Presentation on theme: "Minor Members of the Solar System"— Presentation transcript:
1Minor Members of the Solar System Chapter 23, Section 4
2AsteroidsAsteroid – small rocky bodies that have been likened to “flying mountains”Most asteroids lie between the orbits of Mars and Jupiter. They have orbital periods of 3 to 6 years.Some have very eccentric orbits, a few regularly pass Earth and our moonMany asteroids have irregular shapes, and some planetary geologists believe the asteroids are fragments of a broken planet (pulled apart by the immense gravity of Jupiter)
4CometsComets – pieces of rocky and metallic materials held together by frozen gasesMost comets travel in elongated orbits, taking them past Pluto and take hundreds of thousands of years to go around the sun.Coma – glowing head of a comet, caused by the solar energy vaporizing frozen gasesA small glowing nucleus with a diameter of only a few kilometers can sometimes be detected within a coma. As comets approach the sun, some develop a tail that extends for millions of kilometers.The tail of the comet always points away from the sun, this is accounted for by the solar wind and radiation pressure
7Beyond the PlanetsKuiper Belt – where most short-period comets are thought to originate from, it is a belt of material orbiting outside the orbit of Neptune.Oort Cloud – Unlike the Kuiper Belt comets, these comets have longer orbital periods and aren’t confined to the plane of the solar system. The Oort Cloud appears as a spherical shell of comets and other materials surrounding our solar system.
9MeteoroidsMeteoroid – a small solid particle that travels through spaceMost meteoroids originate from any one of the following sources: (1) interplanetary debris that was not gravitationally swept up during the formation of the solar system, (2) material from the asteroid belt, or (3) the solid remains of comets that once traveled near Earth’s orbitMeteor – meteoroids that enter Earth’s atmosphere and burn up, a “shooting star”The light that we see is caused by the friction between the meteor and the airMeteorite – a meteoroid that reaches Earth’s surfaceA few meteorites have blasted out craters on Earth’s surface
13The Age of the Solar System How did scientists determine the age of the Solar System?They use radiometric dating to determine that the oldest meteorites found on Earth formed more than 4.54 billion years agoScientists believe that the composition of these meteorites is similar to the composition of other materials in the inner solar system during its formationThe oldest moon rocks are believed to be ~4.5 billion years oldThe oldest known Earth rocks are found in Canada ~4 billion years old