Ch-ch-changes

[EnjoyItClem]

As planets migrate toward their sun, what changes do they undergo? Do they: shrink or expand; heat up or cool off; get gassier or wetter or dryer; get more radioactive or less radioactive; get brighter or darker; move higher or lower; spin faster or slower; tilt forwards or backwards? Is it a different tale for a gas giant, a terrestrial planet, and an asteroid belt? Or is it the same for each? I want the story at the peak of the bell curve, please.

[D H]

What makes you think planets migrate toward their sun?

[CaptainPanic]

Little friction slows down planets, which means they get a lower orbit? I'm not sure it can even be measured though.

[Blade]

Little friction slows down planets, which means they get a lower orbit? I'm not sure it can even be measured though.

 

http://www.talkorigins.org/indexcc/CE/CE110.html

 

http://hypography.com/forums/astronomy-cosmology/13668-dark-matter-causes-moon-receding-earth.html

 

Dark matter causes moon receding and earth’s rotation slowing?

 

dark matter (read: placeholder for broken newtonian gravity) might explaint why the universe is expanding and the expansion is speeding up.

[D H]

Little friction slows down planets, which means they get a lower orbit? I'm not sure it can even be measured though.

 

Drag was a factor in the very early solar system. This is what accounts for the extra-solar jovian planets that orbit at incredibly close distances to their parent sun. Our solar system escaped this problem; the planets cleared almost all of the junk from there paths. There is nothing left in the solar system to cause such drag today. There is a tiny amount of drag with the solar wind, but that is immeasurably small. Solar radiation pressure (which is directed outward) is a much, much bigger effect, and even that is incredibly small.

 

http://hypography.com/forums/astronomy-cosmology/13668-dark-matter-causes-moon-receding-earth.html

dark matter (read: placeholder for broken newtonian gravity) might explaint why the universe is expanding and the expansion is speeding up.

There is no need to invoke dark matter in explaining the Moon's recession from the Earth. Conservation of angular momentum using simple Newtonian gravity does the trick. Invoking dark matter begs the question: Why then isn't the Earth receding from the Sun?

 

Newtonian gravity is broken? Newton gravity does fail in regimes of very high velocity (Mercury's anomalistic precession) and very large masses (black holes). NASA still uses Newtonian gravity to plan and operate space missions. It works quite fine in regimes of non-relativistic velocities and smallish masses. The Moon's velocity with respect to the Earth (1/300,000 c) and the Earth's gravity field are both quite small.