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.

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

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)

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

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!

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

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

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.