A11 - Exploring the solar system

Question 1

Name 4 dwarf planets and their location within the solar system:

Answer 1

Asteroid Belt - Ceres

Kuiper Belt - Pluto, Eris, Makemake

Question 2

What are SSSOs? Give some examples:

Answer 2

-Small Solar System Objects

-asteroids, meteoroids, comets

Question 3

Describe the structure of a comet:

Answer 3

-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

Question 4

What types of comets are there? Describe both:

Answer 4

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

Question 5

Name the 3 major trans-Neptunian regions of space in the solar system:

Answer 5

-Kuiper Belt

-heliosphere (ends between KB and OC, where the solar wind can no longer be felt)

-Oort Cloud

Question 6

Who discovered Pluto?

Answer 6

Clyde Tombaugh

Question 7

What was the first planet discovered using a telescope, and who did it?

Answer 7

Uranus, by William Herschel

Question 8

What is the difference between a meteorite, meteor, and a meteoroid?

Answer 8

-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

Question 9

How are meteoroids formed? Describe their structure:

Answer 9

-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

Question 10

Who determined the size of the AU and the absolute size of the solar system? Briefly outline their method:

Answer 10

-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

Question 11

Describe the 3 main theories for the origin of water on Earth:

Answer 11

-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

Question 12

Why is the eye limited for making observations?

Answer 12

-very small aperture
-low sensitivity to light

Question 13

What is an objective element?

Answer 13

the lens/mirror that collects and focuses the light from an object to form a brighter image, which can be magnified by an eyepiece

Question 14

Name 2 refracting and 2 reflecting telescopes:

Answer 14

refracting
-Keplerian
-Galilean

reflecting
-Newtonian
-Cassegrain

Question 15

Describe how a Keplerian refracting telescope works:

Answer 15

-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

Explanation

Question 16

How is a Galilean refracting telescope different to the Keplerian refracting telescope?

Answer 16

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

Question 17

Describe how a Newtonian reflecting telescope operates:

Answer 17

-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

Question 18

How does a Cassegrain telescope work?

Answer 18

-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

Question 19

What is the “light grasp”?

Answer 19

the amount of the light that a telescope can gather, which is directly proportional to the square of the aperture’s diameter

Question 20

Define field of view, in the context of telescopes:

Answer 20

the angle of sky that can be seen through the eyepiece

Question 21

What is the resolving power of a telescope? How can it be increased?

Answer 21

-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

Question 22

How can the magnification of a telescope be calculated?

Answer 22

the magnification is the focal length of the objective element, divided by the focal length of the eyepiece

Question 23

When referencing a telescope’s specs, what should you always mention?

Answer 23

explicitly say what the telescope has (eg large diameter, therefore the telescope has a large aperture)

Give comparative answers if necessary

Question 24

Why were Galileo’s observations important? Name 2 pieces of evidence he collected:

Answer 24

-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

Question 25

Give some advantages of using reflecting telescopes:

Answer 25

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

Question 26

Name 4 types of space probes:

Answer 26

-fly-by
-orbiter
-impactor
-lander

Question 27

Describe an example of a fly-by probe:

Answer 27

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

Question 28

Describe the pros and cons of a fly-by probe:

Answer 28

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

Question 29

Name 2 orbiter probes and their destinations:

Answer 29

-Juno (Jupiter)
-Dawn (Vesta + Ceres, in the Asteroid Belt)

Question 30

Describe what Juno discovered:

Answer 30

discovered storms at Jupiter’s North Pole, and found that its magnetic field is much stronger than originally thought

Question 31

Describe what Dawn discovered:

Answer 31

-Ceres once had surface water
-Vesta had hydrated and carbon-rich material due to impacts with other bodies

Question 32

Describe the pros and cons of an orbiter probe:

Answer 32

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

Question 33

Describe an example of an impactor probe:

Answer 33

Deep Impact - Tempel 1 (comet)
-found powdered water ice that sheltered complex organic compounds beneath

Question 34

Describe the pros and cons of an impactor probe:

Answer 34

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

Question 35

Describe an example of a lander probe:

Answer 35

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

Question 36

Describe the pros and cons of a lander probe:

Answer 36

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

Question 37

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

Answer 37

it must reach Earth’s escape velocity

Question 38

How does a rocket move?

Answer 38

-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

Question 39

Give some benefits of having manned space missions:

Answer 39

-more complex experiments can be conducted
-last minute changes can be made with no delay
-can repair equipment more easily

Question 40

What are the disadvantages of manned missions?

Answer 40

-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

Question 41

Describe the main features of the Apollo space program:

Answer 41

-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.