ALWAYS SHOW YOUR WORK; Keep track of units!

1. When the Sun dies, it will swell into a "red giant", with a diameter around the
size of the orbit of Mars. What will be the surface area of the red giant shell of the Sun then?
_________ km^{2}.

2. Assuming that the Sun's surface temperature goes down by a factor of 2.5 from its
present temperature of 6000 K,
what will that surface temperature be?
_______ K

3. What will the wavelength of the peak of the solar spectrum at that time?
_________ nm. Use Wien's law λ = (0.3 / T) (cm/K).

4. What will the amount of energy radiated per m^{2} of the red giant surface?
_____________W/m^{2} . Use Stephan-Boltzman law J = σ T^{4}

where σ = Stephan-Boltzman constant = 5.67 10^{-8} W/(m^{2} K^{4})

5. What will be the total amount of energy radiated from the Sun then?
______________ W

How does that compare to the Sun's total energy output now? (3.84 x 10^{26} W)

6. (Back to today's Sun): If a Coronal Mass Ejection has an average speed of
1000 km/s on its way to Earth from the Sun, how long will it take to arrive?

Last updated 9/9/2014