Weekly Challenge

nuclear fusion

How does nuclear fusion occur in the sun?  The core’s extreme temp and density are just right for the nuclear fusion of hydrogen to helium through the proton-proton chain.  Gravitational equilibrium acts as a thermostat to regulate the core temp b/c the fusion rate is very sensitive to temp.

How does energy from fusion get out of the sun?  Randomly bouncing photons carry it through the radiation zone.  The rising of hot plasma carries energy through the convection zone to the photosphere.

How do we know what is happening inside the sun?  Mathematical models agree w/ observations of solar vibrations and solar neutrinos.

How does solar activity affect humans?  Bursts of charged particles from the sun can disrupt communications, satellites, and electrical power generation.

How does solar activity vary w/ time?  Activity rises and falls in 11-year cycles

How would the apparent brightness of Alpha Centuari change if it were 3x farther away?  1/9 as bright.  Use apparent luminosity equation (3^2 = 9).