space

Question 1

what are comets?

Answer 1

-large objects made of dust and ice that orbit the sun
-they have elliptical orbits

Question 2

what are asteroids?

Answer 2

-large objects made of rock and metal that orbit the sun

Question 3

what is a galaxy?

Answer 3

-a collection of billions of stars that all orbit the same point

Question 4

what is a satellite + give examples

Answer 4

-an object that orbits a planet
-moons and the international space station

Question 5

what is a natural satellite + give an example?

Answer 5

-a satellite that is not man-made
-a moon

Question 6

what is an artificial satellite? give an example

Answer 6

-a satellite that is man-made
-international space station

Question 7

what kind of orbits do planets have?

Answer 7

-elliptical orbits

Question 8

what is the solar sstem?

Answer 8

-it consists of the sun and the objects that orbit it, including planets and moons etc

Question 9

what is a nebula?

Answer 9

• a large cloud of dust and gas

Question 10

what happens when a nebula becomes very large?

Answer 10

-gravity pulls the particles of dust and gas together to form a protostar

Question 11

what happens when a protostar becomes very large?

Answer 11

-gravity becomes stronger which pulls the particles closer together and increases the temperature and pressure
-at some point nuclear fusion will start fusing hydrogen nuclei together

Question 12

what do we call a protostar once nuclear fusion starts?

Answer 12

-a main sequence star

Question 13

which two forces are in balance in a main sequence star?

Answer 13

-the energy released from nuclear fusion creates an outward force that balances the inward force from gravity

Question 14

which elements undergo nuclear fusion in a main sequence star?

Answer 14

-hydrogen nuclei fuse to make helium nuclei

Question 15

how long does a main sequence star last

Answer 15

-until all of the hydrogen is used up
-which could be millions or billions of years

Question 16

what two things could a main sequence star become once it runs out of hydrogen?
-what determines which it becomes?

Answer 16

-if it is relatively small, it will become a red giant
-if it is relatively large, it will become a red super giant

Question 17

for a red giant, what are its final phases of the star’s lifecyle?

Answer 17

-the red giant will become a white dwarf, which will then become a black dwarf as it cools

Question 18

which elements can be formed in the red giant or red super giant phase?

Answer 18

-elements heavier than helium, up to iron on the periodic table

Question 19

for a red super giant , what happens next in the star’s lifecycle?

Answer 19

-it will explode in a supernova

Question 20

which elements can be formed in a supernova

Answer 20

-supernovas form elements heavier than iron, which are fired across the universe as they explode

Question 21

what two things could form after a supernova and what determines which is formed?

Answer 21

-if the star was large, it would condense to form a neutron star
-if it was very large, it would collapse to form a black hole

Question 22

what is a neutron star

Answer 22

-an extremely dense mass of neutrons

Question 23

what is a black hole?

Answer 23

-a region where gravity is so strong no particles, or even electromagnetic radiation such as light, can escape

Question 24

what is an orbit

Answer 24

-the curved path of one celestial object or spacecraft around another celestial object

Question 25

what provides the force that allows planets and satellites to maintain their circular orbits?

Answer 25

-gravity is responsible for keeping planets and satellites in circular orbits

Question 26

does a planet in orbit around a star have a constant velocity?

Answer 26

-it has a constant speed but will not have a constant velocity because its direction will always be changing -(velocity is a measure of speed and direction, so if direction changes - velocity changes)

Question 27

what must happen to an orbiting object's speed if the radius of its orbit decreases?

Answer 27

-the orbital speed must increase for it to maintain a stable orbit

Question 28

are objects in orbit accelerating?

Answer 28

-yes as their direction is constantly changing, which means their velocity is changing.