PV Gap

Ann Said:

3.What has led to the information of two different types of planets in the solar system?

We Answered:

The ability of a planet to retain volatile gases is a function of three variables, not merely the two being the star's luminosity and the planet's distance. The third variable is how much mass the planet already has when the star gets hot, or how fast it can acquire more mass if the star is hot already.

Volatiles don't necessarily puff away instantly. They have an evaporation time, t, being roughly...
t = 10^(Ve / Vr) years
...where Ve is the escape speed from the planet's surface and Vr is the rms speed of the volatile in question.
t = 10^{ sqrt[ 2GMm / (3kTR) ] } years
...where G is the gravitational constant, M is the planet's mass, m is the mass of an atom or molecule of the volatile, k is the Boltzmann constant, T is the equilibrium blackbody temperature at the planet's distance from the star, and R is the planet's radius.
t = 10^{ sqrt[ 2GMm / (3kTR) ] } years
T = [L/(16 pi s r^2)]^0.25
...where L is the star's luminosity, s is the Stefan-Boltzmann constant, and r is the distance between the planet and the star.

This equation is MKS, except for t in years.
t = 10^{ [2GMm / (3kR)]^0.5 (16 pi s r^2 / L)^0.125 }

This equation may be more convenient.
t = (17555 years) 10^{ (Mm/R)^(1/2) r^(1/4) L^(-1/8) }
where...
M is the planet's mass in Earth masses
m is the volatile molecular weight in atomic mass units
R is the planet's radius in Earth radii
r is the planet's minimum distance to the star in astronomical units
L is the star's luminosity in units of the sun's luminosity

Let's do a Hot Jupiter Feasibility Study. How long could Jupiter hold on to hydrogen and to helium if it were placed in Mercury's orbit?

t = (17555 years) 10^{ (Mm/R)^(1/2) r^(1/4) L^(-1/8) }
M = 317.8
R = 11.209
r = 0.3075
L = 1
If m = 2 (for H2) then t = 7.11 billion years
If m = 4 (for He) then t = 1.5 trillion years

So diatomic hydrogen would be stable in this hot Jupiter's atmosphere for a time commensurate with the age of the solar system, while any heavier gas would be essentially permanent.

Andy Said:

Is any information obtained from outerspace outside our solar system through telescopes millions of years old?

We Answered:

We've obtained information not just millions of years old but billions of years old. We have observed objects as distant as 13.7-billion light years away from us.

Useful information? I think so, and not just because it gives us info about our beginnings. By looking millions and billions of years back into the past (..at least as far as celestial objects go...) we can better understand what the future might hold for us. For example, we know that the Milky Way and the Andromeda Galaxy are heading for a collision. What's going to happen then? We can get a pretty good handle on the answer by actually studying how other similar collisions between galaxies millions of years ago went off.

Melanie Said:

what other information do you need before you can construct an exact scale model of the solar system?

We Answered:

Well you could start by using a cm. to represent a real distance, then get all your measurements and build it from there.

For example, if 20 cm=1 AU, then you put Earth 20 cm from the sun, and then place the other planets accordingly. Show the orbits in the same relation. etc...

You get the idea.

But then, when you see how far the Jovian planets are from the terrestrials, then try to add the asteroid belt...you may find youve bitten off more than you can chew.

Don Said:

What are primitive meteorites? what kinds of information do they provide about the origin of the solar system?

We Answered:

"Some meteorites have a chemistry indicative of little alteration since their formation (and probably since the formation of the solar system). These are known as primitive meteorites." http://web.missouri.edu/~speckan/witch-s…

Be sure you include the attribution (the link). If you don't it's plagiarism. At best, if the teacher found out, you'd get a 0 for the assignment. Quoting a website and saying that you did is fine.