Tuesday, January 17, 2012Tuesday, January 17, 2012

Comets are known as what?Comets are known as what? The comet’s ion tail always extends The comet’s ion tail always extends

where?where? Most asteroids can be found in the ______ Most asteroids can be found in the ______

__________? __________?

TCAP Thursday!! 1/12/12TCAP Thursday!! 1/12/12

In your Table of Contents…In your Table of Contents…

Did you add “Sun Notes” yesterday? If not, Did you add “Sun Notes” yesterday? If not, please add that.please add that.

For today, add “Comets, Meteors, and For today, add “Comets, Meteors, and Asteroids Notes”Asteroids Notes”

Comets, Asteroids, & Comets, Asteroids, & MeteorsMeteors

In addition to planets and moons, the solar system contains many other types of objects, including comets, asteroids, and meteoroids.

CometsComets A A cometcomet is a small body is a small body

of ice, rock, and cosmic of ice, rock, and cosmic dust loosely packed dust loosely packed together.together.

Known as “Known as “dirty dirty snowballssnowballs.”.”

When a comet passes When a comet passes close enough to the sun, close enough to the sun, solar radiationsolar radiation heats the heats the water ice so that the water ice so that the comet gives off comet gives off gas and gas and dustdust in the form of a in the form of a long taillong tail..

The ion tail consists of The ion tail consists of electrically charged electrically charged particles of particles of gasgas..

Comet OrbitsComet Orbits The difference between the orbit of a The difference between the orbit of a

planet and the orbit of a comet is planet and the orbit of a comet is that a comet's orbit is that a comet's orbit is highly highly ellipticalelliptical and a planet's orbit is only and a planet's orbit is only slightly ellipticalslightly elliptical, but more circular., but more circular.

The comet’s ion tail always extends The comet’s ion tail always extends away from the sunaway from the sun. .

This is because the ion tail is blown This is because the ion tail is blown away from the sun by the solar wind. away from the sun by the solar wind.

When the comet Shoemaker-When the comet Shoemaker-Levy 9 broke apart and fell Levy 9 broke apart and fell into Jupiter, some of the into Jupiter, some of the fragments generated fragments generated explosions that produced explosions that produced fireballs larger than Earth.fireballs larger than Earth.

AsteroidsAsteroids AsteroidsAsteroids are small, are small,

rocky bodies in orbit rocky bodies in orbit around the sun.around the sun.

Have Have irregularirregular shapesshapes

Most asteroids orbit Most asteroids orbit the sun in a wide the sun in a wide region between the region between the orbits of Mars and orbits of Mars and Jupiter, called the Jupiter, called the asteroid beltasteroid belt..

Types of AsteroidsTypes of Asteroids Outer region of the Outer region of the

asteroid belt = dark asteroid belt = dark reddish brown to reddish brown to black surfacesblack surfaces

A little closer to the A little closer to the sun = dark gray sun = dark gray surfacessurfaces

Innermost part of Innermost part of the belt = light gray the belt = light gray asteroidsasteroids

Examples: Examples: HektorHektor, , VestaVesta, and , and CeresCeres

MeteoroidsMeteoroids A A meteoroidmeteoroid is a is a

small, rocky body small, rocky body orbiting the sun.orbiting the sun.

Meteoroids are Meteoroids are similar to similar to asteroids, but they asteroids, but they are much are much smallersmaller..

In fact, meteoroids In fact, meteoroids probably come probably come from from asteroidsasteroids. .

MeteoroidsMeteoroids

If a meteoroid enters Earth’s atmosphere and strikes the If a meteoroid enters Earth’s atmosphere and strikes the ground, it is then called a ground, it is then called a meteoritemeteorite..

Stony,Stony, metallic, metallic, and and stony-ironstony-iron are the three major types are the three major types of meteorites. of meteorites.

It travels at such high speeds that it It travels at such high speeds that it heats up and meltsheats up and melts.. As it burns up, the meteoroid glows As it burns up, the meteoroid glows red hotred hot and gives off and gives off

an enormous amount of an enormous amount of lightlight.. From the ground we see a streak of light or From the ground we see a streak of light or shooting shooting

starstar.. The bright streak of light caused by a meteoroid or The bright streak of light caused by a meteoroid or

comet dust burning up in the atmosphere is called a comet dust burning up in the atmosphere is called a meteormeteor. .

Some meteors that hit the ground can cause Some meteors that hit the ground can cause craters.craters.

Meteor CraterMeteor Crater

Planets and moons that have no Planets and moons that have no atmosphere have many more impact atmosphere have many more impact craters than those that do have craters than those that do have atmospheres. atmospheres.

Earth’s atmosphere acts like a shield.Earth’s atmosphere acts like a shield.

In 1954, Mrs. E. Hulitt In 1954, Mrs. E. Hulitt Hodge, of Alabama, was Hodge, of Alabama, was struck by a meteorite as she struck by a meteorite as she was taking her afternoon was taking her afternoon nap. Bruised, but not badly nap. Bruised, but not badly injured, she is one of only injured, she is one of only two people known to have two people known to have been struck by a meteoritebeen struck by a meteorite. .