun but never get close to it? Who gave them initial velocity so they can "fly" in an orbit around a bigger object like the sun. why are orbits...

Homework Statement Two particles of masses M1 = 81000 kg and M2 = 9400 kg are initially at rest an infinite distance apart. As a result of the gravitational force the two masses move towards each other. Calculate the speed of mass M1 and mass M2 when their separation distance is 26.5 km...

Imagining a clock...the middle of the face where the hands rotate from represents the sun. If at 12 and 6 were to planets, could they inhabit the same orbit around the sun without consequence? I imagine they would not collide as they would be moving at the same rate and in this scenario are...

Homework Statement A planet of mass M has a moon of mass m in a circular orbit of radius R. An object is placed between the planet and the moon on the line joining the center of the planet to the center of the moon so that the net gravitational force on the object is zero. How far is the...

Sometime ago, a guy asked about a scenario that if there were another Earth planet opposite to our Earth across the sun, could we identify it. Now, my question is if the two finally would coalesce after some time?

Hello everyone - newbie here. Am I right to say that stars twinkle because of regions of the atmosphere being at different (and varying) temperatures and pressures etc., giving rise to a variation in refractive index and consequently a shifting image of the observed object? If so, why don't I...

Hi all, I just realize that for most of the planets in our solar system, the heavier the planet, the faster it rotates around its axis. Do you think there may be any reasons for that?

Uranus, Neptune, Jupiter, Mars, Pluto, etc.--each of them has either moons or rings. Both rings and moons revolve around their equators regardless of the planets' axis. What concerns me is that while Earth's moon also revolves around the axis of Earth, why is it that during the saros, the moon...

Homework Statement Hi everyone, i was presented with this problem in my Computer Programming for Engineers Class. The orbit of the planets around the sun can approximately be modeled by the polar equation: http://www.prml.org/images/71715equation.PNGThe values of the constants P and e for...

why haven't there been any observations of planets or stars or anything near a black hole's event horizon being distorted?

Im trying to solve (approximately) the following problem: Suppose that i have 2 planets with mass m1 and m2 orbiting around the sun and i take into account the following interactions: a) Interaction between planet 1 and the sun b) Interaction between planet 2 and the sun c) Interaction...