ASTR 151 Lecture 19: ASTR 151-Lecture 19
Document Summary
Stars= 1 (the sun) 99. 8% of the solar system"s mass. Planets= 8: mercury, venus, earth, mars, jupiter, saturn, uranus, neptune. Dwarf planets= 5: ceres, pluto, haumea, makemake, eris. There are 3,394 extrasolar planets confirmed: sometimes exoplanet. Most are larger than jupiter and orbit their host stars closer than mercury orbits the sun. Habitable zone earth- like exoplanets: kepler 186f, kepler 62f, proxima centauri b. Semimajor axis- distance from the sun: known from kepler"s 3rd law once orbital period known. Orbital period (p)- time to make a single revolution around the sun: known through careful observations of planetary positions and orbital mechanics. Radius-center-to-surface distance: known through angular diameter measurements coupled with knowing the distance to the planet. Mass- number of kilograms of matter: known through newton"s law of gravity. Rotational period- length of day: through observations of surface features, clouds, storms.
