sp7 astronomy (paper 1)

Question 1

definition of a planet

Answer 1

• a sphere of rock or gas orbiting a star
• that is strong enough to have a bigger gravitational field to pull smaller objects into it’s orbit
• (must be big enough as well)

Question 2

definition of a star

Answer 2

a large mass at the centre of a solar system (if other bodies are present) that produces heat and light

Question 3

definition of a satellite

Answer 3

a body that orbits a planet

Question 4

definition of a dwarf planet

Answer 4

• an object orbiting a star that is massive enough to be rounded by it’s own gravity
• but not strong enough to pull objects in
• not a satellite

Question 5

definition of an asteroid

Answer 5

• a rock in space made of metals and rocks in elliptical orbits
• can be found between mars/jupiter and in kuiper belt

Question 6

definition of a comet

Answer 6

• a ball of icy rock that follows an elliptical orbit around the sun
• begins to vaportise when close to the sun

Question 7

what does the gravitational field strength depend on

Answer 7

• mass of the body and distance
• greater mass and smaller radius = stronger

Question 8

define elliptical

Answer 8

a shape like a squished circle

Question 9

what are the stages in order for a smaller star

Answer 9

• nebula
• protostar
• main sequence star
• red giant star
• white dwarf
• black dwarf

Question 10

what are the stages in order for a larger star

Answer 10

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

Question 11

what does CMB radiation stand for

Answer 11

Cosmic Microwave Background radiation

Question 12

what are the two main theories for the creation of the universe

Answer 12

steady state and big bang

Question 13

what is the steady state theory

Answer 13

• the universe has always existed and is expanding
• matter is continously created within the universe as it expands

Question 14

what is the big bang theory

Answer 14

all matter started at a tiny concentrated point of energy that expanded from this point and is still expanding

Question 15

what theory does CMB support

Answer 15

big bang

Question 16

what theory does red-shift support

Answer 16

steady state and big bang

Question 17

explain the doppler effect

Answer 17

• the change of frequency and pitch in a moving object
• as it moves towards you, it has a higher fequency and higher pitch
• as it moves away, it has a lower frequency and lower pitch

Question 18

define geostationary

Answer 18

remains at the same point over the earth at all times

Question 19

describe the orbit of a comet

Answer 19

• highly elliptical
• speed of the comet is faster closer to the sun and slower further away
• when it melts, the gas shoots away from the sun

Question 20

what are satellites in geostationary orbits used for

Answer 20

broadcasting as they move at the same speed as the rotation of the earth (3070m/s)

Question 21

what are satellites in highly elliptical orbits used for

Answer 21

communications near the poles

Question 22

describe the how the speed of artificial satellites affects the orbit around the earth

Answer 22

• satellites need less fuel to launch but need a faster speed or it will fall towards the earth
• as it falls, it gains speed until it’s fast enough to stay in a new, lower orbit
• if it goes low enough to encounter the atmosphere, it will fall into the earth
• if a satellite goes faster, it will get further from the earth
• ig it goes too fast, it would’ve orbited it’s way out of the earths orbit

Question 23

what is a nebula

Answer 23

a cloud of gas and dust in outer space

Question 24

what is a protostar

Answer 24

when a nebula is massive enough to collapse under gravity, to form the early stage in the formation of stars

Question 25

what is a main sequence star

Answer 25

• when the star is in it’s stable stage
• nuclear fusion at the core
• fusing hydrogen nuclei to helium nuclei
• a balance between outward radiation and the force of gravity inwards occurs

Question 26

what is a red giant star

Answer 26

when all hyrdogen has been used to fusion, and larger nuclei form and the star may expand to a red giant

Question 27

what is a white dwarf

Answer 27

when a small star may contract under the pull of gravity to change colours as it cools

Question 28

what is a black dwarf

Answer 28

hypothetical star that no longer emits heats or light

Question 29

what is a red super giant star

Answer 29

an aging giant star that has consumed its core’s supply of hydrogen fuel

Question 30

what is a supernova

Answer 30

when a larger star with more mass will keep nuclear reactions, getting hotter and expanding until explodes, throwing hot gas into space

Question 31

what is a neutron star

Answer 31

made entirely from neutrons, compressed like a giant atomic structure

Question 32

what is a black hole

Answer 32

a body of large mass that is so dense that everything, including light, cannot escape

Question 33

why does CMB only support the big bang

Answer 33

• big bang states huge amounts of radiation were released
• bcs the universe is still expanding, the wavelength of this radiation has increased
• so now it’s only detectable as microwave radiation

Question 34

define geocentric

Answer 34

the earth is at the centre

Question 35

define heliocentric

Answer 35

the sun is at the centre

Question 36

what is meant by red-shift

Answer 36

the change in wavelength of light from a distant object as it moves away

Question 37

who discovered red-shift

Answer 37

edwin hubble

Question 38

what causes the wavelength of light from a moving object to change

Answer 38

• frequency, pitch, and wavelength
• lower frequency/pitch and higher wavelength means its moving further away faster

Question 39

what does it mean when an object is not red shifted at all

Answer 39

the object isn’t moving away from us

Question 40

what does it mean when an object is red shifted

Answer 40

the object is getting further away from us at an increasing speed