http://www.youtube.com/watch?v=BYcTN8H7ysw

Good Planets are hard to find

Classifying Objects in the Solar System

Link to directions:http://www.astrosociety.org/education/publications/tnl/70/pluto.html#10Link to images:http://www.astrosociety.org/education/publications/tnl/70/solarsystemcards.pdf

ACTIVITY 1: SORTING

THE SOLAR SYSTEM

SURVEYDo you think Pluto should be a planet?

YES NO

Image: Hubble Space Telescope

Read this article

Hubble Observations of Ceres and Pluto• http://www.astrosociety.org/education/public

ations/tnl/70/pluto.html

There is a handout that goes with this article titled: Hubble Observations of Ceres and Pluto. You can find it in the folder titled Classifying Objects in the Solar System

The Original Definition of a Planet

Planet is derived from the

Greek word αστήρ πλανήτης(Wandering Star)

This was anything that wandered in the sky differently that the

fixed stars

How many planets are there?Geocentric Model (Early Greek)

Total Number of Planets = 7

Heliocentric Model (1550)Total number of Planets = 6

Due to Reclassification of Earth, Moon and Sun

This was all that could be seen by the unaided eye.

Then Uranus was discovered (1781)Total Number of Planets = 7

Total number

of planets = 11

Then Astraea was discovered (1845)

Number of planets = 12

At this point the definition for planet is

still “Wandering Star”.

Moon diameter compared to the first 10 asteroids

to be discovered

Next came Neptune (1846)

Total number of planets = 13

Reclassification of 1851

• 1851 – 15 asteroids • A minor planet is an astronomical object in direct orbit

around the Sun that is neither a dominant planet nor originally classified as a comet.

• Minor planets can be dwarf planets, asteroids, trojans, centaurs, Kuiper belt objects, and other trans-Neptunian objects.[1]

• The first minor planet discovered was Ceres in 1801 (although from the time of its discovery until 1851 it was considered to be a true planet).

• The orbits of more than 570,000 objects have been archived at the Minor Planet Center.[2]

http://news.discovery.com/space/zooms/uranus-knocked-on-side-111007.html

How are the planets spaced out?

Use your Pocket Solar System to roughly describe how

the planets in our solar system are spaced out?

Does the spacing seem to follow a pattern?

Just worth a note: Titus-Bode Law

What is a Planet???

Video (4:45 minutes)http://www.universetoday.com/13573/why-pluto-is-no-longer-a-planet/

Why Pluto is No Longer a Planet?

International Astronomical Union (IAU)

• Planets

• Dwarf Planets

• Small Solar System Bodies

RESOLUTION B5

Ceres and Pluto: Dwarf Planets as a New Way of Thinking

about an Old Solar SystemActivity Link:

DefinitionA planet is a celestial body that

1. Is in orbit around the Sun (or other star if speaking about exoplanets)

2. Has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium

shape (round)3. Has cleared the

neighborhood around its orbit.

4. Is NOT a satellite

Examples

Planets ~ There are 8

DefinitionA dwarf planet is a celestial body that1. Is in orbit around the Sun2. Has sufficient mass for its self-

gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium shape

3. Has NOT cleared the neighborhood around its orbit

4. Is NOT a satellite

Examples: Ceres, Pluto, Eris

Dwarf Planets

Click the image to go to Mike Brown’s Dwarf planet page

Notable Dwarfs

Eris by Hubble Eris Orbit

Eris Orbit Eccentricity and Inclination

Eris Discovery (3 frames over 3 hours)

Notable Dwarfs

Haumea Sedna

DefinitionAn asteroid is a celestial body that:

1. Orbits the Sun inside the orbit of Jupiter

2. DOES NOT have sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium shape (IT IS NOT ROUND)

3. HAS NOT cleared the neighborhood around its orbit

4. IS NOT a satellite

Examples

Asteroids

Comparison of Astroids

Mars and asteroids: size comparisons

Click on the image to visit the NEAR mission webpage

Ceres Vesta

Dwarf Planet or Asteroid?

Click on the image to visit the DAWN mission website

TNO’s are

any objects in the Solar System that orbits the Sun at

a greater average distance than Neptune.

Trans-Neptunian Objects (TNO’s)

A Plutoid (or ice dwarf) is 1. trans-Neptunian object 2. dwarf planet: that is, a

body orbiting beyond Neptune that is large enough to be rounded in shape.

Plutoids

Comets

Stardust

Click on the Image to link to the Deep Impact mission page

Definition • All other objects, except

satellites, orbiting the Sun

Examples• Most asteroids• Most Trans-Neptunian

Objects (TNO’s)• Comets• Other small bodies

Small Solar System Bodies

Pluto’s changing landscape• http

://hubblesite.org/newscenter/archive/releases/2010/06/video/a/

Pluto is:1. Dwarf Planet2. Kuiper Belt Object3. Trans-Neptunian Object4. Plutoid

Link here to PlutoToday.com http://www.plutotoday.com/

So What is Pluto?

Pluto’s fifth moon!

Click on the image to view a short video of the motion of the moons.

Click on the image to visit the NEW HORIZONS mission webpage

Originally You thought a Planet must have…

Atmospheres

Magnetic Fields

Moons

CoreLocation

OrbitsSize or Shape

GRAVITY

SURFACELAYERS WATER

Use the Internet to Research

Earth Ceres Vesta Pluto

1. www.nineplanets.org2. http://ssd.jpl.nasa.gov/

One Comparison

Earth has a relatively high density compared to the other three objects

The Earth is a planet and the other three are not, maybe density should be considered when classifying

planets/non planets.Question:

How does density affect the other characteristics of a planet?

Earth Ceres Vesta PlutoDensity (g/ 5.5 2.0 2.4 2.0

𝑫𝒆𝒏𝒔𝒊𝒕𝒚=𝑴𝒂𝒔𝒔

𝑽𝒐𝒍𝒖𝒎𝒆

Should Pluto be a Planet???

Conclusions

The International Astronomical Union has chosen one characteristic (the extent to which a body has

cleared its orbital neighborhood of other bodies) as the distinguishing characteristic of a planet versus a

dwarf planet, there are many other characteristics to consider.

Conclusions

Many planetary scientists would rather see a definition that focused more on characteristics of the body itself rather than where it is or what is near it.

The more that we learn about our solar system, the more our classification schemes are challenged to include

new discoveries.

New Horizons

IBEXNEAR

Neil Degrasse Tyson on Pluto

New York Public Radio (5:10 minutes)http://www.youtube.com/watch?v=4Rwe54vtvUA

PBS Movie (The Pluto Files 52:52 minutes)http://www.pbs.org/wgbh/nova/space/pluto-files.html

Allen Stern’s thoughts on Pluto (Planetary Scientist)

Nova Podcast (6:30 minutes)• http://

www.pbs.org/wgbh/nova/space/defense-pluto.html

Conclusion for Pluto – NOT A PLANET, NOT EVEN THE LARGEST OF THE DWARF PLANETS, BUT SITS A CLOSE SECOND!

Mike Brown – CalTech Astrophysicist

http://www.youtube.com/watch?v=C9pXpXAl8m8&feature=related

Facts and QuizzesInteresting Facts about our Dwarf Planetshttp://www.youtube.com/watch?feature=endscreen&v=Ho5FEyftFss&NR=1

Quiz on Plutohttp://www.space.com/16537-pluto-quiz-dwarf-planet-moons.html

Dwarf Planet Quiz1. http://www.astronomyquiz.info/dwarf-planets-quiz.html2. http://www.funtrivia.com/playquiz/quiz3249712533f30.html

QUIZ IMAGE 1

INFORMATION

a ) P l a n e t b ) D wa r f P l a n e t c ) S m a l l S o l a r Sy s te m B o d y

This object has not cleared out its neighborhood orbit.

Image 2

INFORMATION

This object is in an orbit around the Sun between the orbits of Mars and Jupiter.

Image 3

INFORMATIONThis object is in an orbit

around the Sun between the orbits of Mars and Jupiter.

Image 4

INFORMATION

This object orbits the Sun past Neptune’s average distance

from the Sun

Image 5

NFORMATION

This object contains more than 90% of the total mass in its

path around the sun

Image 6

INFORMATION

This object is in an orbit around the Sun between the orbits of Mars and Jupiter.

Image 7

INFORMATION

This object would be rounded but its extreme rotation causes

it to bulge.

Image 8

INFORMATION

This object’s orbit is highly eccentric.

Image 9

INFORMATION

This object orbits the Sun at an average distance of .3 AU

Image 10

INFORMATION

This object is the most distant of 8 objects in its classification.