Unit 4 Flashcards
Mercury (brief)
Terrestrial planet
more typical of the inner planets than watery surface of earth
No atmosphere
Dangerous place
There is a lot of cratering records in our solar system
on planets and moons (natural satellites)
Terrestrial planets
when these planets formed they were hot and molten (liquid rock)
Differentiation acured
Differentiation
As planets cool the denser material sinks towards the center of the planet and forces lighter materials to float to the surface
The outer solar system
4 giant planets
* Jupiter
* Saturn
* Uranus
* Neptune
While harder to reach still the subject of many successful missions
Planet Types
Terrestrial
* small and rocky
* orbit close to the sun
Jovian
* much larger and gaseous
* orbit much further out
Jovian Worlds
Mostly made of hydrogen and helium, gases we see in the sun
when we see these planet it is their atmosphere we observe
Many hydrogen compounds in the atmosphere
Ganymede
Jupiters Moon
Largest satellite
Jovian vs Terrestrial planets
A big difference between Jovian and Terrestrial planets is the number of natural satellites
Jovian worlds have lots more satellites Jupiter has 95 orbiting around it
The terrestrial planets have few if any satellites
Impact today
In 1994 Jupiter sustained impacts from over 20, 1km size rocks
* moving at over 60 km/s from gravitationally disrupted comet
If any were to hit Earth, significant devastation would occur
Dwarf planet
Pluto First discovered as a planet
* Then late was proven to be considered a Dwarf planet (Smaller than our moon)
* Has active ice volcanoes
Unlike planets we are not sure how many dwarf planets exist
this is a new category of objects (2006)
Rings
All 4 Jovian worlds possess rings
* some better developed (brighter and larger)
Made up of rock and since, normally only a few centimeters in size but can range up to meters
Asteroids (Minor planets)
Are everywhere
Number in the millions
some are 100 Km in diameter
small pieces of rock that do not become part of planet during the solar system formation 4.5 billion years ago
Comets
Also leftover materials from the formation of the solar system
only a few kilometers in diameter
different from asteroids
* they contain a lot more volatile materials (water, ice, methane, carbon dioxide)
* when heated they generate very bright and long tails
Age determination
Determined by counting the number of creates in a given area
* More means older
* Only works if the surface is not geologically active
Using radioactive dating
* Every radioactive element has a half-life
* Original material is often called the parent, and what it decays into is the daughter