Schol SPACE Flashcards
What gives a planet a magnetic field?
Mobile conductive fluids.
Eg. Earth’s outer core of molten iron and nickel
What is implied if a planet has a strong magnetic field?
It has a large liquid core
The core is rich in metals
High rotation rate
What does earth’s magnetic field do?
protects the earth from high levels of radiation 
Prevents erosion of the atmosphere
How does the magnetic field affect solar wind?
Solar wind = stream of energetic charged particles from the sun
Mag field deflects the charged particles. Channels some charged particles into the Van Allen radiation belts.
Solar winds cause the magnetic field to be compressed on the side closest to the sun, and extend far out away from it.
Lack of magnetic field results in…
Eg Mars
Solar winds not deflected, strips away atmosphere so it is very thin. Low surface pressure
Why does venus and Mercury have a weak magnetic field
Both rotate slowly (compared to earth)
No evidence of tectonic activity on Venus
Weak mag field on Mars suggests circulation of a molten iron core (due to eccentric orbit and large tidal forces)
Define ‘locking’
Give an example
An object has the same rotational period as it’s orbital period
Eg moons generally have synchronous rotation with the planet (1:1 tidal locking)
Tidally locked planets in the solar system
Generally only planets within close proximity of a star can be tidally locked
Mercury 3:2, as orbit is eccentric
(Rotates 3 times for every 2 orbits)
Define habitable zone
Area around a star where the temp allows LIQUID water to exist on the surface of a planet
Depends on the type of star (eg red dwarf zone is closer to the star, likely to be tidally locked)
Define tidal flexing
Occurs when interior of orbiting body subjected to FRICTIONAL FORCES because of the gravity of the thing it’s orbiting.
Effects of tidal flexing on moons around gas giants (Jupiter)
Huge planet, large grav forces.
Cold, but friction creates heat… perhaps some moons are habitable
Effects of tidal flexing are amplified if orbit is eccentric.
Eg tidal bulges on Io (Jupiter’s closest moon). Close to planet, large bulge.
Tidal locking and Io
Elliptical orbit and huge tidal forces. Variation of orbit causes variation in flexing, causes further friction.
Causes frictional heating of rocks into magma and VOLCANISM on the surface.
The most volcanically active body in the solar system due to huge tidal forces from Jupiter AND other large moons (Europa, Ganymede)
Tidal locking and Enceladus
Icy, high albedo. BUT may have ocean under ice because of heating by tidal flexing, keeps water under the surface in liquid form.
Evidenced by plumes of water vapour and salty ice.
Possibility of geothermal vents due to flexing
—> extremophiles: potential for Chemotropic (and halotrophic) life forms… similar to those around geothermic vents. Plumes of water contain CO2, source of carbon.
Tidal flexing and Europa
Thick ice on surface.
May be liquid water ocean under ice
Possibility of underwater volcanoes as a result of tidal flexing
Requirements for life
Conditions that allow liquid water to be present
(warmth from sun/geothermal activity/tidal flexing)
A carbon source (C compounds for catabolism/anabolism)
Energy source to ‘fix’ inorganic C to organic. (Photosynthesis / chemosynthesis)
Protection from harmful radiation, and TIME for life to evolve (4 billion years for earth)
Define chemosynthesis
Instead of energy from the sun, organisms use energy from oxidation of inorganic compounds to fix it into organic molecules.
Eg. Methanotrophes use CH4.
in deep sea vents oxidise H2S as an energy source, CO2 to C.
What are extremophiles?
Microbes that live in extreme conditions on earth
(Intense heat, cold, pressure, acidity, dryness)
Prokaryotic organisms
Bacteria, archaea (many extremophiles in the Archaea domain)
Describe the features of Titan and possibility of life
Biggest moon of Saturn and the solar system.
The only other object with solid land, flowing rivers and lakes of liquid METHANE
—> methanotropic (methane using) or methanogenic (methane producing) reactions could occur.
Possibility of syntrophic relationship.
Methane based organisms (due to low temp) rather than water based.
Organic compounds are less soluble in CH4 than water, concentration gradients difficult to set up.
Specialised active-transport across membranes
What are two ways that a body can gain an atmosphere?
Solar nebula - primary atmosphere. Mostly H and He.
Very light, required large gravity, only gas giants kept much of the early atm.
Volcanic - secondary atm.
Gases from the interior of the planet released.
Heavier H2O, CO2 easily retained
How is an atmosphere lost?
Size - smaller gravity, lower escape velocity
Heat - more Ek, more molecules escape
Impact - large impact can blow away atm (like Mars)
Loss to surface - dissolved or condensed
Solar wind - lack of mag field strips atm away
what are coronal mass ejections
giant solar flares
cause strong geomagnetic storms
may affect electronics on earth
what are sunspots
small, dark regions on the sun’s surface containing strong magnetic fields
cooler than the rest of the sun
number varies over an 11 year cycle
describe a lunar eclipse
Earth completely blocks the moon from the sun
moon is located in the umbra
some sunlight is bent through earth’s atmosphere, giving the moon a coppery glow
Mercury main features
No atmosphere
Very slow rotation
–> very hot on one side, very cold on the other (rocky surface absorbs / loses heat quickly)
Venus main features
very high surface temp due to thick atmosphere, 97% CO2
Thick dense clouds made of sulphuric acid and CO2
backwards rotation
moon main features
very big for earth’s size
same side faces Earth – locked
no atmosphere
very little water
many visible craters - no atm = no erosion
Mars main features
may have had liquid water (river beds)
thin atmosphere, 95% CO2, some methane
strong winds
extinct volcanoes and Valles Marineris show possible tectonic activity
two moons – possibly captured asteroids
also on a tilt – has seasons
Jupiter main features
Mostly H
high speed winds
Great Red Spot
faint rings
