How do scientists measure distances in space?
-light years
How do astronomers detect black holes?
-observe x-rays emitted by hot gases from other stars spiralling into black holes
How do unmanned probes explore space?
1-build space craft
2-build and program instruments to record data and send it back
3-pack instruments on board
4-turn on computer and launch probe
some probes fly-by celestial bodies while others enter the atmosphere and are designed to burn up after a while, and others land with rovers to take photos and samples
What are some advantages of unmanned probes?
- no food, water or oxygen needed
- can withstand conditions that are normal lethal to humans
- more instruments can be fitted in with no people taking up room and weighing the probe down
- cheaper: carry less, don’t have to come back to Earth, less spent on safety
- no one gets hurt if something goes wrong
What are some disadvantages of unmanned probes?
- can’t think for themselves (can’t overcome problems that could be disastrous)
- can’t do maintenance and repairs without people
What effects how probes send information back to Earth?
- type of information (samples or data)
- distance fromEarth
How does distance affect how information is sent back to Earth?
- distant objects: have data beamed back
- near objects: probe or people could collect then and physically bring them back to Earth
How does red-shift show the universe is expanding?
- looking at light from different galaxies, we find that the frequencies are lower than they should be
- they’re shifted towards the red end of the spectrum
- measurements of red shift suggest that all distant galaxies are moving away from us very quicky
How does more distant galaxies having greater red-shifts evidence that the universe is expanding?
- more distant galaxies are more red-shifted than near ones
- meaning more distant galaxies are moving away faster than nearer one
- proof that the whole universe is expanding
What is cosmic background radiation
- low frequency microwave radiation, detected by scientists, coming from all direction and all parts of the universe
- strong evidence for the Big Bang
What is the big bang theory?
-all the matter in the universe occupied a space smaller than a pinhead
it exploded: space started to expand (still going)
-the theory helps us guess they age of the universe, but it is very difficult to tell how much speed of expansion has changed since the Big Bang
What are some disadvantages of manned spacecraft?
- need to carry lots of fuel, so heavy and expensive
- lots of food, oxygen and water needed
- temperature regulation required
- toxic gases need to be removed from air
- needs to shield people from radiation in space
- long periods of low gravity cause muscle wastage and loss of bone tissue
- spending ages in a tiny spaces with the same people is psychologically stressful
What happens at the universe expands and cools?
-background radiation ‘cools’ and drops in frequency
