P2f-exploring our solar system

Question 1

what is the order of the planets starting with closest to sun?

Answer 1

mercury
venus
earth
mars
jupiter
saturn
uranus
neptune

Question 2

what are galaxies?

Answer 2

large groups of stars

Question 3

what are meteors?

Answer 3

rocks or dust that enter the earths atmosphere

Question 4

what are comets?

Answer 4

balls of rock,dust and ice which orbit the sun

Question 5

what is a centripetal force?

Answer 5

a force that causes a circular motion

Question 6

what provides centripetal force for orbital motion?

Answer 6

gravitational attraction

Question 7

what is a light year?

Answer 7

the distance light travels in a year

Question 8

what are the difficulties of using manned space travel between planets?

Answer 8

spacecraft would need to carry a lot of fuel making it heavy and expensive
have to keep astronauts alive and healthy

Question 9

why is a light year a useful unit for measuring very large distances in space?

Answer 9

distances between galaxies are too enormous and kilometres are too small for measuring them

Question 10

what resources do manned spacecrafts need?

Answer 10

food
water
oxygen
fuel

Question 11

what are some advantages of using unmanned spacecrafts?

Answer 11

• can withstand conditions that would be lethal to humans
• more instruments can be fitted in
• cheaper
• no lives in danger

Question 12

what are some disadvantages of using unmanned spacecrafts?

Answer 12

• cant think for themselves

- cant do maintenance and repairs