Planets Definition and 509 Threads

Hypothetically this pseudo-Earth suddenly appears and follows the same orbit as Earth, but moves slightly faster. If it eventually collides with Earth at snail pace what would the gravitational effects be like? (maybe ignore the moons)

Homework Statement Suppose that I am jumping on the Earth, and I weigh 130 lbs. I push off with an initial vertical velocity of 2 m/s, and reach my highest height at 4 m. If I were to jump on a different planet with an extra 130 lbs (earth weight) because of a space suit etc., would I have a...

May be this question has been asked multiple times here i was just unable to search it by topic or search term. The Question is if every thing is falling towards the sun (i.e planets). Why planets are not falling towards sun in a spiral fashion and ultimately crash into sun ? This may be...

Hi all, I have just joined this forum to see if anyone here can help me out. First off, I am creating fictional planets that orbit fictional stars. I have given all of my planets a diameter and a distance from their sun. From this, I have managed to calculate their orbital periods and...

I was reading an article over the weekend that the Moon has evidence of a "final" volcano on it's "far side." I am working on something that suggests the Moon would be too small to have had volcanoes, and this didn't fit with my assumption. I then reasoned that based on size, and based on the...

If we only consider the terrestrial planets and moons, do you think the amount of water on Earth is in the top 10%? Or are we perhaps average here? Could it be that the norm for terrestrial planets is to be completely covered with water? And that the Earth is rare in its lack of water...

Backward "orbit" of the planets How do you tell when a planet is going backwards in its "orbit" of the earth? Do you have to plot a graph and pick out the points? There must be an easier way!

Can anyone give me a rough idea of a timescale for first planets in the Universe? I understand that supernovae are required for heavy elements for rocky planets such as Mars or earth, but was wondering if this same requirements would hold for gas giants? Just trying to establish the most...

Why do specific object movement is conditioned by the gravity force? Why the moon is pulled by Earth and doesn`t move freely? Why the planets don`t move in different way but obey to the gravitacional force of Sun? Everybody knows that Earth moves around the sun for 1 year and travels for...

Why is the actual mean temperature of the moon so much lower than the effective temperature? NASA lists the effective temperature of the moon at 270.6 kelvin. The mean temperature of the moon at the equator is 220 kelvin. With no atmospheric effects, why is the surface temperature so much...

I was watching How the Universe Works, and they mentioned that planets were formed by dust particles that came together to form rocks, and that those rocks collided with one another and became larger and larger eventually forming planets. My question is why did the asteroids in the asteroid belt...

there' s a problem that tells " estimate the radius of a planet that a man can escape it's gravitation only by leaping vertically upward..that density of the planet is assumed to be same as earth..." it seems to me that there's not enough information provided here to solve the problem...

Hello, I learned from Yahoo about the existence of many more "rogue planets" than stars. These planets are not bound to a solar system, they are "free floating". I found more information on wikipedia and jpl. I wonder now if these "rogue planets" could be an alternative to the "dark...

Interesting news about planets with no orbit: http://news.yahoo.com/s/ap/20110518/ap_on_sc/us_sci_wandering_planets Perhaps enough mass to explain dark matter?

So I'm not huge when it comes to physics. In fact I only created and account in order to ask this question. I'm am trying to figure out a way to calculate the approximate size of a planet based on how long it's day/night time cycle is. There is a lot of variability involved here. I think I...

Can we know something of the distribution of planets material in general? I mean, the percentage of solid, fluid, gas planets in general (maybe theoretically) in solar systems. And percentage of planets with atmospheres?

Can planets escape there orbit? If so does that mean there are planets in deep space?

This isn't a HW question exactly, but I'm trying to model planetary motion and I've having trouble remembering something I learned a while ago when I took physics. I remember that the tangential velocity for a something to orbit a planet is v = sqrt(-G * M/r), but I need to decompose this...

Why majority of planets move in anti-clockwise direction around the sun??

As we know from gyroscopes, the axis of a spinning object remains in the same orientation. For example, for a spinning object traveling in a straight line, the line of travel we could call a plane and the spin axis in the direction of travel could be perpendicular to the plane and the spin axis...

Homework Statement A binary star system consists of two equal mass stars that revolve in circular orbits about their center of mass. The period of the motion, T = 25.5 days, and the orbital speed v = 220 km/s of the stars can be measured from telescopic observations. What is the mass of...

So at the end of the lengthy thread https://www.physicsforums.com/showthread.php?t=404650", a similar but new question of mine arose: If you consider the Earth rotating, you can measure differences in weight at different points on the Earth (namely, the extremes being the poles and the...

Hello, I'm currently studying general relatively and am trying to plot orbits of planets around the sun using the schwarzchild metric. I've worked out the geodesic equations, working with c=1 to simplify things, and written a MATLAB script to plot trajectories, but I'm struggling to work out...

Homework Statement If there's a satellite(not man-made although I wonder it would matter) is chaotically orbiting around two planets, will it ever cross the same orbital path twice or not? Homework Equations The Attempt at a Solution I think if the system is chaotic, it will not...

Seeing the horn (which is like a water vortex) of General Relativity, it seems that the position of the Sun is at the bottom of the horn and the planets rotating somewhere above. Doesn't that disaggre with Newton's ellipses on almost the same plane? Any link explaining this?

Is there someway to inhabit the giant planets in our solar system? (I don't mean on their moons, but actually on the planet itself).

Unusual paper: http://arxiv.org/abs/1102.1108 Some planets get ejected from their systems and wander off into interstellar space. The authors investigate what would be needed for such a planet to remain able to support ocean-floor life for a protracted period on the order of a billion years.

Homework Statement Two planets are orbiting the sun in elliptical orbits in the same plane. The orbit of planet Q has a semi-major axis of 64.8 AU and eccentricity of 0.445. Planet R has a semi-major axis of 42.5 AU and eccentricity of 0.825. The perihelion point of Planet R's orbit is...

In the Doppler shift or radial velocity method for detecting exoplanets, it is assumed that the orbital period of the star's planetary companion is equal to the period of the star's detected wobble. I'm assuming that this fact comes straight from the solution to the two-body problem. My...

Why are the orbits of planets revolving around a body(say the sun) elliptical rather than circular or any other shape? Please show the answer mathematically.

From "[URL Wikipedia - Earth's rotation[/URL] The angular speed of Earth's rotation in inertial space is (7.2921150 ± 0.0000001) ×10−5 radians per SI second (mean solar second).[11] Multiplying by (180°/π radians)×(86,400 seconds/mean solar day) yields 360.9856°/mean solar day, indicating...

Can there be planets revolving around black holes? I'm not asking about black holes at the center of galaxies, but other black holes.

In our Solar System, how does the ratio of gas planets to terrestrial planets compare with that of gas moons to terrestrial moons?

It certainly seems like it. People are far more excited about Titan than they are about Saturn. And the same is true for several other Saturnian moons. Same with Jupiter and its 4 biggest moons. People seem to care more about its 4 moons than Jupiter itself. I'm no exception. But certainly, I...

why do Planets have elliptical orbits ,why do they just not have circular orbits ,I understand that the sun is like a bowling ball on a sheet of rubber and the planets in our solar system orbit the bowling ball as if i got a marble and rolled it onto the sheet of rubber but after a while the...

Do planets follow the curvature of spacetime as they orbit, or what is their path considered to be?

Is it possible to speed up or slow down the speed of a planets rotation by attaching jet engines (or some other device) along the equator of the planet?

I was wondering if anyone could indicate me towards recent(and respectable) findings over the number of Earth type planets in the galaxy. examples of exoplanet studies and the like would be great. thanks a lot. And also findings on the number of exoplanets surrounding stars would be most...

Homework Statement http://www.its.caltech.edu/~tmu/ph1a/FPs/fp12.htm this is the question. Homework Equations T^2=\frac{4\pi^2a^3}{GM} E=-\frac{GMm}{2a} The Attempt at a Solution I have none. My question is, does the fact that there are two planets affect the equations for period and...

An artificial satellite circles the Earth in a circular orbit at a location where the acceleration due to gravity is 9.00 m/s^2. Determine the orbital period of the satellite.

Homework Statement http://i1046.photobucket.com/albums/b465/laurenwings5/Picture1-1.jpg Two planets with the same diameter are close to each other, as shown. One planet has twice the mass as the other planet. At which locations would both planets’ gravitational force pull on you in the...

1. Homework Statement Mars orbits the sun at a mean distance of 228 million km, in a period of 687 days. The Earth orbits at a mean distance of 149.6 million km in a period of 365.26 days. All answers should be in the range (0, 2pi) a) suppose Earth and Mars are positioned such that Earth...

First post, I am just a layman, so go easy. The way I understand it, the moon is following a straight line through space. However, the mass of the Earth is so great that it warps the fabric of spacetime and it appears that the moon is going around the earth. Same with any moon or planet, they...

The discovery of Eris prompted the creation of the category "Dwarf Planet" for Pluto and some other objects. They said that there would be hundreds of others, but 5 years later, no one has found any more. Is this right? Is the demotion of Pluto based on a mistake? Or did everyone just...

hi, how does general relativity work INSIDE stars and planets, since the mass is no longer concentrated within a point, so there are necessarily gravitationnal effects outwards and not only inwards?

I was wondering if anyone here had experience using the image dataset of the Sloan Digital Sky Survey. Specifically, I want to find images of Mars from within their data. However, because they take one picture of the sky a night, and at a very small section of the sky, it's hard to predict...

Hi, a novice astronomer here. Was just looking at some stars/galaxies/planets the other day, and followed up some observations by looking at their locations (on wikipedia). I noticed that for stars/galaxies there are a range of different coordinate/location systems used, although the...

Starship + 2 different planets? Homework Statement The problem from my textbook is: Inside a starship at rest on earth, a ball rolls off the top of a horizontal table and lands a distance D from the foot of the table. This starship now lands on the unexplored Planet X. The commander, Captain...

I'm toying with the idea of making a little 2D space orbiter game so I've implemented Newton's universal gravity law into this little app. It works really well, even. The problem I'm having is when I want to create an asteroid-belt. I spawn little asteroids randomly around an area around the...

why should the planets rotate?