Chapter 6 Flashcards
what does the solar system look like?
- some planets have unusual tilts, large moons, or moons with unusual orbits
- some planets are rocky and some are large hydrogen rich jovian planets
- swarms of asteroids and comets populate the solar system (steroids between mars and Jupiter, oort cloud (even more comets))
planets are are very tiny compared to what?
distances between them
Describe the Sun..
- over 99.8% of solar system’s mass
- 100 times bigger than the sun
- made mostly of Hydrogen and Helium gas (plasma)
Describe Mercury…
- made of metal and rock: large iron core
- desolate, cratered; long, tall, steep cliffs, no moon
- very hot and very cold: 425C during day and 170C at night
- closest to the sun
Describe Venus…
- is it the hottest bc of thick atmosphere
- nearly identical size to earth
- no moon
- extreme green house effect
Describe Jupiter
- father from sun than inner planets
- No solid surface (mostly H/He) like sun
- 300 times more massive than earth
- many moons and rings
- jupiter has 4 galilean moons
Four Galilean moons
- Io ; active volcanoes all over
- Europa; possible subsurface ocean
- Ganymede; Largest moon in solar system
- Callisto- a large cratered “ice ball’
Jovian ring systems
- all four jovian planets
- others have ring particles that are smaller and darker than saturn’s
- jovian ring system just means they have moons
Icy bodies are
many icy bodies like pluto, beyond neptune (kuiper belt objects)
-largest ones are compared to the earths moons (eris is bigger than pluto)
pluto and other dwarf planets
- icy comet like composition
- much smaller than other planets
major planet types
- terrestrial planets are rocky, relatively small and close to the sun
- jovian planets are gaseous, larger, and farther from the sun
why are there two major types of planets?
-most mass is h/he 98%
inside of the frost line
too hot for hydrogen compounds to form ice
- hydrogen compounds stay gaseous
- metals and rocks condense
outside of the frost line
cold enough for ice to condensate
Formation of terrestrial planets
- small particles of rocks and metal were present inside the frost line
- planetesimals of rocks and metal built up as these particles are collided
- they collide and they make planets
gravity draws planetesimals together to form
planets
this process of assembly is called
accretion
formation of jovian planets
- ice could also form small particles outside the frost line
- larger planetisimals and planets were able to form
- the gravity of these larger planets was able to draw in surrounding H and He gases.
where did steroids and comets come from?
- left over from the accretion process
- rocky steroids inside frost line
- icy comets outside frost line
solar system is how old?
4.5 billion years (age dating meteorites that are unchanged)
when did planetesimals bombarded other objects?
late stages of solar system formation
the origin of earths water
icy planetesimals from the outer solar system
how do we explain the existence of our moon and other exceptions to the rules?
- captured them (planetesimals)
- giant impact
Gravitational Tugs
- suns motion depends on the planets tugs
- astronomers who measured this motion around the stars could determine masses and orbits of all planets
- (gravitational change bc planets are changing position)
Astronomic Technique
- detecting planets by measuring the change in a star’s position in the sky
- however these tiny motions are difficult to measure
Doppler Technique
- measuring a star’s doppler shift can tell us its motion towards and away from us
- current techniques could measure motions as small as 1 m/s
first extrasolar planet detected
- short period means small orbital distance
- first planet was discovered in 1995
- monitors 1 star
- moving away from us every 4 days
the bigger the planet
the easier it is to see its light
a transit is when
a planet crosses in front of a star (edge on)
the resulting eclipse
reduces the stars apparent brightness and tells us the planets radius
what can be obtained when there is no orbital tilt?
accurate measurement of planet mass can me obtained
Hot Jupiters
- close to star
- 5 AU from sun
