A11 - Exploring the solar system Flashcards
Name 4 dwarf planets and their location within the solar system:
Asteroid Belt - Ceres
Kuiper Belt - Pluto, Eris, Makemake
What are SSSOs? Give some examples:
-Small Solar System Objects
-asteroids, meteoroids, comets
Describe the structure of a comet:
-nucleus (“dirty snowball”, solid ice and rock)
-coma (gases and dust that envelope the nucleus)
-dust tail (dust that gets left behind the comet because it moves more slowly)
-ion tail (atoms are ionised by the solar wind, and the tail always points away from the Sun)
Comas get brighter/bigger as the comet approaches the Sun
What types of comets are there? Describe both:
short-period - from Kuiper Belt, orbital period of less than 200 years
long-period - from Oort Cloud, orbital period of more than 200 years
note that this is a log scale diagram
Name the 3 major trans-Neptunian regions of space in the solar system:
-Kuiper Belt
-heliosphere (ends between KB and OC, where the solar wind can no longer be felt)
-Oort Cloud
Who discovered Pluto?
Clyde Tombaugh
What was the first planet discovered using a telescope, and who did it?
Uranus, by William Herschel
What is the difference between a meteorite, meteor, and a meteoroid?
-meteoroids are pebble-sized fragments of larger asteroids that orbit the Sun
-meteors are meteoroids that burn up in the atmosphere
-meteorites are meteors that land on the ground
How are meteoroids formed? Describe their structure:
-collisions of asteroids/other bodies
-made of mostly silicate rocks and some iron/nickel
-usually contains a crystalline Widmanstätten pattern of iron/nickel that is only produced after slow cooling over millions of years
Who determined the size of the AU and the absolute size of the solar system? Briefly outline their method:
-Halley, with the Venus transit method
-he realised that the transit of Venus viewed from different latitudes (along the same line of longitude) were slightly different, and had different transit times
Describe the 3 main theories for the origin of water on Earth:
-water and rock was all accreted to form proto-Earth, so it was always here
-smaller icy comets may have been dislodged from their orbits and brought water to Earth after its formation
-Theia brought water from outer Solar System to Earth when it collided with it (formed the Moon too)
Isotope studies of water suggests that less than 10% of water comes from comet impacts
Why is the eye limited for making observations?
-very small aperture
-low sensitivity to light
What is an objective element?
the lens/mirror that collects and focuses the light from an object to form a brighter image, which can be magnified by an eyepiece
Name 2 refracting and 2 reflecting telescopes:
refracting
-Keplerian
-Galilean
reflecting
-Newtonian
-Cassegrain
Describe how a Keplerian refracting telescope works:
-use convex lens (the objective element) to converge light, making a real image on the other side of the lens, close to the principal focus
-look through another convex lens (the eyepiece) to look at the real image, such that the image is less than one focal distance away from the secondary lens
-this forms a virtual image that is much bigger than the object
How is a Galilean refracting telescope different to the Keplerian refracting telescope?
Galilean has a one-sided convex lens, and a concave eyepiece lens
The objective has a flat side to reduce abberations
Ignore the labels on the diagram, just look at the lenses used
Describe how a Newtonian reflecting telescope operates:
-parabolic mirror reflects light from object to form a real image
-the image is reflected off a plane mirror into an eyepiece where it is magnified
How does a Cassegrain telescope work?
-light reflects off the objective parabolic mirror
-reflects off another secondary hyperbolic mirror
-the light goes through a hole in the objective
-magnified by an eyepiece
What is the “light grasp”?
the amount of the light that a telescope can gather, which is directly proportional to the square of the aperture’s diameter
Define field of view, in the context of telescopes:
the angle of sky that can be seen through the eyepiece
What is the resolving power of a telescope? How can it be increased?
-the ability to distinguish between 2 separate objects (eg binary star system)
-increase aperture
-shorten wavelength of the light being observed
θ needs to be minimised to increase angular resolution, which would need the diameter to increase or the wavelength to decrease
How can the magnification of a telescope be calculated?
the magnification is the focal length of the objective element, divided by the focal length of the eyepiece
When referencing a telescope’s specs, what should you always mention?
explicitly say what the telescope has (eg large diameter, therefore the telescope has a large aperture)
Give comparative answers if necessary
Why were Galileo’s observations important? Name 2 pieces of evidence he collected:
-he showed that the Sun was at the centre of the Solar System (heliocentric)
-he saw that Venus had phases
-he saw that moon’s orbited Jupiter (the Galilean moons)
Venus’s angular size would also change, meaning it was getting closer and further in its orbit around the Sun
Give some advantages of using reflecting telescopes:
no chromatic abberations - only happens in lenses when different λ refract differently
easier to have longer FL - it’s harder to make thin lenses
larger objective mirrors than lenses - lenses must go on the front end of the telescope as opposed to the rear, so it is front-heavy
combine multiple mirrors - makes a much bigger aperture
Name 4 types of space probes:
-fly-by
-orbiter
-impactor
-lander
Describe an example of a fly-by probe:
New Horizons - outer Solar System
-discovered Pluto’s atmosphere
-recorded a volcanic eruption on Io (Jupiter’s moon), first one to be recorded that wasn’t on Earth
Describe the pros and cons of a fly-by probe:
pros
-lots of measurements/images can be taken and sent back to Earth
cons
-can only be flown once, so not all parts of the bodies can be observed/analysed
Name 2 orbiter probes and their destinations:
-Juno (Jupiter)
-Dawn (Vesta + Ceres, in the Asteroid Belt)
Describe what Juno discovered:
discovered storms at Jupiter’s North Pole, and found that its magnetic field is much stronger than originally thought
Describe what Dawn discovered:
-Ceres once had surface water
-Vesta had hydrated and carbon-rich material due to impacts with other bodies
Describe the pros and cons of an orbiter probe:
pros
-entire body can be observed/analysed as there is more time to gather data
cons
-lots of fuel needed to get it into an orbit
-data that can be obtained from space is limited
Describe an example of an impactor probe:
Deep Impact - Tempel 1 (comet)
-found powdered water ice that sheltered complex organic compounds beneath
Describe the pros and cons of an impactor probe:
pros
-passes through body’s atmosphere and can dislodge material onto its surface to analyse compositions
cons
-has to send data back through a relay probe in space which has to be perfectly positioned at the right time, as impacts can be unpredictable
Describe an example of a lander probe:
Philae - comet 67P/Churyumov Gerasimenko
-2 comets can combine to form one, and its topography is quite complex
-surface not covered in ice, but the ice would start erupting as it approached the Sun
Describe the pros and cons of a lander probe:
pros
-can make more detailed observations/photos/experiments
cons
-low success rate (difficult/expensive to land softly)
-can only examine the area close to the landing point
Why might the energy requirements for sending an orbiter to Europa be much greater than be put into Earth’s orbit?
Apart from the fact that it is further
it must reach Earth’s escape velocity
How does a rocket move?
-Newton’s 3rd Law (every action (force) has an equal and opposite reaction)
-fuel heats up gas which expands rapidly
-the rocket exerts a downwards force on the gas
-the gas exerts an equal upwards force on the rocket
-rocket accelerates upwards
Give some benefits of having manned space missions:
-more complex experiments can be conducted
-last minute changes can be made with no delay
-can repair equipment more easily
What are the disadvantages of manned missions?
-ionising radiation exposure risk
-larger payloads required, more expensive
-people are weak and not capable of surviving high accelerations, meaning travel times must be longer
-psychological problems caused by living in confined areas for extended periods of time
-lack of gravity causes muscle atrophy (wastes away) and bone weakening
Describe the main features of the Apollo space program:
-Apollo 11 landed in 1969 (Neil Armstrong and Buzz Aldrin walked on surface whilst Michael Collins stayed inside the command module)
-12 astronauts walked on the surface of the Moon over 3 years
-left a set of experiment packages on the Moon (Apollo Lunar Surface Experiments Package, ALSEP)
Michael Collins took this photo, which contains every human being, alive or dead, except himself.
