Solution

 

The Solar Physics Group at NASA's Marshall Space Flight Center was formed in the early 1970's in conjunction with the Apollo Skylab Mission. Some facts about the Sun published by this group are given below:

Solar radius = 695,990 km = 432,470 mi = 109 Earth radii

Solar mass = 1.989 10³⁰ kg = 4.376 10³⁰ lb = 333,000 Earth masses

Solar luminosity (energy output of the Sun) = 3.846 10³³ erg/s

Surface temperature = 5770 K

Surface density = 2.07 10^-7 g/cm³ = 1.6 10^-4 Air density

Surface composition = 70% H, 28% He, 2% (C, N, O, ...) by mass

Central temperature = 15,600,000 K

Central density = 150 g/cm³ = 8 × Gold density

Central composition = 35% H, 63% He, 2% (C, N, O, ...) by mass

1. Convert these temperatures to C and to F

 

C = K - 273.15          F = (9/5)C + 32

 

	Kelvin	Centigrade	Fahrenheit
Surface Temperature	5770	5496.85	9,926.33
Central Temperature	15,600,000	15,599,726.85	28,079,540.34

 

 

2. What are these estimates based on? How are they determined?

 

 

3. Explain a rationale for the center being hotter than the surface.

 

The solar interior is separated into four regions by the different processes that occur there. Energy is generated in the core, the innermost 25%. This energy diffuses outward by radiation (mostly gamma-rays and x-rays) through the radiative zone and by convective fluid flows (boiling motion) through the convection zone, the outermost 30%.

Surface exposed to low temperature of space