Chapter Questions
The radius of the sun is 0.7 million $\mathrm{km}$. What percentage of the radius is taken up by the chromosphere?
The smallest detail visible with ground-based solar telescopes is about 1 second of arc. How large a region does this represent on the sun? (Hint: Use the small-angle formula.)
What is the angular diameter of a star like the sun located 5 ly from Earth? Is the Hubble Space telescope able to detect detail on the surface of such a star?
How much energy is produced when the sun converts $1 \mathrm{kg}$ of mass into energy?
How much energy is produced when the sun converts 1 kg of hydrogen into helium? (Hint: How does this problem differ from Problem 4?)
A 1-megaton nuclear weapon produces about $4 \times 10^{15} \mathrm{J}$ of energy. How much mass must vanish when a 5-megaton weapon explodes?
Use the luminosity of the sun, the total amount of energy it emits each second, to calculate how much mass it converts to energy each second.
If a sunspot has a temperature of $4240 \mathrm{K}$ and the solar surface has a temperature of $5800 \mathrm{K}$, how many times brighter is the surface compared to the sunspot? (Hint: Use the Stefan-Boltzmann law, Chapter $7 .)$
A solar flare can release $10^{25}$ J. How many megatons of TNT would be equivalent? (Hint: A 1-megaton bomb produces about 4 $\times 10^{15}$ ].)
The United States consumes about $2.5 \times 10^{19} \mathrm{J}$ of energy in all forms in a year. How many years could you run the United States on the energy released by the solar flare in Problem 9 ?
Neglecting energy absorbed or reflected by Earth's atmosphere, the solar energy hitting 1 square meter of Earth's surface is $1360 \mathrm{J} / \mathrm{s}$ (the solar constant). How long does it take a baseball diamond (90 ft on a side) to receive 1 megaton of solar energy?