Asteroids, Meteroids, and Asteroids, Meteroids, and Comets…Oh my!Comets…Oh my!

AsteroidsAsteroids

AsteroidsAsteroids – A rocky lump of frozen gas – A rocky lump of frozen gas that can range in size from a few hundred that can range in size from a few hundred feet to several hundred miles wide.feet to several hundred miles wide.

Matter that is similar in composition to the Matter that is similar in composition to the planets. Sometimes, it’s called a planets. Sometimes, it’s called a PlanetoidPlanetoid..

Orbit in a belt between Mars and Jupiter.Orbit in a belt between Mars and Jupiter. Largest asteroid known: Largest asteroid known: Ceres Ceres (1801)(1801)

Asteroid Gaspra – photographed by Asteroid Gaspra – photographed by the the GalileoGalileo spacecraft in 1991. spacecraft in 1991.

What prevents the Asteroids in the What prevents the Asteroids in the belt from plunging into the sun and belt from plunging into the sun and

hitting the inner planets in the hitting the inner planets in the process?process?

The Sun’s gravity and Jupiter’s The Sun’s gravity and Jupiter’s gravity!gravity!

MeteoroidsMeteoroids

MeteoroidsMeteoroids – Small fragments of – Small fragments of matter, like rock, stone, and metals matter, like rock, stone, and metals (smaller than asteroids) that orbit the (smaller than asteroids) that orbit the sun at a variety of speeds; pieces of sun at a variety of speeds; pieces of planets, moon, or asteroidsplanets, moon, or asteroids

Meteor Meteor - - “shooting star”“shooting star”• This happens when a meteoroid enters This happens when a meteoroid enters

Earth’s atmosphere and begins to burn.Earth’s atmosphere and begins to burn.• Briefly visibleBriefly visible• FireballFireball – Long streaks of bright light – Long streaks of bright light

created by these racing meteorscreated by these racing meteors

Fireball from a meteor in the night Fireball from a meteor in the night sky.sky.

Pennsylvania 1992Pennsylvania 1992

Sometimes meteors strike Earth!Sometimes meteors strike Earth!

MeteoriteMeteorite – a meteor that impacts the – a meteor that impacts the ground.ground.• Most meteorites fall into the oceans.Most meteorites fall into the oceans.• Most meteorites fall to earth as dust, because Most meteorites fall to earth as dust, because

they burn up in the atmosphere.they burn up in the atmosphere.• ““Micrometeorites” strike Earth daily. These Micrometeorites” strike Earth daily. These

can be as small as pebbles. can be as small as pebbles. • Size of a mountain every 10,000 years.Size of a mountain every 10,000 years.• CratersCraters are created when large meteorites are created when large meteorites

strike a moon or planet.strike a moon or planet. 3 km wide in Quebec, Canada3 km wide in Quebec, Canada

Largest Meteorite to strike US – Oregon Largest Meteorite to strike US – Oregon 19021902

1954 – crashed through the living room 1954 – crashed through the living room and injured a woman.and injured a woman.

What’s the difference between a What’s the difference between a meteoroid, meteor, and meteorite?meteoroid, meteor, and meteorite?

Meteoroid – still in spaceMeteoroid – still in space Meteor – enters earth’s Meteor – enters earth’s

atmosphere atmosphere Meteorite – meteor that Meteorite – meteor that

strikes earth because it’s strikes earth because it’s so big it doesn’t burn up.so big it doesn’t burn up.

Seen during a football Seen during a football game.game.

Pieces of it crashed into Pieces of it crashed into the trunk of a parked car.the trunk of a parked car.

Meteor ShowerMeteor Shower

The 1966 Leonids Meteor ShowerThe 1966 Leonids Meteor Shower Arizona; 2300/minute for 20 minutesArizona; 2300/minute for 20 minutes

CometsComets

CometsComets – lumps of frozen gas and rock that orbit – lumps of frozen gas and rock that orbit the sun in a highly eccentric way.the sun in a highly eccentric way.

A heavenly body that is usually named after its A heavenly body that is usually named after its discoverer.discoverer.

Believed to originate in an Oort cloud. (Huge cloud Believed to originate in an Oort cloud. (Huge cloud that is thought to surround our solar system).that is thought to surround our solar system).

NucleusNucleus – the center of a comet. – the center of a comet. ComaComa – large halo of gas and dust that forms around – large halo of gas and dust that forms around

the nucleus of a comet when it gets close to the sun. the nucleus of a comet when it gets close to the sun. It actually loses mass as it gets close to the sun. It actually loses mass as it gets close to the sun.

More about a comet More about a comet

Comets orbit the sun in an Comets orbit the sun in an elliptical elliptical pattern.pattern.

Comets have tailsComets have tails. Their tails are made . Their tails are made of frozen gases, cosmic dust, and rocky of frozen gases, cosmic dust, and rocky particles. As a comet travels toward the particles. As a comet travels toward the sun, its head leads the way. But as it sun, its head leads the way. But as it travels away, its tail leads the way. This is travels away, its tail leads the way. This is due to due to Solar winds.Solar winds.

Haley’s cometHaley’s comet – a space curiosity that – a space curiosity that returns to Earth’s view every 76 years.returns to Earth’s view every 76 years.

Haley’s CometHaley’s Comet It has been spotted for thousands of years.It has been spotted for thousands of years.

Sir Edmond Halley – English Sir Edmond Halley – English astronomer (1656-1742) astronomer (1656-1742)

Can you find Haley’s Comet in the Can you find Haley’s Comet in the tapestry below dated from 1066 A.D.?tapestry below dated from 1066 A.D.?