P1.3

Question 1

What does the solar system loom like?

Answer 1

can see some planets with naked eye- look like stars but different
planets orbit around stars and often have smaller moons close to them and orbiting around them
planets vary in size - mercury smallest and Jupiter biggest
Neptune furthest from sun

manned spacecraft can reach moon in 3days and potentially Mars in 9 months
Neptune would take at least 12 years

Question 2

What is a galaxy?

Answer 2

sun in milky way galaxy

collection of billions of stars - distance between them is hundreds of times greater than distance between planets in solar system

billions of galaxies make up universe
distance between galaxies millions of times greater than distance between stars in a galaxy

Question 3

What is SETI?

Answer 3

Search for Extra Terrestrial Intelligence
scientists looking for narrow bands of radio wavelengths coming to earth from space and looking for meaningful signals in ‘noise’ - signals could have come from a transmitter and noise from other things like giant stars

get help from public as takes a long time to analyse - can download screensaver that analyses radio waves

haven’t found anything in 50 years but now looking for possible laser signals in space

Question 4

How can robots and probes collect data and samples?

Answer 4

spacecraft carrying probes sent to investigate planets and moons in solar system - probes carry instruments that continuously record data on conditions like temperature. data sent back to Earth on microwave or radio signals

robots can take photos and collect soil and rock samples to analyse

scientists still have to work out what data means

Question 5

What are some examples of SETI work?

Answer 5

1976 Mars Viking landers - took soil samples with robotic arm and carried out experiments on soil to see if any
signs of life. data sent back to Earth using radio signals

also look at comets and asteroids as well as planets
2003 Hayabusa spacecraft sent to collect dust samples

Question 6

How do scientists look for signs of life?

Answer 6

Earth based telescopes
other remote-sensing techniques
do these before spending money on sending robots/people closer

search for planets with suitable conditions for life
too expensive and impractical beyond solar system as distances too large

Question 7

What are some of the problems with using telescopes?

Answer 7

if trying to detect light the Earth’s atmosphere gets in the way
light pollution makes it hard to pick out dim objects
air pollution can reflect and absorb light coming from space

Question 8

What can be done to solve problems with using telescopes?

Answer 8

for best possible view telescopes should be put on top of a mountain and away from cities
to avoid atmosphere problem, put telescope in space - enables you to see objects a lot fainter than can be seen unaided from Earth

Question 9

How are optical telescopes useful?

Answer 9

earliest telescopes
detect visible light though many objects not detectable this way
used to look at objects close by and in other galaxies

e.g cygnus A is a nearby galaxy - through optical telescope, seen as small blob surrounded by stars

Question 10

How are Radio telescopes useful?

Answer 10

responsible for discovery of CMB radiation, helped scientists learn about origins of universe

e.g cygnus A seen as two radio jets moving away fro centre of galaxy in opposite directions - creates two massive ‘lobes’ of hot radiation

Question 11

How are X-Ray telescopes useful?

Answer 11

good way of seeing violent. high temperature events in space e.g exploding stars

Question 12

How have telescopes improved?

Answer 12

bigger telescopes - better resolution, gather more light - can see things we couldn’t before as they were too faint

improved magnification - can look further into space,more galaxies discovered
important as scientists can learn more about their life cycle
e.g pictures taken by Hubble Space Telescope show galaxies at life stages - used so scientists can learn more about how galaxies formed and evolved

Question 13

Why are computers used alongside modern telescopes?

Answer 13

computers create clearer and sharper images, makes it easy to capture pictures for analysis

makes it possible to collect and store huge amounts of data 24/7 without relying on humans

make it quicker and easier to analyse data

Question 14

What is a spectrometer and how is it used?

Answer 14

a tool used to analyse light given out by stars and galaxies

it works by a telescope directing a beam of light into it through a slit - this diffracts light and splits it up into a spectrum

Question 15

What is an absorption spectra?

How can it be used?

Answer 15

light spectra from stars and galaxies contain dark lines caused by light at wavelengths being absorbed
e.g by elements in stars atmosphere

it can be used to work out what stars and galaxies are made of as each element has it’s own

some have bright lines (emission) - these are caused by extra light being emitted at wavelengths

spectra for galaxies further away appear more red than they should

Question 16

How do you make a spectrometer using a CD?

Answer 16

make 1mm wide slit on one end of a box - where light comes through
make slit for CD at 45 degree angle on side of box
make a hole to look through by cutting a slot about 2cm by 6cm
put CD in box with underside (rainbow side) is facing where you’ll look through

hold up the box so it lets in light from the source through the slit
you should be able to see a visible spectra

different light sources will show different looking spectra

Question 17

What might you see through a spectrometer?

Answer 17

continuous spectrum - no light absorbed so no dark lines

bright lines - show wavelengths of light emitted

dark lines - show wavelengths that weren’t emitted

Question 18

What is the main life cycle of all stars?

Answer 18

initially form nebulas- clouds of dust and gas
force of gravity makes the dust and gas spiral together. gravitational energy converted to heat energy, temperature rises
when temp high enough, hydrogen nuclei undergo thermonuclear fusion to form helium nuclei. give out massive amounts of energy and star born
star enters long stable period where the heat created by nuclear fusion provides outward pressure - balances force of gravity, everything pulled inwards
eventually hydrogen in core begins to run out - star swells into red giant. becomes red as surface cools

Question 19

What is the life cycle of a small star?

Answer 19

small star e.g sun becomes unstable, ejects outer layer of dust and gas as planetary nebula
leaves behind hot, dense,solid core called a white dwarf - cools and eventually dissapears

Question 20

What is the life cycle of a large star?

Answer 20

glows brightly - undergoes more fusion and expands and contracts, forms heavier elements in nuclear reactions
eventually explodes in a SUPERNOVA
exploding supernova throws outer layer of dust and gas into space - leaves dense core called a Neutron Star
if the star is big enough,becomes a black hole

Question 21

What is red shift?

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Answer 21

when look at light form other galaxies, frequencies appear lower than they should be - the galaxies are shifted towards the red end of the spectrum

measurements suggest all galaxies moving away from us more distant galaxies have a greater red shift as moving away faster

provides evidence for the big bang theory and steady state theory

Question 22

What is CMB radiation?

Answer 22

low frequency EM radiation from all parts of universe bu mainly in microwave part of EM spectrum

evidence for big bang theory - as universe expands and cools , radiation ‘cools’ and drops in frequency
big bang only theory to explain CMB radiation so is currently most accepted model by scientists

Question 23

What is the ‘Big Bang’ Theory

Answer 23

matter and energy in universe compressed into small space then exploded and started expanding
expansion still happening and we can use the current rate to estimate the universe’s age
estimated it happened about 14 million years ago

Question 24

What is the steady state theory?

Answer 24

universe always existed as it is now and always will
based on the idea that the universe appears pretty much the sameeverywhere

explains apparent expansion and red shift by suggesting matter is created in spaces as the universe expands