Solar Systems Flashcards
Give some differences between terrestrial and jovian planets.
Terrestrial: Less than 2AU from Sun
Small
Mostly rocky materials
High Density
Jovian: More than 5AU from Sun
Large
Mostly light H and He
Low Density
T or F. Mercury has no atmosphere.
True.
What is the primary element in the atmosphere of Venus and Mars?
Carbon Dioxide.
Formula for kinetic energy of a gas atom or molecule.
E = ( 3 / 2 )* (B) * T
E = energy
T = temperature
B = Boltzmann Constant
Formula for average speed of a gas atom or molecule.
root( 3 * (B) * T / m)
where T = Temperature
m = mass
B = Boltzmann Constant
T or F. All the jovian planets have rings.
True.
How are planetary rings formed?
When a satellite passes inside the roche limit, the tidal forces overwhelm the gravitational forces that hold the satellite together. The fragments are spread about the planet by Kepler’s third law.
How is the Roche limit of a planet calculated?
2.4 * radius
Name two features of Jupiter.
Aurorae on its poles
Great red spot
T or F. Jupiter’s atmosphere does not seem to suffer significant changes over the years.
False.
T or F. The smallest size of the Great Red Spot is one earth diameter.
True.
What is unique about Uranus?
Its axis of rotation is fully tilted with the equatorial plane perpendicular to the orbital plane.
T or F. Despite its rotation being tilted, all of Uranus’ satellites still orbit around Uranus along the orbital plane.
False.
Why are features not easily seen on the surface of Uranus?
Features form in the troposphere closer to the surface.
T or F. If you wanted to see planets in Dublin’s night sky you should look at the ecliptic?
True.
T or F. From the terrestial planets, only Venus and Earth have atmospheres.
False.
T or F. Venus has no magnetic field.
True.
T or F. Mars and Mercury have magnetic fields though weak.
True.
T or F. The magnetic field of Earth is of moderate strength like Mars.
False.
Name four methods for detecting exoplanets.
Radial velocity or ‘stellar wobble’ method.
Astrometric method
Transit Photometry
Direct Imaging
Explain how radial velocity method works.
If a star has companions, then the wavelengths of the stars spectral lines get Doppler shifted, since the star has motion relative to the centre of mass of the solar system.
The magnitude of the wobble determines the companion minimum mass, the period determines the semimajor axis.
Explain how transient method works.
When the planets passes in front of the star, the amount of dimming tells us the planet’s diameter, additional absorption features reveal the composition of its atmosphere.
When the planet moves behind the star the amount of infrared dimming tells us the planet’s surface temperature.
What is the habitable zone for our solar system?
0.95 Au to 1.37AU
T or F. The transient method can help us measure mass, radius, density, orbit and atmosphere of a planet around a star.
True.
T or F. The habitable zone is a fixed range of distance for any one star.
False.
As temperature/size of star fluctuates so does this zone.
Give the four conditions for a dwarf planet.
a) is in orbit around the Sun
b) nearly round shape
c) has not cleared the neighborhood around its orbit
d) Is not a satellite
What is unique about Pluto?
Pluto is a dwarf planet which forms a binary system with Charon a moon, where Charon’s gravitational pull is not negligible compared to Pluto’s.
Size range for asteroids.
between few kilometres up to 1000km in diameter.
What does it mean for a comet to be active?
Means near the sun.
What is sublimation?
Heating of icy nucleus to form coma, ion tail created by solar wind and dust tail created by solar wind and sunlight.
T or F. Comet tails always point away from the sun.
True.
What is a prograde orbit? Which comet is more likely to have a prograde orbit near ecliptic plane?
When orbitting body moves with same direction of rotation as what it orbits.
Short-period.
T or F. Retrograde orbit comet originates in Oort Cloud.
True.
Age range for short period comet.
< few centuries
What is a sungrazing comet?
Comet with perihelion at less than 0.01AU
How far does the Oort cloud extend?
50000AU
Define meteoroid.
A meteoroid is a small object moving across the Solar System.
Define meteor.
A meteor is the brief flash of light that is visible when a meteoroid enters Earth’s atmosphere. For meteoroids less than 10m wide heat vaporises it.
What is a meteorite?
Piece of rock that has survived the descent through Earth’s atmosphere and has reached the ground.
What is meteor swarm?
The residual dust and rock fragments left by the tail of a comet are called meteor swarm. Lead to meteor showers.
T or F. Dwarf planets have in common that they have orbital inclinations greater than that of the main planets.
True.
What are the Kirkwood gaps?
Regions with fewer asteroids.
Formula showing how we calculate planets radius using transient method.
fraction of light blocked = (R planet / R star )^2
T or F. Jovian planets spin much slower than Earth.
False.
Why do the Jovian planets primarily retain their atmospheres?
Large mass
What is the name used to describe the dark bands encircling Jupiter?
Belts
Why has direct imaging found so few exoplanets?
Exoplanets are faint and are usually close to their parent stars.
Space telescopes looking for transiting planets look for small drops in brightness; these drops are:
Less than 0.01%
The habitable zone is the area around a star where:
temperatures are suitable for planets to have liquid water
When looking for the radial velocity changes or ʺwobblesʺ detected due to Doppler shifts, which mass combination is most likely to be detected?
Question options:
high mass star, high mass planet
a high mass planet, the mass of the star is irrelevant
low mass star, high mass planet
low mass star, low mass planet
high mass star, low mass planet
low mass star, high mass planet
Neptune and Uranus have a bluish tint because:
Question options:
their atmospheres contain hydrogen and helium
at their distances, the Sun appears blue, the red absorbed by dust in the ecliptic
their atmospheres contain methane, which absorbs red light
ammonia ice reflects blue light better than any other color.
they are far away and distance makes objects appear bluish
their atmospheres contain methane, which absorbs red light
Why is it easier to discover transiting exoplanets, especially small ones, with a telescope in space than with a ground-based telescope?
Question options:
A.- Because of the longer exposure times available in space
C. - Because we can build larger telescopes
B.- Because of the lack of atmosphere
A and B
B and C
The original statement is wrong, ground-based telescopes are better
A and B
A moon that goes inside the Roche Limit will:
Question options:
become a planet.
get heated by the strong magnetic fields.
be torn apart by the planetʹs tidal forces.
escape its planetʹs gravity.
collide with a major satellite.
get heated by the strong magnetic fields.
