Composition of Objects in Space Notes 4.4

1. Composition of Objects in SpaceNotes 4.4 • Composition = the types of materials and how they are arranged in an object • Objects to be looked at: terrestrial planets, gaseous outer planets, Oort Cloud, Kuiper (ky-per) Belt, asteroids, meteors, and comets.

2. Terrestrial Planets • Rocky, with metal cores and solid surfaces. • “Close” to the sun compared to gaseous planets** • **Not as close to the sun as other terrestrial planets are to their star in other solar systems

3. Gaseous Outer Planets • Jupiter, Saturn, Uranus, Neptune • Have no solid surfaces  Hydrogen and Helium • We can not yet image gas planets around other stars (in other solar systems)

4. Oort Cloud • This is only a working hypothesis (by Jan Oort, 1950) • Says that there is a vast cloud at the outer reaches of our solar system • 50,000 AU away • Is where long-period comets come from

5. Kuiper Belt • Past Neptune • A disk-shaped area with many icy bodies that may sometimes cross Neptune’s orbit • This either flings them out of the solar system or in towards inner planets!

6. Asteroids • Rock and metal objects • They do not “stick” together to form a planet because of Jupiter’s gravity • That causes them to bounce off and break each other apart • Located between Mars and Jupiter

7. Meteors • = “Shooting Star” • When dust and icy chunks enter earth’s atmosphere, heat up, glow, and then burn down • Becomes a meteorite when it makes it to the surface of the Earth

8. Comets • Are further from the sun than asteroids. • Are balls of dust and ice • When their orbit passes close enough to the sun, that makes the vapor trail we see.