topic 8 - space physics

Question 1

what is a satellite?

Answer 1

any object that orbits a celestial body, such as a star, planet or our moon.

Question 2

what are the shape ob the orbit of comets?

Answer 2

elliptical

Question 3

where is the asteroid belt found?

Answer 3

between mars and jupiter

Question 4

what are comets mostly made of?

Answer 4

ice and dust

Question 5

what are asteroids mostly made out of?

Answer 5

rock and metal

Question 6

what is a galaxy?

Answer 6

a collection of billions of stars

Question 7

what are stars in a galaxy held together by?

Answer 7

gravity

Question 8

what does most of the universe consist of?

Answer 8

empty space

Question 9

what is the order of size for things in the universe?

Answer 9

satellite, planet, solar system, galaxy, universe

Question 10

what is a nebula?

Answer 10

a large cloud of dust and gas

Question 11

what pulls the gas and dust in a nebula together to from a pro star?

Answer 11

the attraction of gravity

Question 12

as a pro star grows in size and attracts more particles from the surrounding nebula, what changes happen?

Answer 12

• nucleur fusion could initiate
• temp increases
• becomes more dense

Question 13

once nucleur fusion starts in a protostar, what does it become?

Answer 13

a main sequence star

Question 14

what happens with the direction of pressure when fusion happens in a protostar?

Answer 14

energy released creates an outward pressure that balances against the inward pressure from gravity

Question 15

what stage of a star’s life cycle is the sun currently in?

Answer 15

main sequence star

Question 16

after the main sequence, what could a star become?

Answer 16

a red giant or a red super giant

Question 17

what is a nebula?

Answer 17

a cloud of dust and gas

Question 18

what is a protostar?

Answer 18

when the force of gravity pulls a nebular together

Question 19

how does a protostar become bigger? and what then happens?

Answer 19

it’s gravity pulls more gas and dust into it, meaning it gets bigger and the gravity gets stronger
- it also pulls itself together squeezing it making it more dense
- meaning the particles are colliding together more often and it raises the temperature
- when the pressure becomes large enough, the hydrogen nuclei start to bond to form helium nuclei in the nucleur fusion process
- giving large amounts of energy, keeping the inside of the star hot - now a main sequence star.

Question 20

what stage is the sun in at the moment and what is it?

Answer 20

• main sequence star period
• the outward pressure of nucleur fusion is equal to the inward pressure of gravity
• this is a long stable period that lasts for billions of years
• at some point it will start to run out of hydrogen, meaning it will not be able to do anymore nucleur fusion, the gravity inward pressure takes over meaning the star now becomes smaller.
• this happens until it is so hot and dense nucleur fusion starts up again, causing it to expand again
• the nucleur fusion now forms heavier elements

Question 21

after a main sequence star what comes next and what does it depend on?

Answer 21

• if the star was small to medium then it would become a red giant
• if it was really big, it would become a red super giant

Question 22

what is the process of a red giant?

Answer 22

• it becomes unstable and expels its outer layers
• leaving behind a hot, dense, solid core called a white dwarf (this does nucleur fusion)
• this gives off loads of light and it relatively small.
• over time it gets cooler and darker as it emits all of its energy
• then transitions to a black dwarf, because it no longer has enough energy to emit light

Question 23

what is the process of a red super giant?

Answer 23

• shine more brightly as they undergo more nuclear fusion
• undergo several cycles or expansion and contraction
• eventually explode into a supernova, forming elements even heavier than iron that get ejected all across the universe
• if the star was very big, it then condenses into a neutron star that has a dense core
• if the star was absolutely massive, it may collapse in on itself and become a black hole.
• the gravity is able to pull in any light that passes nearby

Question 24

what is an overview of the life cycle of stars?

Answer 24

• dust and gas is pulled together by gravity
• a protostar is formed
• main sequence star is formed
• if the star was small to medium, it forms into a red giant, then a white dwarf, then a black dwarf,
• if the star was big, it explodes into a supernova, then if it was just big it condenses into a neutron star, but if it was really massive it becomes a black hole.

Question 25

what elements do nuclear fusion form at each stage of a stars life cycle?

Answer 25

main sequence star = fuses hydrogen to make helium
red super giants = forms heavier elements up to iron on the periodic table
supernovas = create elements heavier than iron

Question 26

what is an orbit?

Answer 26

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

Question 27

what happens to an objects speed and velocity when in orbit?

Answer 27

the speed is constant, but the velocity is changing

Question 28

if an object moves closer to the objects its orbiting, what is required for the object to stay in orbit?

Answer 28

the magnitude of the velocity must increase

Question 29

what does redshift show us about about where other galaxies are?

Answer 29

• that they are moving away from us (the space in between us is expanding)

Question 30

what are some limitations of models of the expansion of the universe?

Answer 30

• balloon for example bursts, the universe isn’t likely to burst
• galaxies should be represented in the balloon.

Question 31

what is cosmic microwave background radiation?

Answer 31

electromagnetic radiation that is observed in all directions
initially, the radiation from the big bang was incredibly hot
as the universe has expanded and cooled, the background radiation has dropped in frequency

Question 32

what side of the absorption spectra has the longer wavelength?

Answer 32

red side on the left

Question 33

how do some wavelengths of light appear to be missing?

Answer 33

• a star emits light of all wavelengths
• some wavelengths of light are absorbed by chemicals in the stars atmosphere

Question 34

what provides evidence for the big bang?

Answer 34

red-shift

Question 35

how many galaxies show red shift?

Answer 35

nearly all

Question 36

why does red shift occur?

Answer 36

because the light emitted by an object moving away from the earth will be stretched
this stretching causes the lights wavelength to increase
the faster an object moves away from us, the larger the red shifts

Question 37

what is the basic idea of the big bang theory?

Answer 37

that the universe expanded from a single tiny point of high density and pressure

Question 38

why do we believe in the big bang theory?
(6 points)

Answer 38

1. light that reaches earth from other galaxies shows redshift, the further away the galaxy the more the redshifted its light is
2. suggesting all galaxies are moving away from us, and moving away from each other
3. suggesting that the whole universe is expanding
4. if we extrapolate further and further back in time, it implies that the universe must have been smaller in the past
5. ultimately, it’s believed the universe started from a single point which had all of the mass and energy of the universe contained in that point
6. the expansion of the universe front his initial small point is called the big bang theory that started around 13.8 billion years ago.