PHYSICS 20E Lecture Notes - Lecture 16: Kuiper Belt, Triple-Alpha Process, Terrestrial Planet
Document Summary
We currently live in the golden age of space exploration. Rocky & icy bodies: pluto, eris, ceres, haumea & makemake. All 8 planets orbit in almost the same plane. The sun is a middle-aged, bigger than average star. 99. 8% of the mass of the solar system. The sun shines because it is hot: Emits mostly visible, uv & ir light. Kept hot by nuclear fusion in its core: Can shine for 10 byr by hydrogen fusion. Luminosity = energy given off per time = power. The sun: lsun = 4 x 10^26 joules/sec. The earth gets only 2 billionth of the sun"s energy. The flux of sunlight (power per unit area) decreases with distance from the sun f = flux of sunlight. L = sun"s luminosity d = distance from sun. Energy per unit area is diluted as it streams away from the sun. Earth - 1 au from sun: is warm and has liquid water.
