Small Bodies in the Solar SystemSmall Bodies in the Solar System

ESS (2015-16)ESS (2015-16)

Small Planetary BodiesSmall Planetary Bodies

In addition to planets & moons, the solar system contains many other types of objects:

including comets, asteroids, and meteoroids.

In addition to planets & moons, the solar system contains many other types of objects:

including comets, asteroids, and meteoroids.

Comets vs. Asteroids vs. MeteorsComets vs. Asteroids vs. Meteors

Comet StructureComet Structure

Nucleusgas and dust are released and form an

atmosphere around the comet called the coma

Dust Tail Usually white

Ion Tail (ionized gas)Usually blue

Nucleusgas and dust are released and form an

atmosphere around the comet called the coma

Dust Tail Usually white

Ion Tail (ionized gas)Usually blue

Comet’s TailComet’s Tail

A comet's tail points away from the Sun due to solar wind

Tail gets longer when it is close to the Sun.

Heat from the Sun melts, actually sublimates the ices from comet is mostly made of.

A comet's tail points away from the Sun due to solar wind

Tail gets longer when it is close to the Sun.

Heat from the Sun melts, actually sublimates the ices from comet is mostly made of.

Comet’s OrbitComet’s Orbit

Two factors describe orbit Size of orbit

Long-period > 200 years

From Kuiper Belt or Oort Cloud Short-period < 200 years

EccentricityHow “oval shaped”

0 = circle, 1 = very long ovalHalley’s Comet has a high eccentricity

Comet moves faster as orbits sun

Two factors describe orbit Size of orbit

Long-period > 200 years

From Kuiper Belt or Oort Cloud Short-period < 200 years

EccentricityHow “oval shaped”

0 = circle, 1 = very long ovalHalley’s Comet has a high eccentricity

Comet moves faster as orbits sun

Halley’s Comet 76 yrs

Comet Kahoutek 75,000yrs

Comet’s OrbitComet’s Orbit

Closest to sun – Perihelion

Furthest from sun - Apihelion

Closest to sun – Perihelion

Furthest from sun - Apihelion

Rosetta MissionRosetta Mission

Comet SimulationComet Simulation

Oort CloudOort Cloud

Where do they come from?Where do they come from?

Oort CloudOort Cloud

Not actually seen

Theoretical explanation

Billions to 2 trillion of objects

Water, ammonia, methane

2000 AU (2000 x distance from sun to Earth)

~ 1 light year thick

Not actually seen

Theoretical explanation

Billions to 2 trillion of objects

Water, ammonia, methane

2000 AU (2000 x distance from sun to Earth)

~ 1 light year thick

Asteroid BeltAsteroid Belt

AsteroidsAsteroids

Size

Meters – 900 km (too small to be planet)

Shape

Irregular

Larger one are more spherical

Content

Lighter – more rockDarker – more metal

Size

Meters – 900 km (too small to be planet)

Shape

Irregular

Larger one are more spherical

Content

Lighter – more rockDarker – more metal

AsteroidsAsteroids

Sometimes considered planetoids or minor planets

Most located in asteroid belt (between Mars & Jupiter)

> 200 asteroids larger than 60 miles (100 kilometers) in diameter.

> 750,000 asteroids larger than three-fifths of a mile (1 km) in diameter and

millions of smaller ones.

Sometimes considered planetoids or minor planets

Most located in asteroid belt (between Mars & Jupiter)

> 200 asteroids larger than 60 miles (100 kilometers) in diameter.

> 750,000 asteroids larger than three-fifths of a mile (1 km) in diameter and

millions of smaller ones.

AsteroidsAsteroids

Ceres – largest asteroid in asteroid belt

580 miles across

Considered dwarf planet

Ida – has a natural satellite, 56 km long

Dactyl

1.5 km Dactyl.

Ceres – largest asteroid in asteroid belt

580 miles across

Considered dwarf planet

Ida – has a natural satellite, 56 km long

Dactyl

1.5 km Dactyl.

AsteroidsAsteroids

A large asteroid may have hit the Earth when the dinosaurs were alive – ~65 million years ago.

A large asteroid may have hit the Earth when the dinosaurs were alive – ~65 million years ago.

AsteroidsAsteroids

Eventually many will drop out of orbit

maybe from a collision with another asteroid and heads toward Earth.

< 10 km across, will burn up in the atmosphere.

> 10 km across, will hit the surface of the planet.

Hundreds of millions of years ago, collisions with asteroids more often.

Over time, the # of asteroids in the path of the Earth decreased and collisions become less frequent.

Eventually many will drop out of orbit

maybe from a collision with another asteroid and heads toward Earth.

< 10 km across, will burn up in the atmosphere.

> 10 km across, will hit the surface of the planet.

Hundreds of millions of years ago, collisions with asteroids more often.

Over time, the # of asteroids in the path of the Earth decreased and collisions become less frequent.

Meteoroids…Meteoroids…

Meteoroid - A small particle from an asteroid or comet orbiting the Sun. 

Meteor - A meteoroid that is observed as it burns up in the Earth's atmosphere – a shooting star.

Meteorite - A meteoroid that survives its passage through the Earth's atmosphere and impacts the Earth's surface

Meteoroid - A small particle from an asteroid or comet orbiting the Sun. 

Meteor - A meteoroid that is observed as it burns up in the Earth's atmosphere – a shooting star.

Meteorite - A meteoroid that survives its passage through the Earth's atmosphere and impacts the Earth's surface

Meteoroids…Meteoroids…

Size

Pebble to boulder (smaller than asteroids)

Shape

Irregular

Content

From asteroids & comets, so likely metal & rock

Size

Pebble to boulder (smaller than asteroids)

Shape

Irregular

Content

From asteroids & comets, so likely metal & rock

MeteorMeteor

Heats up to > 2,000˚C. Creates a streak of light called a “shooting

star”. Fireballs - larger meteors -> brighter flash On average, 1/ 10 minutes, or about 6/hour

Heats up to > 2,000˚C. Creates a streak of light called a “shooting

star”. Fireballs - larger meteors -> brighter flash On average, 1/ 10 minutes, or about 6/hour

Meteor ShowersMeteor Showers

Usual rate = 6/hour

Meteor Shower = rate may be as high as 60/hour

Occur when Earth passes through the tail or debris of a comet

Perseids (mid-August)

Leonids (mid-November)

Usual rate = 6/hour

Meteor Shower = rate may be as high as 60/hour

Occur when Earth passes through the tail or debris of a comet

Perseids (mid-August)

Leonids (mid-November)

Draconid Meteor ShowerDraconid Meteor Shower

MeteoriteMeteorite

Meteorites could be fragments from collisions involving asteroids.

Most meteorites weigh only a few pounds and cause little damage.

Impact craters Earth – not many, thick atmosphere

Moon & Mercury – lots, no atmosphere

Where to find – Antarctica

White & not much snowfall, doesn’t melt

Meteorites could be fragments from collisions involving asteroids.

Most meteorites weigh only a few pounds and cause little damage.

Impact craters Earth – not many, thick atmosphere

Moon & Mercury – lots, no atmosphere

Where to find – Antarctica

White & not much snowfall, doesn’t melt

MeteoritesMeteorites

Flagstaff, Arizona49,000 years agoSize

Meteorite about 150 feet in diameter Weighed 650 pounds

Energy = 2.5 million tons of dynamiteCrater

4000 ft wide, 650 ft deep

Flagstaff, Arizona49,000 years agoSize

Meteorite about 150 feet in diameter Weighed 650 pounds

Energy = 2.5 million tons of dynamiteCrater

4000 ft wide, 650 ft deep

Barringer Meteorite Crater

Speed (? From yesterday)Speed (? From yesterday)

Comets

~ 40 km/s

Asteroids~ 25 km/s,

Meteors11 – 72 km/s

Comets

~ 40 km/s

Asteroids~ 25 km/s,

Meteors11 – 72 km/s

Our Solar SystemOur Solar System

Scale Model of Solar System (p. 9)Read directions

Calculate distances

Color planets

Obtain string/ribbon

Cut out & place planets on string at appropriate distance 1 at a time, (so you don’t lose them!)

clear tape probably best for this.

Scale Model of Solar System (p. 9)Read directions

Calculate distances

Color planets

Obtain string/ribbon

Cut out & place planets on string at appropriate distance 1 at a time, (so you don’t lose them!)

clear tape probably best for this.