Planet formation Definition and 18 Threads

After googling for many hours I am still not understanding why the formation of rocky planets shall be restricted to protoplanetary discs. Why can't they form from dustclouds far away from any star? Agglomeration should still happen over time. Jeans criterium should not play a role since it is...

Hi - having come up blank when searching, I figured I'd ask here: do you know of any (free, preferably open source) planetary accretion models/simulators available for download? I'm primarily looking for solar system formation / evolution rather than planetary geochemistry (although I'd have an...

Let me be more specific: I'm needing some source that talks, in a more broad way, about how heavier elements tend to "sink into the core" during Earth's formation (when we're talking about siderophile elements, that readily combine with molten iron). Wikipedia's page about the Goldschmidt...

All of the planets should have individual orbits, and should be between the mass of Mercury and Mars. What can their orbits be in AU's? Is there a way to find out how close they can be without destabilizing each other? If we assume the star is about the same size as Sol.

This i know sounds like a really odd question, but thinking along the Lines that i am.. i guess it has a sense of validity. Could it be Possible, that Planets exist with Dual cores that internally orbit inside a Planet.. or partially joined. Thinking along the lines of Cell structure and how...

First, may I apologize in advance if this question is in the wrong section of the forums. Given a cloud of mixed gasses and rocky material, how is spin created when a star is born? I will also give the cloud of gas a random order of movement prior to star formation. Can the physics for the...

I understand that it's possible to calculate the age of terrestial planets through radioactive dating their soil. However, the gas planets present a different challenge since we cannot currently land on them. Any ideas on how to calculate their ages in a different manner?

On the recent news announcement that finds a mismatch in the heavy-to-regular water ratio on 67P found by the Rosetta mission and Earth's oceans, I wonder if the passage of time has been considered? Could the several billion years that comets have been exposed to radiation have increased their...

I understand how conservation of momentum leads to planet formation and planet rotation. However, after studying this model, I have ran into a point of confusion that I cannot find the answer to: Why don't the planets collapse into the sun just as dust particles collapsed inward via...

In the first part of Brian Cox's documentary series 'Wonders of the Universe', he explains how the entropy of the universe always increases, and that we are therefore headed for a state of total 'disorder' where all is left of the universe is photons and dying black holes. But wasn't this...

Is it common for rocky planets to form closer to a star and gas planets further? Why or why not is this?

What is the chance of planets forming from gas clouds without a star? has anyone calculated this? are they more likely to form than stars? could there be billions of rogue planets floating arround our galaxy?

For a gas and dust cloud to collapse under gravity to form a star and planets, is the concept of friction important at all? In other words: let's consider a large number of billiard balls, no internal degrees of freedom, participating in completely elastic collisions, with random initial...

When our star the Sun finally accumulated enough matter for fusion to start what would that have done to the planets around it? Afterward what would have happened to the Earth for it to get from when the sun started fusion and blasted the Earth and now, with water and atmosphere?

In a recent theological discussion, I came to realize that there is a point in question regarding planet formation in the current model of the origins of the Solar System. The question itself is not theological, but has some theological ramifications. It goes like this: Planets are believed...

can u help me to explain the role of gravity in the equilibrium of stars in their production of enegry , and an explanation of the role of gravity in the formation of planets. thankssssssss

Has there ever been a hypothesis or theory propsed (current or obsolete) proposing that the rocky planets formed from gas giants whose ring system collapsed and combined with the core of the gas giant forming the bulk of a new rocky planet? Just wondering if this has ever been proposed or...

[FONT=Comic Sans MS] Okay, this is a general question.. i just read this thread (https://www.physicsforums.com/showthread.php?t=28343) and started wondering about it. THis planet is considered "young", and it is a million years old. SO, my question was why does planet formation take so long? i...