Chapter 6 The Giant Planets Flashcards
What is heat excess?
If the sun was the only form of energy, then the extra energy required to heat the planets to their temperatures is known as the heat-excess.
This energy must come from internal heating processes.
What does a magnetic field tell us about the gas planets?
The gas planets all contain a magnetic field. This tells us that they likely have a solid core with a liquid outer layer, capable of conducting electricity.
What are the 4 suspected layers of the gas giants?
- Outer layer: hydrogen (H2) and helium (He)
- Helium and metallic hydrogen ( Jupiter and Saturn)
- Icy layer
- Rocky/ icy layer
How do we gather data on the gas giants?
Land based telescopes.
Space based telescopes
Fly by space craft
Orbiters
What is metallic hydrogen?
When under the influence of great pressures and temperatures, the hydrogen atoms form a liquid which is bonded by metallic bonding (positive ions in a sea of elections). This liquid is referred to as metallic hydrogen.
What causes the magnetic field in Jupiter and Saturn?
The magnetic field in both Jupiter and Saturn is caused by the layer of metallic hydrogen. The metallic hydrogen creates a shell around the inner layers that will be in motion due to the heat of the care causing convection currents.
What provides the excess heat in Saturn?
The excess heat could be from the differentiation of helium from hydrogen. The helium droplets release gravitational energy as they fall, and this energy is converted into heat.
Note: helium is valuable in hydrogen at high temperatures and pressures.
What is vibrational spectroscopy?
This is a method for detecting and studying the vibrational frequencies in a molecule. Typically in the infrared spectrum.
Equation for the relationship of pressure, temperature and volume of one mole for an ideal gas
P = ((1.38 x 10^-23)ρT) / m
Where P is pressure in pascals, ρ is density in kg m^-3, m is the average mass of one gas molecule in kg and the constant is in J K ^-1
Do gas giants have oxidising or reducing atmospheres?
They have reduced atmospheres.
They are also reducing atmospheres, meaning iron oxide would eventually be reduced to iron and oxygen. The oxygen would bond with hydrogen to form water.
What kind of atmospheres do the gas giants have?
They have reduced atmospheres.
They are also reducing atmospheres, meaning iron oxide would eventually be reduced to iron and oxygen. The oxygen would bond with hydrogen to form water.
Equilibrium constant equation
For the reaction N2 + 3H2 = 2NH3
The equilibrium constant (K) is found by
K = ([NH3]^2) / ([N2] x [H2]^3)
Where the square brackets represent concentrations and the exponents reflect the quantity of each molecule in the reaction equation.
What is wind velocity in reference to gas giants?
This is used when we want to indicate the direction of motion as well as its magnitude.
Winds in the same direction as the rotation of the planet have positive velocities, wind in the opposite directions have negative velocities.
How is the rotation speed of the gas giants measured?
The magnetic field of the planets is inclined by the rotation axis. This means that the magnetic field varies with the planets rotation. Ions in the ionosphere are accelerated by the magnetic field, however the variation in the magnetic field cause them to release bursts of radiation, who’s interval gives the planets rotation period and thus speed of relation.
What is bite out in reference to measuring orbital periods in gas giants?
Bite out is the period of minimum intensity is regards to the measured radiation that is released by ions from the ionosphere.
What causes the stripes around Jupiters surface?
If Jupiter is a rapidly spinning fluid sphere, then convection in the interior would cause a series of coaxial rotating cylinders at different speeds around the rotation axis. Each cylinder reaches the surface at a different latitude forming the belts.
If the atmosphere is rotating in the same direction on Saturn, why can some windspeeds have a negative velocity?
If the wind speed on the surface is slower than the rotation of the centre of the planet, the wind velocity will appear negative.
Why is the magnetic axis of Uranus and Neptune significantly tipped?
It is suspected that they are significantly tipped because the electricity conducting shell within the planet is thin, which would cause the magnetic axis to tilt.
What causes the magnetic fields of Neptune and Uranus?
It is suspected that under such high temperatures and pressures, water becomes ionised and has dissolved NH4+, H3O+ and OH- ions in the liquid icy material.
What are the clouds made of in the gas giants?
In Saturn and Jupiter, the clouds are mainly ammonia.
In Neptune and Uranus, the clouds are mainly methane, as all heavier compounds (H20, NH4, etc.) are below the visible surface.
Is Jupiter protected from energised particles?
Jupiter is protected from solar wind by its magnetic field, however energised particles stem from IO and other sources within the magnetic field, so it is not safe.
How do we obtain data about the interior of gas giants?
- Measurements of density
- gravitational fields
- magnetic field
- emitted heat
- atmospheric composition
How does the core of Neptune and Uranus differ from that of Jupiter or Saturn?
Jupiter and Saturn are expected to have a rocky core, whereas Neptune and Uranus may have a rocky and icy core that is undifferentiated.
How much energy do the gas giants emit compared to what they receive?
Jupiter, Saturn and Neptune emit more energy than they receive. Uranus emits less energy than it receives.
