AST101H5 Lecture Notes - Lecture 8: Giant Planet, Weight Pulling, Rotational Speed
Document Summary
Low densities require the lightest elements (hydrogen, helium) o. Conclusion: jovian planets are 99% (by count) hydrogen and. This is very similar to the sun"s composition helium. Sunlight reflects from the jovian planets and come to earth o. The absorption wavelengths contain the pattern of many hydrogen molecules (hydrogen gas, water, ammonia, methane) We don"t see helium"s absorption pattern because helium needs high heat but these planets are cold. The jovian planets are very cold because they are all far from the sun o o. Intensity of sunlight 1 (distance)2= % of earth"s heating. At low temperatures, the molecules and atoms move very slowly. Because of the low speed, not even the lightest elements (with the fastest speeds) can escape. Jovian planets hold onto hydrogen and helium, as well as all others. Hydrogen + helium= 99% of all matter in space large masses, diameters and gravities but low densities.
