P2g

Question 1

How do scientists measure distances in space?

Answer 1

-light years

Question 2

How do astronomers detect black holes?

Answer 2

-observe x-rays emitted by hot gases from other stars spiralling into black holes

Question 3

How do unmanned probes explore space?

Answer 3

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

Question 4

What are some advantages of unmanned probes?

Answer 4

• 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

Question 5

What are some disadvantages of unmanned probes?

Answer 5

• can’t think for themselves (can’t overcome problems that could be disastrous)
• can’t do maintenance and repairs without people

Question 6

What effects how probes send information back to Earth?

Answer 6

• type of information (samples or data)

- distance fromEarth

Question 7

How does distance affect how information is sent back to Earth?

Answer 7

• distant objects: have data beamed back

- near objects: probe or people could collect then and physically bring them back to Earth

Question 8

How does red-shift show the universe is expanding?

Answer 8

• 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

Question 9

How does more distant galaxies having greater red-shifts evidence that the universe is expanding?

Answer 9

• 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

Question 10

What is cosmic background radiation

Answer 10

• low frequency microwave radiation, detected by scientists, coming from all direction and all parts of the universe
• strong evidence for the Big Bang

Question 11

What is the big bang theory?

Answer 11

-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

Question 12

What are some disadvantages of manned spacecraft?

Answer 12

• 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

Question 13

What happens at the universe expands and cools?

Answer 13

-background radiation ‘cools’ and drops in frequency