Planetary Definition and 290 Threads

Here is a special feature in Nature outlining the state of ten biophysical systems crucial for humanity to thrive on Earth. http://www.nature.com/news/specials/planetaryboundaries/index.html

Homework Statement Hi I am doing a report for a space science class, and i have a theoretical planet that orbits a star 1.07solarM 1.05solarR 6000K, then planet is distance 1.08AU, a period of 400days, temp of 12.85degC and radius of 1.98earthM... Is it at all possible to find the planets...

So, the moon goes around the earth, the Earth orbits the sun etc... Are the orbits eventually decaying orbits? That is, given enough time, will the moon hit the earth, Earth go into the sun etc...?? Is that why galaxies are spiralling?

Does anyone know the inclination of each planetary orbit (in degrees) with respect to the plane of the Sun's equator-plane?All planetary inclinations are known with respest to the ecliptic, and the ecliptic's inclination is known with rescpect to the Sun's equator (7.25 degrees). Such data...

State Keplers laws of planetary motion. The motion of a planet about the Sun, assumed to be fixed at the origin, may be approximated by r''= -ur^(-3) r for u=y ms, where y is the universal gravitational constant and ms is the mass of the Sun. Derive the energy equation for this system...

Hi all, I'm working on a problem where I have to find the time it takes for a planet to form from a protoplanetary disk, using the equation: t = \frac {3}{A}M^{1/3} Where A= ( \frac {(1+2\beta)\sigma}{P}) (\frac {3\pi^2}{4\rho_m})^{2/3} However, I'm not sure which units the...

I want to know the difference between the 2 types of rotations shown in the picture attached . planetary orbiting are similar to the second figure in the picture attached , all i want to know what is the difference between the 2 figures .

Can someone briefly explain to me how Kepler's law of planetary motion uses differential calculus? I'm searching for a topic for a 7 page report on a mathematical concept that uses differential calculus. I thought about Kepler's law on planetary motion, but I have a very vague understanding on...

At first, scientists found stars with planets and think that there are suns with planetary system. But it seems now that every sun has planets. My questiion is are there any suns without a planet.

This is something I thought about while drifting off to bed last night. Immediately after the period between the big bang and the formation of planets, how did these newly created planets enter their respective orbits. I'm assuming the planets had different masses and that this was a...

Hello, Ive got a problem in MATLAB and have searched the internet a lot for help with this but nothing really addresses my issue specifically.\. I wish to use the ode45 solver to calculate and plot the orbits of all the planets in the solar system. I can manage just fine to get them to go...

Suppose you have a star of mass M and a planet of mass m orbiting around it. The orbit is circular. m<<<M. U of course is -GmM/r^2. E of course is going to be -U/2 and kinetic energy U/2 due to the virial theorem. What would happen if the mass of the star suddenly doubles? This is...

Homework Statement A satellite is in a circular orbit very close to the surface of a spherical planet. The period of the orbit is 2.50 hours. What is density of the planet? Assume that the planet has a constant density. R= radius G= gravational constant = 6.6742x10^-11 M = mass of m =...

*THIS IS AN ACTUAL QUESTION, NOT A WHAT IF SCENARIO* I just wondered if it has ever happened or could ever happen that all of the planets align? I'm not saying there are any consequences thereof, just want to know if it's realistically possible, why/why not. Basically just because I think it...

If an object rotates in zero gravity, it generates a small gravity outwards, right? Now, howcome planets attract objects? It doesn´t make any sense! /Andy

Over in another forum I've got myself in trouble by suggesting that theoreticians haven't paid enough attention to this question. George Jones has kindlyhttps://www.physicsforums.com/showthread.php?p=2100856#post2100856" that the question seems to have been answered along the lines of...

I just need an explanation of a formula, and I think part of it is wrong, so here is the formula: (T_A/T_G)^2=(R_A/R_B)^3 so T is the period and T_A is the period of planet A then below it is what I think is wrong, T_G G is the Kepler's constant, I'm not sure what that really is =...

Energy required to "fracture" a planetary mass I was playing around with the Impact Effects calculator at http://www.lpl.arizona.edu/impacteffects/ and doing some thinking about the impact event scenario of the Moon's creation. The main bulk of the Earth seems to have stayed in one piece after...

Ok I got most of them but am having trouble on a few of them. The question is: The Sojourner rover vehicle shown in the sketch above was used to explore the surface of Mars as part of the Pathfinder mission in 1997. Use the data in the tables below to answer the questons that follow. Mars...

All rocky planetoids are born as balls of molten magma, and take millions of years to cool, crust over, & solidify. As a rule-of-thumb, a planetoid's Cooling Time (tcool) scales as its Surface Gravity (g): t_{cool} \approx \frac{Heat}{Dissipation Rate} \approx \frac{Mass}{Surface Area}...

Ok. Let me start off by saying I don't believe 2012 is the end of everything. :smile: However, I have heard about this "planetary alignment" that is suppose to take place. Apparently, scientists have said that either they don't know what affect this will have on us, or that everyone is just...

Homework Statement "Yoda has just discovered planetary system consisting of star Dagobahr and its two planets: Rool and Krau. Planet Rool has average orbital radius 1.6 times as big as planet Krau. If planet Rool orbits Dagobahr in 2.9 Earth years, how long is a year for the resident of...

Consider a pair of binary stars with a separation of 3.60E12 m and an orbital period of 2.55E9s. Assuming the two stars are equally massive, determine the mass of each. keplar's law... so I rearranged the formula and set (2pi*r)/T=sqrt((GM)/r), and then I solved for M, which gave me the...

Compare the orbital speeds of satellites that orbit at the following altitudes. (a) One Earth radius above the surface of the Earth (in km/s) (b) Two and a half Earth radii above the surface of the Earth. Here is the equation to be used, orbital speed is v=(sqrt)(GM/r) G is the...

Does anybody have a list of the positions and velocities of all major objects in the solar system at the same time? (i.e. at Jan. 1 2000 12:00 AM, Earth was here compared to the sun, and moving with this velocity, and Jupiter was here, and the sun had this velocity, etc?) I recently wrote a...

Homework Statement a 9.9*10^23 kg planet orbits a star in a circular orbit. The planet is 5.6 AU away from the star and has an orbital velocity of 32 km/s. What is the mass of the star. (1AU = 1.496*10^11m) Homework Equations G Mp Ms / r^2 = Mp V^2/r The Attempt at a Solution Ms...

Homework Statement The sun rotates around the center of the milky way galaxy at a distance of about 30,000 light years (1ly= 9.5*10^15m). if it takes about 200 million years to make one rotation, estimate the mass of our galaxy. Assume that the mass distribution of galaxy is concentrated...

Homework Statement Given: G = 6.67259 × 10^−11 Nm2/kg2 Two hypothetical planets of masses 2.5 × 10^23 kg and 7.8×10^23 kg and radii 3.2×10^6 m and 7.1×10^6 m, respectively, are at rest when they are an infinite distance apart. Because of their gravitational attraction, they head toward each...

Just curious as to how someone may determine what orbital distances are "safe" or "stable" for planetary interactions? or How close could two planetary bodies get before the gravity interaction destroys one or the other? i.e. Jupiter's Io's orbit places it close to Jupiter, and most of...

https://www.physicsforums.com/showthread.php?t=245558 The attached table shows polar satellite (MSU) atmospheric temperature patterns posted on UAH covering 29.5 years. Note the LT contrast between the north polar and south polar regions, a 1.3 oC rise vs. a 0.2 oC loss. While the northern...

Homework Statement Planets X & Y travel in circular orbits around the same star. The ratio of the radii of their orbits is 5:2. 5 years after the planets were aligned, planet x has rotated 92.6 degrees. how many degrees has y traveled in the same amount of time? Homework Equations...

I know this is technically a planetary science question rather than astronomy but this still seemed like the best forum to ask it in. Do we know why planets have magnetic fields? Does it have anything to do with conductive matter content or ferrous / metallic content? Do purely silicate...

Planetary Society Names Winners of $50,000 Asteroid Tagging Competition http://www.planetarysociety.org/about/press/releases/2008/0226_Planetary_Society_Names_Winners_of.html I'm sure this will make the news periodically over the next 21 years.

"On each planet in a planetary system of an odd number of planets, there is an astronomer observing the nearest planet. Assume the distances between each pair of planets are all different. Prove that there is at least one planet that is not being observed by any astronomer." This seems...

Hey guys, I'm working on this n-body planetary system simulation and I was just wondering if anyone was familiar enough with the Runge-Kutta(RK4) approximation method that they understood how to apply it to approximating the velocity and position of a planet as it orbits around some central...

Why do the elliptical orbits of the planets in our solar system rotate on a single plane.

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...