Solar

Solar-System Debris

Objectives:

Key Terms:

Notes: (27-4)

Other than suns, planets, and moons, our solar system consists of various types of rocks and debris. The impact of these debris on the planets and moons give them the distinct features that have been recorded.

Comets

Comets are often called dirty snowballs - made of dirt nuclei and frozen gasses and water

Most exist outside Neptune in a region called the Edgeworth-Kuiper belt

Also referred to as TNOs - Trans Neptune Objects

few have elliptical orbits that move them close to the sun

	forms a coma - large cloud of dust and gas expanding out to space
	the coma always points away from the sun - precedes the retreating comet
	Halley's comet returns every 75 years

Halley's Comet (www.project2061.org/images/ home/comet.jpg)

How a meteoroid stream is created. (www.uwo.ca/wnews/centre/ comets.jpg)

Asteroids

irregular fragments of rock

most are less than 1 km long

most revolve around the sun in the same direction as the planets in the asteroid belt between Mars and Jupiter

few have elliptical orbits and have collided with planets in the past

65 million years ago with Earth - extinction of the dinosaurs

(bruckner.homelinux.net/ images/solsys.jpg)

Meteoroids and Meteors

a meteoroid is a fragment of rock or ice that is traveling in space

	can be grain sized to 100 m across
	smaller than an asteroid

once the meteoroid comes in contact with Earth's atmosphere it becomes a meteor

sometimes a shooting star

meteor showers are when large numbers of meteoroids enter our atmosphere at the same time

often occurs as Earth passes through the tail of a comet

Meteorite is the part of the meteor that reaches the Earth

three types

Stony

	94%
	look like dark igneous rocks
	made primarily of silicates

Iron

	5%
	made primarily of iron and nickel

Stony-Iron

	1%
	formed when the molten iron and stony meteors come in contact with each other

Impact Crater

bowl-shaped depression that remains after a meteorite strikes the Earth

~150 known on Earth's surface

Arizona's Barringer Meteor Crater

	49,000 yrs ago
	iron meteorite ~ 45 meters in diameter
	left a crater 1200 meters in diameter

Barringer Meteor Crater (cfa-www.harvard.edu/cfa/ ep/meteor/barringer.jpg)

Last modified: May 16, 2003