Chapter 7: The Solar System Flashcards
Beginning formation of solar system
- nebula initially (pre-stellar nebula) (pre solar nebula)
- star is forming in centre but lots of material in disk outside in which planets form
- pressure from star turning on sweeps has out of orbit
- 100 million years later the solar system was fully formed
Aggregation
Rocky planetesimals formed from pieces sticking together
-like making a snow man
Differentiation
Different material will form or unform based on how far from the sun it is
Like Earth firms silicates, rocky materials, water
Whereas Saturn has ammonia ice
Age of solar system
About 5.6 billion years
Composition of solar system
- Sun
- Planets (8)
- Asteroids (asteroid belt)
- Comets (Oort cloud)
- Dwarf planets
Planets motion
- length of years depends on distance from sun
- pos rotation means same direction as orbit of sun opposite is neg
- most planets are tilted compared to orbit
- inclination to orbital plane as well (Mercury has largest inclination)
Terrestrial planets
- Earth, Mar, Venus, Mercury
- rocky, dense, small, few satellites (moons)
Mars moons
Phobos and Deimos
Jovian planets
- Jupiter, Saturn, Uranus, Neptune
- large, gaseous, low density, many moons
- gas giants
Impact craters
- need rocky surface and little atmosphere to survive
- Earth Barringer (1.2 km)
Rings
Saturn has very obvious rings, but all the Jovian planets have rings
-no terrestrial planets have rings
Comets
- found in Oort belt and Kuiper belt
- most are very far away and can not be observed
- they are distributed in random orbits and are left overs from formation of solar system
- orbits both eccentric and highly inclined
- not very big (1km) but tail can be 1Au
Comets composition
-solid core: nucleus make of different ices
-coma: when the ice is evaporating around nucleus
-Tail: always points away from sun due to radiation pressure from sun
(May have 2 tails one from dust which is radiation and has pressure and one from gas)
Meteors
- are solid and rocky in composition
- are basically shooting stars, very small particles that skid across the atmosphere and burn up
- mostly due to chunks left from comets passing by
Meteroites
- A solid object that actually hits the ground
- Bigger then meteors
- Hoba
- they are either rocky Chondrites or Iron
Asteroids
- larger lumps of rocks in space
- usually not spherical, no atmospheres or moons
- most in main asteroid belt between Mars and Jupiter
- didn’t end up making a planet
Pluto
- a planetary oddity
- orbit crosses Neptune’s orbit
- highly inclined
- resonant orbit which Neptune 3:2
- more terrestrial (small, no rings, few moons)
- moons: Charon, Hydro, Kerberos, Styx
- Pluto and Charon considered dwarf planet pair
Centaurs
Objects found mostly between Saturn and Neptune
-mostly rocky but sometimes have coma and tail
Trans Neptunian Objects
Anything past Neptune
-Plutinos: anything near Pluto
-Kuiper belt: broad range
-scatter disk: fewer of them, scattered
—> Eris: larger then Pluto
-lots of TNOs being discoveredClassifying planets
- has to orbit the sun
- is large enough to be round under its own gravity
- has cleared its lane of other material
So what is Pluto?
A dwarf planet
- has an orbit
- large enough to be round
- but has not cleared its path
-Doppler shifts detection methods
- the star in the middle will move around a common centre of gravity
- take a spectrum and create a light curve vs velocity
- biased to hot Jupiter’s (large and close)
Advantages and disadvantages of Doppler shifts
•Advantages:
-false detections unlikely
- orbits do not need to be edge on
- very successful
•Disadvantages:
-uncertainty in inclination angle of mass
- bias towards high mass and close
- requires larger telescopesTransits
- measuring brightness of orbit as function of time
- have repeated transits to know something is orbiting
- light curves provide a measurement of radius and other parameters
Advantages and disadvantages of transits
•Advantages:
-see many stars
- smaller telescopes
- radius and possibly atmosphere determined
•Disadvantages:
- system needs to be edge on
- lots of false alarms
- needs Spectroscopic confirmationDirect imaging
- taking a photo of the exoplanet
- very hard due to how bright stars are
Advantages and disadvantages of Direct imaging
•Advantages:
-see pictures of exoplanets
•Disadvantages:
- very hard observationally
- must prove it’s a planet
- braised towards high mass/ large separationHabital zone
- is the place where liquid water can form
- closer to low mass stars and farther from high mass stars for right temperature
- Kepler is making a big difference in tally of Earth sized planets
- 17% stars in Milky Way host an Earth sized planet - 17 million Earths
