Topic 8 - Space Physics (1)

Question 1

STAR LIFE CYCLE:
1) What do stars initially form from?

Answer 1

they form from a cloud of dust and gas called a nebula

Question 2

STAR LIFE CYCLE:
2) What happens to the nebula?

Answer 2

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

Question 3

STAR LIFE CYCLE:
2) What happens to the protostar as temperature rises?

Answer 3

• the star gets denser and more particles collide with each other
• when the temperature gets high enough, hydrogen nuclei undergo nuclear fusion to form helium nuclei
• this gives out huge amounts of energy, which keeps the core of the star hot
• a star is formed

Question 4

STAR LIFE CYCLE:
3) When does a star become a main sequence star?
What happens during this time?

Answer 4

• after the star is a protostar
• the star enters a long stable period where outward pressure caused by nuclear fusion that tries to expand the star balances the force of gravity pulling everything inwards
• this typically lasts several billion years

Question 5

STAR LIFE CYCLE:
4) What two things happen when the hydrogen runs out?
What happens during this stage?

Answer 5

• the star swells into a red giant (if its a small star) OR a red super giant (if its a larger star)
• fusion of helium (and other elements) occurs.
• heavier elements (up to iron) are created in the core of the star

Question 6

STAR LIFE CYCLE:
4) Why do stars become red when the helium runs out?

Answer 6

the surface cools

Question 7

STAR LIFE CYCLE:
5) How does a white dwarf form?

Answer 7

a small-to-medium sized star (like the sun) then becomes unstable and ejects its outer layer of dust and gas
this leaves behind a hot, dense solid core (a white dwarf)

Question 8

STAR LIFE CYCLE:
6) What happens to a white dwarf as it cools down?

Answer 8

it emits less and less energy
when it no longer emits a significant amount, its called a black dwarf

Question 9

STAR LIFE CYCLE:
7) Instead, what happens to large stars after being a red super giant?

Answer 9

• they begin to glow brightly again as they undergo more fusion and expand and contract several times, forming elements as heavy as iron under various nuclear reactions
• eventually they’ll explode into a supernova forming elements heavier than iron and ejecting them into the universe to form new planets and stars

Question 10

STAR LIFE CYCLE:
REMEMBER: stars and their life cycles produce and distribute all naturally occuring elements

Question 11

STAR LIFE CYCLE:
8) Finally, what happens to the exploding supernova?

Answer 11

It throws out layers of dust and gas into space, leaving a very dense core called a NEUTRON STAR.
If the star is massive enough, it will become a black hole

Question 12

STAR LIFE CYCLE:
What is a black hole?

Answer 12

a super dense point in space that not even light can escape from

Question 13

THE SOLAR SYSTEM AND ORBITS:
What is the solar system?

Answer 13

all the stuff that orbits our sun

Question 14

THE SOLAR SYSTEM AND ORBITS:
What are planets?

Answer 14

• these are large objects that orbit a star
• they have to be large enough to have “cleared their neighbourhoods” - this means that their gravity is stong enough to have pulled in a nearby objects apart from their natural satellites

Question 15

THE SOLAR SYSTEM AND ORBITS:
How many planets are in our solar system?
What are they called?

Answer 15

• there are 8 in our solar system
• mercury, venus, earth, mars, jupiter,
  saturn, uranus, neptune

Question 16

THE SOLAR SYSTEM AND ORBITS:
What are dwarf planets?
Give an example?

Answer 16

planet-like objects that orbit stars but they don’t meet all the criteria for being a planet
for example, pluto

Question 17

THE SOLAR SYSTEM AND ORBITS:
What are moons?

Answer 17

a type of natural satellite (not man made) that orbit planets

Question 18

THE SOLAR SYSTEM AND ORBITS:
What are artificial satellites?

Answer 18

satellites humans have built, they generally orbit the earth

Question 19

THE SOLAR SYSTEM AND ORBITS:
What galaxy is our solar system a part of?

Answer 19

the Milky Way galaxy

Question 20

THE SOLAR SYSTEM AND ORBITS:
What is the milky way galaxy?

Answer 20

a massive collection of billions of stars held together by gravity

Question 21

THE SOLAR SYSTEM AND ORBITS:
What provides the force that creates orbits?

Answer 21

gravity

Question 22

THE SOLAR SYSTEM AND ORBITS:
What do planets orbit?

Answer 22

the sun in almost circular orbits

Question 23

THE SOLAR SYSTEM AND ORBITS:
What does it mean if an objects is travelling in a circle?

Answer 23

• it is constantly changing direction
• which means it is constantly accelerating
• this also means the velocity is constantly changing (but not the speed)

Question 24

THE SOLAR SYSTEM AND ORBITS:
What is a satellite?

Answer 24

an object that orbits a second, more massive object

Question 24

THE SOLAR SYSTEM AND ORBITS: What does the size of an orbit depend on?

Answer 24

the object's speed

Question 25

THE SOLAR SYSTEM AND ORBITS: What happens as you get closer to a star or planet?

Answer 25

the gravitational force gets stronger

Question 26

THE SOLAR SYSTEM AND ORBITS: How does a stronger gravitational force affect the object trying to orbit the planat or star?

Answer 26

the orbiting object needs to travel faster in order to remain in orbit (to not crash into the object that it's orbiting)

Question 27

THE SOLAR SYSTEM AND ORBITS: What needs to happen for an object to remain in a stable orbit?

Answer 27

if the speed of the objects changes, the size (radius) of its orbit must do so too

Question 28

THE SOLAR SYSTEM AND ORBITS: How does the orbit of faster moving objects compare to slower moving objects?

Answer 28

faster moving objects will move in a stable orbit with a smaller radius than slower moving ones