Topic 7

Question 1

What does our solar system consist of

Answer 1

Sun, eight planets and their natural satellites, dwarf planets, asteroids and comets

Question 2

Recall names of planets in our solar system

Answer 2

Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune

Question 3

Describe geocentric model

Answer 3

Theory suggests sun, moon, planets and stars all orbited earth in perfect circles. Accepted from time of ancient Greeks until 1500s

Question 4

Describe the heliocentric model

Answer 4

Earth and all planets orbit sun in perfect circles

Question 5

Describe the orbits of moons, planets, comets and artificial satellites

Answer 5

Planets- large objects orbiting a star in an ellipse
Moons- orbit planets with almost circular orbits
Comets- highly elliptical orbits, travel from near to sun to outskirts of solar system
Artificial satellites- orbit earth in fairly circular orbits

Question 6

in a stable orbit what happens if the speed of the object changes?

Answer 6

the radius must change, faster moving objects will move in a stable orbit with a smaller radius than slower moving ones.

Question 7

Describe the Steady State theory.

Answer 7

• says universe has always existed as it is now, and it always will.
• as universe expands, new matter is constantly being created
• means density of earth always roughly the same
• no beginning or end to universe

Question 8

Describe The Big Bang theory

Answer 8

• initially all matter in universe occupied very small space
• tiny space was very dense, so very hot
• then it ‘exploded’, space started expanding, and expansion still going on
• theory gives a finite age for universe

Question 9

Describe red-shift to evidence the big bang theory

Answer 9

• there’s an observed increase in the wavelength of light coming from galaxies and patterns have been shifted towards red end of spectrum,red-shift. measurements of red-shift suggest all distant galaxies are moving away from us quickly.
• more distant galaxies have greater red-shifts than nearer ones, means more distant galaxies moving away faster than nearer ones. provides evidence that whole universe expanding

Question 10

Describe cosmic microwave background to evidence the big bang theory

Answer 10

• scientists have detected low frequency electromagnetic radiation (mainly microwaves)coming from all parts of universe
• only supports big bang theory
• shows universe had a beginning

Question 11

how do both the big bang and steady state theories both account for red-shift of galaxied

Answer 11

in both models, objects are moving away from the observer as the universe expands

Question 12

how did the discovery of CMB radiation lead to the big bang theory becoming the currently accepted model

Answer 12

-according to big bang model CMB radiation is is leftover energy of initial explosion

Question 13

state the order of a stars life cycle of a mass similar to the sun

Answer 13

nebula, protostar, main sequence star, red giant, white dwarf

Question 14

state the order of a stars life cycle of a mass larger than the sun

Answer 14

nebula, protostar, main sequence star, red supergiant, supernova, neutron star or black hole

Question 15

Nebula (1)

Answer 15

stars initially form from cloud of dust and gas called a nebula

Question 16

Protostar (2)

Answer 16

force of gravity pulls dust and gas together to form protostar. the temperature rises as star gets denser and more particles collide. when temp gets high enogh, hydrogen nuclei undergo nuclear fusion to form helium nuclei, gives out huge amounts of energy, keeps star core hot. a star is born

Question 17

Main sequence star (3)

Answer 17

star enters long stable period, outward pressure caused by thermal expansion balances force of gravity pulling everything inwards. in stable period called main sequence star heavier star=shorter time on main sequence

Question 18

Red giant / Red supergiant (4)

Answer 18

eventually hydrogen in core begins to run out and force due to gravity is larger than the pressure of thermal expansion. star compressed, until dense and hot enough that the energy created makes the outer layers of star expand. star becomes red giant (if small star) or red supergiant (if larger star) .

Question 19

White dwarf (5)

Answer 19

small-to-medium star like the sun becomes unstable and ejects its outer layer of dust and gas, leaving a hot, dense solid core-white dwarf

Question 20

Supernova (6)

Answer 20

big stars, however, start to glow brightly again as they undergo more fusion to make heavier elements. they expand and contract several times , as balance shifts between gravity and thermal expansion. eventually they explode in a supernova

Question 21

Neutron star/ Black hole (7)

Answer 21

exploding supernova throws the outer layers of dust and gas into space, leaving very dense core called neutron star. If star massive enough, it’ll collapse and become black hole

Question 22

why are some telescopes located outside the Earth’s atmosphere

Answer 22

• no light pollution
• no adverse weather conditions
• no atmosphere to reduce resolution

Question 23

x-ray telescopes

Answer 23

good way to ‘see’ violent, high temperature events in space

Question 24

radio telescopes

Answer 24

were responsible for discover of CMB radiation

Question 25

how have telescopes changed?

Answer 25

• earliest telescopes all optical telescopes
• from 1940s onwards, telescopes were developed for all parts of EM spectrum
• bigger telescopes give better resolution + gather more light, so can look at faint objects
• improved magnification, so can look further into space
• now telescopes used alongside computers,computers create clearer, sharper images and make it easy to capture images

Question 26

what happens if a wave source is moving relative to an observer

Answer 26

there will be a change in the observed frequency and wavelength