Download - Dwarf planets
Dwarf Planets
Solar System Debris
Planets vs Dwarf PlanetsPlanets
– Orbits the Sun directly– Massive enough to be
rounded by its own gravity– Has cleared the smaller
bodies from its orbit
Dwarf Planets– Orbits the Sun directly– Massive enough to be
rounded by its own gravity– Has not cleared the smaller
bodies from its orbit
Official Dwarf Planets
1. Ceres – discovered on January 1, 1801 (45 years before Neptune),
2. Pluto – discovered on February 18, 1930,.
3. Eris – discovered on January 5, 2005.
4. Haumea – discovered on December 28, 2004. Makemake – discovered on March 31, 2005.
5.
The Dwarf Planets in Comparison
Name
Diameter relative to
Luna
Mass relative to
LunaDensity (Kg/m3)
Temperature (K)
Orbital period (yrs)
Ceres 28% 1.3% 2080 167 4.6
Pluto 69% 17.8% 2000 44 248
Haumea 33% 5.7% 2600-3300 32 285
Makemake 43% ~5%? ~2000? ~30 309
Eris 78% 22.7% 2300 42 557
Ceres• Found in the asteroid belt in 1801
• Considered a planet for half a century before reclassification as an asteroid.
• Once considered the largest asteroid
• Classified as a dwarf planet on September 13, 2006.
Ceres - The numbers– Contains 1/3 the total mass of all the asteroids– Orbital Period: 4.6 years– Semi-major axis: 2.8 AU– Diameter: 950 Km– Temperature: 167 K
Ceres – Discovery• Possibility of its existence first suggested in
1772• Discovered in 1801 by Giuseppe Piazzi• Named for the Roman goddess
of plants
Ceres - Characteristics • Surface like a C-class asteroid• Possibly differentiated interior?• Bright spot of unknown composition• Possible tenuous atmosphere and frost
The Dawn Mission
• Will study asteroids Vesta and Ceres
• Will arrive at Vesta in July 2011
• Will arrive at Ceres in February 2015
Kuiper Belt Objects (KBO)• AKA: Trans-Neptunian Objects (TNO)• Comet-like material• Disk beyond Neptune
Pluto• Considered the 9th planet from 1930 to 2006
• Classified as a planet for 76 years.
• Named for Roman god of the underworld
• Reclassified as a dwarf planet on August 24, 2006
• Became the first dwarf planet
Pluto - Discovery• Observations of Neptune
showed that something was perturbing its orbit
• In 1906 the Lowell Observatory began a search for “Planet X”
• Clyde Tombaugh discovered Pluto in 1930 using a blink comparator
Pluto - Discovery
Pluto in the blink comparator
Pluto - The numbers– Orbital Period: 248 years– Semi-major axis: 39 AU– Diameter: 2300 Km– Temperature: 44 K– 3 known moons• Charon : more than ½ the size of Pluto• Nix• Hydra
Pluto – The Orbit
• Highly eccentric– Inside Neptune from 79-99
• Tilted 17º from ecliptic
Pluto – What is it really?
• Highly eccentric orbit• +Atmosphere thaws and freezes depending on
distance from Sun• +Highly inclined from ecliptic• = comet
Haumea
• A plutoid– Dwarf planets beyond
Neptune
• Named after the goddess of the island of Hawaii
• Has two known moons
Haumea - Discovery
• Discovered in 2004 by Mike Brown at CalTech
• Discovery first announced by a Spanish team …BUT!
• They stole the data• Accepted as a dwarf planet
on September 17, 2008.
Haumea’s Shape• Spins very fast– A rotation in 4 hours
• This rotation causes it to deform
• Formed into football shape
Haumea – the numbers
– Orbital Period: 285 years– Diameter: ~1400Km– Semi-major axis: 43.1 AU– Temperature: <50 K
Makemake
• Plutoid• Named for the
creator god of Easter Island
• No known satellites– Unique among large
KBOs
Makemake - Discovery
• Discovered in 2005 by Mike Brown at CalTech
• Further from ecliptic than other dwarfs
• Accepted as a dwarf planet on July 11, 2008.
Makemake – the nubmers
– Orbital Period: 309 years
– Semi-major axis: 43.1 AU
– Inclination: 29º– Diameter: 1500Km– Temperature: 30-35 K
Eris• Largest dwarf planet in
solar system• 27% more massive than
Pluto• Named for Greek goddess
of discord
Eris - Discovery
• Discovered in 2005 by Mike Brown at CalTech
• Called the "tenth planet” in media reports
• Originally named Xena
• Accepted as a dwarf planet on September 13, 2006.
Eris? Really?
Me again.
Eris – The numbers
– Orbital Period: 557 years– Semi-major axis: 68 AU– Diameter: 2400? Km– Temperature: 42.5 K– 1 known moon• Dysnomia
Other Trans-Neptunian Objects
Pluto’s Demise