Anglų skaidrės. The Solar System. Star 9 8 planets 63 (major) moons asteroids, comets, meteoroids. How are planet sizes determined? Measure angular size on sky, Then use geometry. The distances to. Using angular size to get actual size. Masses - determined. Planets orbit the sun counter-clockwise as seen from the North Celestial Pole. Terrestrial Planets. Mercury, Venus, Earth and Mars Close to Sun Small masses. Jovian planets (and earth). Other solar system objects. Asteroids - rocks with sizes greater than 100m across. Most asteroids remain. Known asteroid impact sites. Asteroid sizes range from 100m to about 1000km. They are composed of carbon or iron and other rocky material. Meteoroids – interplanetary rocky material smaller than 100m (down to grain size). Most meteor showers. Meteor crater near Winslow, AZ - the culprit was probably 50 m across weighing. Meteors are rocky. Comets. Dirty snowballs - dust and rock in methane, ammonia and ice. Cometary orbits take. Short period comets. Formation of the Solar System. Any theory to. Our sun and. As the cloud contracts under its own gravity. We’ve seen these disks around other young stars! Beta Pictoris. Conservation of Angular Momentum. Angular momentum mass rotation rate radius. Condensation Theory for Planet Formation. The gas in the flattened nebula would never eventually clump together to form planets. What happened next. A flattened solar. Why the difference between inner and outer planets? Rocky inner planets.