Planet Definition and 821 Threads

In our Solar System, what is the best example of a planetary moon having its own satellite? What general properties do such satellites share?

Take a small bh say 100 sol masses, how long would it take to ingest a Earth size planet?

Homework Statement The density of a certain planet varies with radial distance as: ρ (r)= ρo(1- αr/Ro) where Ro= 3.98 x 106 m is the radius of the planet, ρo= 4980 kg/m3 is its central density, and α = 0.17. What is the total mass of this planet ? Calculate the weight of a one kilogram mass...

what you think, do we want to sent probe to Newly discovered planet 'Kepler-22b' now?. the data may be useful after may be a millinium later since it is 600 light years far away. still it is better now than later, right? or may be we want to wait for quantum entanglement in quantum information...

And not just define but be able to detect the essential components of our definition. I find sentences like the above quoted from here, to be annoying because from what I understand it is misleading and trivialises science for the general populace who on the whole have no conception of...

I think about this every time I look up at the stars and think about the fact that what we're seeing is the sky as it existed X years ago, depending on how far away the star is. So let's say we're traveling toward a planet at near light speed, do you watch it age at a rate relative to the time...

Homework Statement The weigh tof spaceman speff, soley due to the gravitational pull of planet x at its surface is 389N. If he moves to a distance of 1.86*10^4km above the planets surface his weight changes to 24.31N. What is the mass of planet xif speffs mass is 75 kg. Homework Equations...

Sorry about the less-than articulate title, but I was defeated by the thread-title character limit. The title of this three was to have been: "What's the Advantage of a Sun-and Planet Gear Setup over an Eccentric Rod and Driver Wheel Setup?" The eccentric rod-driver wheel setup seems to...

Homework Statement Consider a planet in some solar system which has a mass double the mass of Earth and same density as of Earth . What is the weight of object on the planet in terms of 'W' , where 'W' is weight of object on Earth Homework Equations W=mg ... density = M / V . ...

Homework Statement The mass of one planet in a distant galaxy is 0.58 that of the Earth's mass , and its radius is 0.57 that of the Earth's radius. What is Fnew, the factor by which the man's weight is reduced if he were orbiting the planet at a distance of 3.5 Earth radii above the...

Why do we have only one sun and moon on planet Earth , while there are more than one sun on other planets ? Is there a possibility that one day in the future we might have another sun or moon on planet Earth ?

hi experts i know stellar evolution but how planet like Earth is formed and how it has heavy elements does it is the remanant of supernova?

Homework Statement Suppose that we see a planet in our Solar System that we measure to have an orbital period (around the Sun) of 18.0 years. We look at it with a telescope and see that it has a moon. From repeated observations, when the planet is near or at opposition, we note that...

Homework Statement The gravitational pull of the Earth on an object is inversely proportional to the square of the distance of the object from the center of the earth. At the Earth's surface this force is equal to the object's normal weight mg, where g = 9.8m/s^2, and at large distances, the...

Homework Statement The Earth is 6371km in diameter and this is equivalent to 1 mass. If I increase the Earth's mass to 2x what will be its diameter? What is the formula to compute this?Homework Equations The Attempt at a Solution PS: This is my first post and I wish to say hello to everyone!

Homework Statement Big anaconda orbiting the planet XYZ-123 in a vertical position (along the radius of the planet and at a constant height). At some point, anaconda folded her in a small bundle. Is its orbit will be circular? He begins to recede from or approach the planet? 2. The...

Title says it all. Could a planet exist which is completely liquid water? How about an ice core and water surface?

Homework Statement A particle travels in a parabolic orbit in a planet's gravitational field and skims the surface at its closest approach. The planet has mass density ρ. Relative to the center of the planet, what is the angular velocity of the particle as it skims the surface? Homework...

Homework Statement The most energy-efficient method of getting a spaceship from one planet to another is via a Hohmann (transfer) orbit. The ship's launch is aimed in such a way that the perihelion and aphelion of the ship's orbit is tangent to the circular orbits of the two planets and timed...

Homework Statement Measuring the flux of a star as a function of the time, the flux exhibit a decrease of 1.65% for 2h 56m, periodically every 57.22 days. Such decrease is ascribed to a planet transit. The continuous spectrum of the star is like a black body with T= 9500 K, and its...

Just got this in my e-mail today: Hurray for more possible planets! For those unfamiliar with Planet Hunters, see the FAQ here: http://www.planethunters.org/faq

Hi all :) Hope the day has been good to you...i am stuck on a question for my uni assignment, and have been stuck on this one for about 3 days to no avail...i don't even know where to start. I'm not too sure whether i need a certain equation for the question or if i have to come up with one...

https://www.youtube.com/watch?v=74mhQyuyELQ Reference: http://www.youtube.com/watch?v=74mhQyuyELQ"

see http://slatest.slate.com/posts/2011/09/16/kepler_16b_nasa_discovers_planet_with_two_suns_like_tatooine_in_.html

NASA says that the case of Kepler 16-b is "the first unambiguous detection of a circumbinary planet." But Wikipedia lists at most five circumbinary systems: PSR B1620-26, HW Virginis, Kepler-16, DP Leonis, and NN Serpentis. If so, why is Kepler's discovery the FIRST if four systems were already...

Basically I'm wondering how big a rock in space would need to be to draw an average person to it with a gravitational force of a kilo or two. Say it was the average density of Earth and it was spherical, what would its diameter be.

http://fastcache.gawkerassets.com/assets/images/8/2011/09/xlarge_hd85512btop.jpg HD 85512 b Reference: [PLAIN]http://en.wikipedia.org/wiki/HD_85512_b"

Homework Statement Been working on this for the past hour or so and seem to be going in circles; finally decided to call in the cavalry: You land on an unknown planet somewhere in the universe that clearly has weaker gravity than Earth. To measure g on this planet you do the following...

Like can whatever is happening inside, tsunamis, earthquake, volcanic explosion, hurricanes, the sky ripping apart, or just any natural disasters that all happen at the same thing and the planet cannot contain the chaos and explode? I mean stars can, why can't planets?

http://news.cnet.com/8301-17852_3-20097817-71/astronomers-weve-found-a-planet-made-of-diamond/" I have absolutely no prediction about this thread, and with the cast of regulars we have here at PF, am hoping it will generate some funny, interesting discussion. Pengy, Jimmy, Evo, Lisa are you...

So let's say we have a planet not too dissimilar in size to those in our Solar System. It doesn't have to be spherical. But let's say we want a river to flow round the object. We want the flow to last as long as possible. We can consider two cases seperately: in our Solar system...

https://www.youtube.com/watch?v=ylGwsIIyZf0 Reference: http://en.wikipedia.org/wiki/PSR_J1719-1438"

Okay, so planets in the Goldilocks zone are far enough from the star that it's less likely they are tidally locked. But assuming such a thing exists - shouldn't the habitable zone be wider if the planet is tidally locked to its star? At one extreme, the planet would have an Antarctica-sized...

http://en.wikipedia.org/wiki/Sudarsky_extrasolar_planet_classification Several astrobiologists I know aren't aware of it. Could it just be that someone made a Wikipedia article out of research that isn't widely known yet?

A little over a year ago, I came upon the idea that the eccentricity of Mercury's orbit around the sun creates a tremendously oscillatory solar gravitational force (essentially, massive "solar tides"), which ripped the tectonically dying (now tectonically dead) planet apart.* It also included an...

I started to wonder how would look like a planet similar to the Earth but with ocean level higher by a kilometre or two. I know that it should make climate milder and more humid. I have however a geological question - would such water level affects continental plates? Should I assume: a)...

Homework Statement The weight of an object of mass 1kg at the surface of Mars is about 4N. The radius of Mars is about half the radius of Earth. Estimate the ratio: mass of Mars/Mass of Earth Homework Equations The Attempt at a Solution The answer is 0.1 but I don’t see...

Homework Statement A satellite is in orbit just above the surface of a spherical planet which has the same radius as Earth and the same acceleration of free fall at it's surface. Calculate: i) Speed ii) Time for 1 complete orbit. Radius of Earth = 6400km or 6400000m and accel. of free...

I've been reading about terraforming and really stuck with it. Which planet /moon has the most convenient conditions, such as mass, magnetic field, gravity, intensity of sunlight for possible terraform. Venus, Moon or Mars or some else? Which one do you think? And would it be possible? Basic...

The Subject matter is all over the World facing Energy problem, So I am trying to Explain an idea for Old & New Dams / Reservoirs Hydro electric projects Civil Design Geometry Can be modifying in Architectural Transition to increase our energy potential. Because we are Losing heavy quantum of...

I want to know if, say mother earth, could be moved? How much energy would have to be applied to push a planet closer to it's sun or futher away? Also which force would more likely to move such a mass?

in my book i think that on any planet if we can stay for 1 year then on Earth how much time are gone

I wrote a program in java to simulate gravity in 3 dimensional space between any number of objects, and i wanted to test if it works. i managed to find the data for the Earth and the sun and tried those out and the sun acted as a slingshot for the earth. i would like to know if i could find...

I've been posing this question to physicist folk for 10 years, mySpace 6 years ago, and here (don't know when, when I had an older account), and I see that others bring it up on occasion. I will refine it to meet current objections. You have a photonic drive spaceship. It has a (classical) mass...

Hey all, I saw this this (..) morning. :) http://www.cosmosmagazine.com/news/4321/first-habitable-exoplanet-confirmed 20 light years away, can have water and an atmosphere. What do you guys think? Is this a legit claim? (I hope this isn't old news that's been posting days or weeks...

Hi, not sure if this belongs here or Astrophysics or... ?? http://au.news.yahoo.com/amazing-stories/a/-/article/9454275/could-exoplanet-be-a-haven-for-life/" , planet Gliese 581d. Sorry if this is old news, though the report is in today's Yahoo news here in Oz. They say the planet...

Homework Statement 9. A simple pendulum on Earth has a period of 6.0 seconds. What would the period of this pendulum be on Jupiter, if the acceleration of gravity on the surface of Jupiter is 26 m/s2 A. 2.3 sec B. 3.7 sec C. 6.0 sec D. 15.6 sec Homework Equations T=2pi * sqrt...

Considering that most of the planets are opposite to us, excluding Saturn and Pluto, could that have anything to do with major earthqauke in the last couple of years? Just a thought.

I was hoping someone would give some advice on the development of this entry on calculating the heat received by newly discovered planets. It is pretty much all there, I guess it just need some clean up for forum quality standards: https://www.physicsforums.com/library.php?do=view_item&itemid=601

Hey guys I'm looking for some good reading material on the following extrasolar planet detection techniques (not sure if there are any other...) Radial velocty Transit monitoring Microlensing Detection of IR thermal emission Direct Imaging. Basically I'd like to read about what these...