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Questions tagged [planetary-formation]

Questions about the processes, theories and evidence for the formation of planetary bodies.

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What is the nature of “rock vapor” in this description of the formation of the Moon?

The NPR News item MacArthur Fellow And Planetary Scientist Sarah Stewart Discusses How The Moon Was Formed and audio podcast begins: Ari Shapiro, Host: Sarah Stewart likes to think about what ...
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Can a donut-shape planet or star be formed?

How stable is that configuration and under what conditions such object may form ? Is there any evidence suggesting that such objects might exist ?
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Endogenous Theories For the Origin of Earth's Water (Dry/Wet Accretion?) [duplicate]

I have really two questions: what evidence is there in favour that the majority of Earth's water formed with the planet. what evidence is there that the majority of water did not form with the Earth.
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Are rogue planets ever born in isolation?

I'm using the term "rogue planet" here loosely to mean anything of planet-level mass that is not orbiting around a star. Popular discussions of these objects always describe them as forming around a ...
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Earth is getting more massive by the day?

How much mass did Earth accumulate over time or since just before the dinosaurs? In this physics stack exchange question, the comments argued the answer was incorrect. Also, the mass lost is mostly ...
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How was Jupiter formed

Two days ago I went to a mathematics conference where there was a paper presented on Jupiter's formation via the disk-instability model. I know that there are two different theories for the formation ...
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Is there any planet out there which is half gaseous and half rocky ? is this possible?

I have heard many times that this planet is gaseous like jupiter this planet is like super earth like rocky planet etc. so is there any planet which is mix of gase and rock ?
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How did the lighter elements end up in the center of the solar system? Solar System Formation

The previous generation of stars famously are the origin of all the heavier elements (up until iron?) in the solar system. So a big portion of the solar system mass actually is made up of Carbon, ...
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Why are rocky and small planets nearer to the Sun whereas big, gas giants are farther?

Planets, including Mercury, Venus, Earth, and Mars are rocky planets and are small compared to gas giants. And all these planet are near to Sun. But mass is directly proportional to force. So why don'...
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Kuiper belt planet formation

There are a lot of objects of different sizes in the Kuiper belt. Are objects in the Kuiper belt stable? Is there any chance in the future that one of the larger objects would accumulate enough ...
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Why does the axial tilt & the rotation speed of Saturn & Jupiter vary so much?

I have seen Jupiter and its 4 largest moons in a telescope, several times. The moons are always aligned in a line. This is fine. Very interesting. But.. in case of Saturn, not only that we can see its ...
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The most feasible hypothesis about Theia

The formation of the Moon had many hypothesis over the years, most of them involving a Mars-sized body called Theia, which presumably collided with the Earth. But even within the Theia hypothesis, is ...
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Is there any theoretical or empirical research about planetary systems with a black hole in their center?

I assume such a system would be hard to detect due to a lack of radiation, at least if the vicinity of the black hole does not contain a lot of mass which falls into it over time, thus creating (a lot ...
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If a rocky world is large enough (not a gas or ice giant) can it have helium from the primordial disk in its atmosphere?

When planets are formed do only gas and ice giants accrete hydrogen and helium? Does this accretion have to be beyond the "snow line"? In other words, would all hydrogen or helium in the atmosphere ...
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Why Only Saturn Has Visible Rings

It may be surprising to know that all four giants in our solar system have rings orbiting around them. Yet only Saturn has a system of rings visible to the naked eye. Why is that? What's so ...
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Hydrogen and oxygen in space

chemistry tells us that when mixing hydrogen and oxygen the result is an explosion and water. my question is: does this happen on astronomical scale? for example, did they ever observe planet-size ...
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Are planets more likely to have dense materials at their cores?

When planets are forming, does the densest material sink the core and the less dense material "float" on top? What I'm asking is that are the more dense materials more likely to appear in the core ...
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What stabilizes rings or accretion disks?

We think, more or less, that our Moon was formed from an accretion disk caused by a Mars-sized impactor. Cool. Tidal forces can break apart a moon, causing rings. Ashes to ashes, dust to dust: the ...
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Why do rocky planets form?

When a star system forms from a cloud of gas and dust, why doesn't the dust migrate towards the centre of gravity with the gas to form a star? Why does dust in the accretion disk aggregate to form ...
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How close can planets form to one another?

With the NASA announcement today regarding the discovery of a system containing seven earth-sized planets (3 within the habitable zone), I wondered about the seemingly crowded conditions. What ...
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What does Gauss' divergence theorem say about compression of a body under self-gravitation?

Below this question there is a comment that caught my interest: First, there's a misconception. Compressing a body does not increase the force of gravity on outer-lying masses. That's Gauss's ...
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Age of a planetary body

We quote that the Earth is about 4 billion years old. However earth started with billions of cigarette smoke sized particles. What event or size or something do we use to say this is the start of ...
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Formation of “hot Jupiters” before star ignition

I'm watching a BBC special on the formation of solar systems, and they're covering the topic of "hot Jupiters" that exist near their host stars. The prevailing theory, according to this 2015 special, ...
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What could be the possible origin of boron found in the Martian soil if not from ancient groundwater?

In a recent observation reported in the ScienceAlert article 'Boron has been detected on Mars for the first time" reporting that The Curiosity rover has found boron on the surface of Mars, ...
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Are the “extinct species” of meteorites originally from the “Barbarian” asteroids?

I've asked earlierin this unanswered question about an "extinct species" of meteorite, now I've just read in Phys.org about Barbarian asteroids: Named after the first asteroid of this type ...
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What is meant by the bifurcation of hydrostatic equilibrium shapes in planetary formation?

An intriguing comment below this question links to this Quora question and points to the answer by Robert Walker. The sentence that particularly intrigued me is: It turns out that there are two ...
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Ceres is spherical, Vesta isn't – is it the largest non-spherical solid body in the solar system?

I was showing a recent video about Ceres to a friend and we looked up asteroids. Ceres has attained a fairly spherical shape, but Vesta still has a way to go. From Wikipedia: Vesta's shape is close ...
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Why don't we have in-between planets?

The planets in our system are most often grouped into two categories: Terrestrial: Mercury Venus Earth Mars Gas Giants: Jupiter Saturn Uranus Neptune Why is it that we don't see "in-between" ...
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What is the origin of the dust near the sun?

In this question I asked about the Solar Probe Plus mission. Reading a 2008 report I saw that there is an elevated exposure to high velocity dust near the sun. I understand the high velocity, anything ...
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What other “planetary formation mechanisms” exist beyond “gravitational collapse”?

My curiosity was pricked by the an edit made to this post: What's the distinction between "planetary formation mechanisms" and "gravitational collapse"? sadly the edit was ...
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What's the distinction between “planetary formation mechanisms” and “gravitational collapse”?

As I was curious about the exact identical comment to my title here: https://astronomy.stackexchange.com/a/16135/10102 And as it seems no one asked it yet, I'm simply interested in the difference of ...
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How did the Earth come to be in orbit around the sun?

I'm not sure if this post should be in the physics subject forum, but this seems to fit here too. I have been reading a book about chemistry and how the universe came to be with the theory of stars ...
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How large (that is, radius) could a planet be?

I know that normal planets don't get any larger than Jupiter (or 2 Jupiter radii if hot), as adding more gas just increases density, not radius, until you reach the point of being a brown dwarf star. ...
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Reclaimed bodies in planetary formation?

This question on Worldbuilding.SE got me thinking... We currently think that many bodies that condensed during star/planet system formation, and many bodies are ejected. I've heard it stated that ...
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How the magnetic field and the rotation of the planets and the sun inside our planetry system are related

Coming from this question Are there collected data about the direction of rotation of black holes and the direction of the magnetic field? I want to know: How the magnetic field and the rotation of ...
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Why do planets tend to rotate in the same direction although they have formed from tumbling asteroids?

The axial tilts of asteroids seem to vary randomly (let me know if this premise is wrong), while the planets have a strong tendency to rotate in the same way. If planets were formed by colliding ...
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Do planets migrate suddenly or gradually?

Current models of the configurations of the planets conclude that Neptune once migrated outwards. AFAIK this refurbishment came about by Jupiter and Saturn gradually getting into and leaving a ...
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Ejected planets during the early stages of the formation of the Solar System

This is similar to a previously asked question, but I am just asking about theory rather than observational evidence. Assuming there were a much larger number of protoplanets in the early Solar System,...
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Do the terrestrial planets form later than gas giants in our solar system?

Sorry I forgot where this statements come from, but I also remember the reason behind it is due to young Jupiter moves inwards and destroys the original super earth in inner solar system, and the ...
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How did Mars come to have a 24 hour 39 minute day?

Mercury rotates three times for every two revolutions around the Sun, apparently due to a gravitational resonance with the Sun.Venus takes about 225 days to rotate, and rotates in the opposite ...
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How do proto-planetary nebulae gain momentum?

currently I am curious about proto-planetary nebulae. At first I was curious about how planets spin but I read in a couple of articles that they got their spin from when they were in a proto-planetary ...
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Do most planetary systems have fewer planets than the solar system?

It is my impression that most planetary systems have, at most, three to four planets. Is that real? Or is it just that we lack the ability to detect most planets?
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How can you determine the initial volume of a planet's atmosphere?

Since the surface pressure of a planet is determined by the mass of the column of gasses above it one would surmise that to determine the pressure you must know the volume and mass of the atmosphere. ...
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Lack of planets in the Oort Cloud

With the current news about the possibility of a planet in the Oort cloud, I was thinking, why is the matter in the Oort cloud distributed so? It makes sense that inside the planet region there is not ...
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Orbital resonances and position of planets

I am interested in quick generation of planetary systems for programs similar to Space Engine or Pioneer Space Simulator. As far as I understand, formation of planets is a complex process and the ...
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Is there any way a planet could form independent of a star?

I just recently heard that there are currently no theoretical models that support planet formation without a star, but I can't remember where. So, I thought I would request all of your expertises. ...
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What's special about Saturn that it has distinctive rings?

This may overlap with other questions, but I'm asking what is unique about Saturn in location, properties, etc that is has far more pronounced rings? It's between Jupiter and Uranus and Neptune in ...
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Maximum and minimum gas giant & ice giant densities

I'm working on a star system generator for a game; I'd like its results to be plausible but they needn't be super-realistic. I've got the orbital distances and masses of each body in the system, and ...
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Why, in the Solar System, all the mass seems to be concentrated at the centre?

Is this a consequence of planet formation in accretion disks ?
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Star System Formation questions

I'm making a game in which I'd like to randomly generate star systems. Which is cool. The trouble I'm having is working out exactly what limits I need to place on the generation. So far, the ...