Submitted by GeoGeoGeoGeo t3_yf5p66 in science
Are the planets all the same relative age? If so it would make sense.
Well yes and no. They all formed roughly around the same time, but if we believe the massive impact theory, earth was essentially REformed some time later
Oh interesting, I hadn't heard of this one yet.
Yes you have its called the moon
No, I haven't. Seeing the moon doesn't mean I've heard the theory stated above. That would be really weird thing to lie about.
It seems like that was a joke that relies either on prior knowledge on deductive reasoning, though with how Reddit typically operates, I get why you’d feel defensive.
Just for clarification, the person you replied to is basically saying that the reformation-causing “massive impact” jettisoned pieces of debris out into space, some of which became the moon. Which is to say, even without actually understanding the theory, you are aware of its effects.
In short, no one’s calling you a liar. But seeing the moon does mean you’re familiar with the end result of Massive Impact Theory, even if you didn’t know that’s what you were looking at.
That doesn't mean you've heard of it before tho. :v which is the problem, I was told, specifically, yes I have heard of it before. I had not.
Idk what to tell you except that jokes aren’t meant to be taken literally. I tried my best to explain the intent/humor of the joke, but it’s possible that it’s just not your type of humor. Or maybe there’s a language barrier.
> I was told specifically, yes I have heard of it before
You were told a joke.
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Hey, I thought it was a funny way to reference the theory. Sorry they thought you were attacking them.
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I haven't heard of this one. Thank you for this, I would enjoy reading these soon :)
We don't know for sure, but was assume they all formed around 4.5-4.6 billion years ago. They where spinning around in a giant debris cloud collecting more and more material and slamming into each other until we had what we see today... or something like that.
So that means they are potentially made up of significantly different materials, perhaps like seams of materials in a mine the cloud was not likely to be evenly distributed and it's hard to say what's really on the inside. It's not like the planet are just blobs ejected from the sun that just happened to turn out that way, much of what they became is based on how they spun around that early cloud of debris and what they run into or what ran into them.
The bigger a protoplanet got the more stuff it could suck in until it was a planet and it was big enough to even absorb smaller planets and protoplanets or get absorb.
It was a game of absorb or get absorbed until they carved the relatively empty space you see today.
The average density of mars is about 70% that of earth. so we'd expect that its made of relatively less metal than earth and more light elements like carbon, oxygen, and silicon. (this is complicated somewhat by compression, but you can do some complicated modelling which suggests that Mars is indeed a slightly different composition than the Earth (its more similar to the Moon)
Are the planets largely less dense as you get further away? Like the elements were light enough to make it further out in larger quantities? Considering it’s rocky planets, then gas planets, it seems that way. I’m sure there’s a huge margin of error when taking material accumulation and how those materials interact with one another to then make larger atoms, especially the more massive planets.
The closer you get to the sun -- or in this case, the protostar that became the sun -- the hotter it gets. Obviously. That's important because it means that when you're close to the sun, it's too hot for many molecules to stay solid, and they'll evaporate (or rather, sublimate). It's very difficult for forming planets to accrete gases, so planets that form close to the sun will generally be denser.
Outside a certain radius, it will be cool enough for water to form ice, and the average density of solid material will plummet. The moons of the gas giants, and Kuiper Belt objects like Pluto are much less dense than Earth because they're made of much more water than Earth, by mass. Planetesimals in this part of the solar system can even grow large enough to start accreting the gases in the forming solar system and grow to incredible masses.
Of course, formation is not the end of the story. Our solar system is not static, and the planets can radically change their position with time. There are many examples of Jupiter sized exoplanets that orbit their stars further in than Mercury!
If you’re further in than mercury you would have a good chance of being tidally locked right?
I wonder about mercury too since it has like no crust compared to the earth. I had heard one theory that mercury had a big collision and it stripped away most of that crust. Sucks mercury is so hard to get to. I wish we knew more about it.
It's more to do with size, as smaller bodies will loose their heat to space more rapidly than larger bodies. However, even this assumption has led to some surprises. The moon, for example, was once thought to be solid - far too small to retain any heat today - but recently was found to have a fluid outer core and mantle with partial melt. Ultimately, as magma rises due to its buoyancy relative to the surrounding mantle rock, the moon may actually become volcanically active in the future if the partial melt continues to rise upwards through its mantle before it solidifies.
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