Astrophysics/elements in earth
When the heavier elements were formed by nuclear fusion in stars, what made the stars to explode ? When the planets were formed by condensation of the dust particles which were the remnants of the stellar explosion, how did the elements such as carbon, iron got into the planet. Were these elements were in the form of dust particles and got condesnsed into the planet?
Is the below statement made by the author scientifically valid?
"So meteor showers hitting the Earth increased the heat enough to melt that iron, not produce iron, but to melt that iron and it would then sink through the surface towards the center of the Earth and became concentrated in the core of the earth and thatís how they explain it now"
Ugh, I wrote out an answer and it apparently never sent.
To your first question... Novae and Supernovae happen for several reasons, and those are typically the type of explosions that are responsible for forming almost everything heavy in the universe. More about this topic has already been written by expert scientists than I could possibly cover here. Therefore, here's a reference to start you off: http://hyperphysics.phy-astr.gsu.edu/hbase/astro/snovcn.html
It's maintained by experts at Georgia State University. But that's where the iron comes from.
The second part of your question is related to the third, but your statement is better (and simpler/more direct) than the other source you quoted. But they're not as different as they seem at first. As the Earth collapsed, it basically was formed in a non-solid state by the same things it's composed of now. Things settled, lighter stuff ended up on top. Less common stuff formed compounds with more common stuff (like uranium oxides) and probably ended up more on top than stuff that formed homogeneous materials. No one ever said that heat at the Earth's core produced iron, in recent scientific memory (meaning my lifetime, at least). The iron was already in the Earth, when the whole thing collapsed into a volcanic ball...but this story has a twist.
The Earth was hit by something about the size of Mars. This caused a massive fracturing of the planet, leading to the formation of the current Moon. For a planet of its size, Earth's moon is reeeeally large. Only the dwarf planet Pluto has something similar, in our solar system. So that event totally disrupted the distribution of everything in the planet...which had to settle back into a round shape with our tilted axis. Good thing that (presumably) phenomena like convection evened everything out.