⭐️topic SP7 - Astronomy

Question 1

What is the geocentric model?

Answer 1

The idea that the sun and all the planets are orbiting the Earth; the earth is the Center of everything

Question 2

Who came up with the geocentric model?

Answer 2

The greeek astronomer ptolemy

Question 3

What is the heliocentric model?

Answer 3

The idea that the sun is in the centre of the solar system

Question 4

Who came up with the heliocentric model?

Answer 4

The polish astronomer nicolaus Copernicus

Question 5

What did the invention of the telescope allow?

Answer 5

Scientists to see objects in space in much more detail and to find new objects

Question 6

What did Galileo Galilei achieve?

Answer 6

The discovery of four of Jupiter’s moons and by plotting their movements he proved not everything orbited the earth and lead him to support coppernicus’s idea

Question 7

What other discoveries were made with the improvements of telescopes?

Answer 7

Uranus, Neptune, the dwarf planet Pluto, asteroids and many comets

Question 8

What is the difference between a comet and an asteroid?

Answer 8

Comets are mostly made of ice, asteroids are rocky bodies

Question 9

What shape do all the planets move around the sun?

Answer 9

In an elliptical orbit

Question 10

What are natural satellites?

Answer 10

Moons

Question 11

What has the invention of photography allowed astronomers to do?

Answer 11

Make detailed observations and measurements.

Question 12

How have computers affected modern astronomy?

Answer 12

Increased the speed and detail in which info from telescopes can be analysed.

Question 13

Why are some telescopes in orbit around the earth?

Answer 13

• They give much clearer images as clouds and dust aren’t in the way.
• if the telescope is designed to detect radio waves and infrared emitted by space objects, they must be placed in orbit as the atmosphere absorbs some of that radiation

Question 14

What is weight?

Answer 14

Mass x gravitational field strength

Question 15

What is gravitational field strength in earth?

Answer 15

9.81N/kg

Question 16

What does gravitational field strength on a body depend on?

Answer 16

The mass of the body and the distance from its centre to the surface (radius)

Question 17

The greater the mass of a body…

Answer 17

…the smaller it’s radius and the greater it’s surface gravity

Question 18

What are artificial satellites used for?

Answer 18

Communication and to observe earth and space

Question 19

Describe satellites in highly elliptical orbits

Answer 19

The are used for communication in parts of the earth near the poles

Question 20

Describe a satellite in a polar orbit

Answer 20

Will eventually pass over all parts of the earth

Question 21

Describe satellites in circular geostationary orbits

Answer 21

They remain over 1 point on the Earth and are used for broadcasting. They move at 3070 m/s

Question 22

Describe satellites in low earth orbits

Answer 22

Need the least fuel for launching and they move around 7500 m/s

Question 23

Why does the force change its direction but not it’s speed on an orbiting body?

Answer 23

As the gravitational force between the earth and the satellite is at right angles to the direction of movement

Question 24

The gravitational force of a satellite in low orbit is…

Answer 24

…greater than that on a satellite in higher orbit

Question 25

There are two satellites. A is in a higher orbit than B, which one has to be moving faster to stay in orbit

Answer 25

B as if it slows down, it will fall towards the earth.

Question 26

What happens when an object falls out of orbit?

Answer 26

It gains speed as it falls until its moving fast enough to stay in a new lower orbit, if it falls into contact with the atmosphere, then the air will slow it down and it’ll eventually fall to earth

Question 27

How does a star start off?

Answer 27

A nebula - cloud of gas and dust

Question 28

If the hydrogen in a nebula has a large enough mass?

Answer 28

Gravity will cause it to pull into itself to form a ball being a protostar

Question 29

How is fusion triggered in starts?

Answer 29

When as the hydrogen atoms accelerate increasing kinetic energy and temperature allowing them to collide due to the increase in pressure

Question 30

What happens to a protostars once fusion is triggered?

Answer 30

It becomes a main sequence star upon entering the stable phase

Question 31

What forces are acting on a star?

Answer 31

Outward force of pressure from hot gases and the inward force of gravity causing the stars size to stay almost constant

Question 32

Why do bigger stars use up hydrogen faster?

Answer 32

As the pressure will be more immense and so the hydrogen atoms are more likely to collide causing fusion at a faster rate

Question 33

What happens after a star has ended its main sequence?

Answer 33

It becomes a red giant, the fuel has ran out and the Center collapses so all the matter begins to drift out

Question 34

What is left after a red giant?

Answer 34

A shell of gas which then gets pulled into form a white dwarf (still very hot and eventually a black dwarf

Question 35

What is the lifecycle of a star?

Answer 35

Nebula, protostar, main sequence star, red giant, white dwarf and black dwarf

Question 36

What is the sequence of a massive star?

Answer 36

Nebula, protostar, massive main sequence star, red super giant, super nova and then black hole or neutron star

Question 37

What happens after a super red giant collapse in a massive star?

Answer 37

A supernova explosion due to the huge mass when the Center collapse

Question 38

When does a super nova form a black hole?

Answer 38

If the cloud of gas left is 4x more than our star

Question 39

When does a supernova become a very dense neutron star?

Answer 39

If the cloud of gas left os 4x less than our star

Question 40

What is the definition of the Doppler effect?

Answer 40

The apparent change in the frequency or wavelength of a wave due to the relative motion of the source and the observer

Question 41

What is the difference in the frequency And wavelength of the sound waves from an ambulance siren between when approaching you and when heading away from you?

Answer 41

When approaching you, the frequency is longer and the wavelength is shorter but when moving away from you, the frequency is shorter and the wavelength is longer

Question 42

What does it mean if the visible spectrum of light from stars is red shifted?

Answer 42

The stars are moving away from us

Question 43

How do you know if a star is moving away faster or slower?

Answer 43

If moving away faster, then it’s more red shifted

Question 44

What is redshift?

Answer 44

A measure of how far along the spectrum the pattern of dark lines in the visible light spectrum have moved

Question 45

What does the spectrum look like if starts are moving towards us?

Answer 45

The pattern of lines moves towards the blue end of the spectrum as the wavelength of light becomes shorter and frequency increases

Question 46

What does red shift provide evidence for?

Answer 46

The universe expanding and the Big Bang theory

Question 47

The further away a galaxy us...

Answer 47

The greater it’s redshift and the faster it’s moving away from us

Question 48

How does red shift provide evidence for the Big Bang theory?

Answer 48

As the furthest galaxies away are moving faster so if time was reversed, galaxies further away would move back faster and closer galaxies would move back slower and would eventually all meet at one point.

Question 49

What does the Big Bang theory state?

Answer 49

The universe and all matter in it started as a tiny point of concentrated energy around 13.5 billion years ago

Question 50

What happened as the universe expanded?

Answer 50

Gravity caused matter to lump together and form stars

Question 51

What does the steady state theory suggest?

Answer 51

The universe has always existed and is expanding. New matter is continuously created within the universe as it expands

Question 52

Which theory says matter is being created all the time?

Answer 52

Steady state theory

Question 53

What does CMB stand for?

Answer 53

Cosmic background radiation

Question 54

What does the Big Bang theory says about radiation?

Answer 54

Huge amounts of it were released at the beginning of the universe.

Question 55

What is the radiation released by the Big Bang only detectable as now and why?

Answer 55

Microwave radiation as the wavelength of the radiation has increased

Question 56

How was CMB discovered?

Answer 56

By a radio telescope which detected microwave signals coming from all over the sky

Question 57

What does CMB provide supporting evidence for?

Answer 57

The Big Bang theory as it can’t be explained by the steady state theory.

Question 58

Which universe theory is accepted by more scientists today?

Answer 58

The Big Bang theory as it has more evidence

Question 59

How do some astronomers explain CMB?

Answer 59

Because the universe is still ‘cooling down’

Question 60

What’s significant about CMB in different directions?

Answer 60

the same amount is emitted in every direction - it’s uniform

Question 61

How can scientists measure the distance of a galaxy relative to earth?

Answer 61

By measuring the red shift