solar systems chapter 21. definition objects that revolve around a star major members – planets...
TRANSCRIPT
SOLAR SYSTEMSCHAPTER 21
definition
• Objects that revolve around a star• Major members
– Planets– Moons
• Minor members– Dwarf planets– Asteroids– Comets– meteoroids
What is a planet?(as of Aug. 2006)
• The IAU said that the definition for a planet is now officially known as "a celestial body that
• (a) is in orbit around a star
• (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a (nearly round) shape and
• (c) has cleared the neighborhood around its orbit."has cleared the neighborhood around its orbit." (not in a swarm of rocks) (not in a swarm of rocks)
Our solar system scoreboard
• Planets= 8• Moons= 167• Dwarf planets= 5• Asteroids= 536,000+• Comets= 3,062
Exosolarsystems
• Other solar systems• 661 new solar systems confirmed!• Over 3000 planets (exoplanets)
First discovered in 1995
Estimated over 50 BILLION
Earth like planets(habitable zone)
• Maybe 2?• Gliese D
– 6x more massive than earth “superearth”– In Libra– 20 lya
• HD 85512 b– In Vela– 26 lya
HOW DO ASTRONOMERS FIND NEW PLANETS???????
Radial Velocity
• Planets are detected by studying light shifts due to star wobbles
• Uses Doppler Effect– Red light moves AWAY– Blue light moves
TOWARDS
Astrometry
• Measures star wobbles from geometry
Transit method
• Planet blocks star (eclipse)• Light from star is lessen• Kepler mission
Optical detection
• Block star’s light out using a chronograph
Exoplanet missions
• Kepler- launched 2009• Has found 77 planets so far
METHODS to find a new planet
• http://planetquest.jpl.nasa.gov/Planet_Finder/planetfinder.html
Other research
• LBT (large binocular telescope)• Keck telescopes (Hawaii)• Spitzer Space Telescope
– Infrared telescope
Our solar systemOur solar system
The planets drawn The planets drawn to scaleto scale
INNER PLANETS
INNER PLANETS
• Terrestrial• Rocky• No rings• Smaller compared to Outer planets
MERCURY• No atmosphere• Temperatures fluctuate wildly• MESSANGER is currently orbiting
Mercury- has completed 282 orbits (so far!)
Sept. 29, 2009MESSANGER
Messenger 9/21/11
• Mapping surface of Mercury
MESSANGER IMAGEAug. 23. 2012
VENUS• THICK atmosphereTHICK atmosphere
– Hot!Hot!– Crushing pressureCrushing pressure
• Rotation is retrogradeRotation is retrograde– Sun rise in west; set in eastSun rise in west; set in east
Pancake volcanoes
MARS• Thin atm.• Windy• Surface similar to Earth
– Volcanoes– Old river valleys- where’s the water?– Best chance to find fossil (life?) in SS
Opportunity and Spirit
• http://marsrovers.jpl.nasa.gov/home/
CURIOSITYlanded Aug. 6, 2012
CURIOSITYCONFIRMS WATER ONCE FLOWED!!
Mars Moons
• Phobos • Deimos
Jovian Planets
• Outer planets• Large• Many moons• all have rings• Made of gas
JUPITER
• Often captures comets/asteroids– Shoemaker/Levy
comet (1994)
Jupiter’s Ring systemFeb. 2007
Jupiter’s New Moons
• Jupiter now has 63 known moons
• 23 moons were discovered in 2002-3 by Earth-based telescopes
http://solarsystem.nasa.gov/planets/profile.cfm?Object=Jupiter&Display=Moons
Saturn’s Rings• Made of Water ice
and dust• Sheppard moons
keep rings in place
Uranian Weirdness
A few of Uranus’s moons
MIRANDAPUCK
ARIELOBERON
Neptune• Very active weather
• Liquid nitrogen volcanoesLiquid nitrogen volcanoes• Cantaloupe terrainCantaloupe terrain• Underground oceans?Underground oceans?• Alien life?Alien life?
Triton-
Planet ?
• 2003 UB313 • Renamed Eris (Xena)
What is a planet?(as of Aug. 2006)
• The IAU said that the definition for a planet is now officially known as "a celestial body that
• (a) is in orbit around a star
• (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a (nearly round) shape and
• (c) has cleared the neighborhood around its orbit."has cleared the neighborhood around its orbit." (not in a swarm of rocks) (not in a swarm of rocks)
Pluto
• Dwarf planet
Lowell Observatorywhere Pluto was discovered
1939
Plutoids
• Dwarf planets beyond Neptune• Established in 2008
Planets, dwarf planets, plutoids
How many moons does Pluto have?
We’re on the way…
• New Horizons spacecraft was launched in Jan. 2006
• Will arrive at Pluto July 2015