P8.3 Beyond Earth

Question 1

What is red-shift?

Answer 1

When a light source moves away from you, the wavelength of the light it emits increases and the frequency decreases. This is called red-shift

Question 2

What is blue-shift?

Answer 2

When a light source moves towards you, the wavelength of the light it emits decreases and the frequency increases. This is called blue-shift

Question 3

What increases the magnitude of the shift?

Answer 3

If the source is moving faster, the shift is bigger

Question 4

What is the Big Band model?

Answer 4

The movement of galaxies proves that the universe is expanding. This came from something extremely dense and smaller than an atom which expanded suddenly 13.7 billion years ago.

Question 5

What evidence is there for the Big Bang model?

Answer 5

In 1960s, two scientists discovered microwave radiation coming from all directions. This was radiation left from the Big Bang called cosmic background radiation (CMBR).

Question 6

What is in our solar system?

Answer 6

The Sun
8 Planets
Moons
Minor Planets
Comets
Asteroid Belt

Question 7

How was the Sun formed?

Answer 7

The sun was formed from a huge cloud of dust and hydrogen gas. Gravity pulled the gas and dust together and as that happened the central core got very hot. Eventually, this caused nuclear fusion to start. There is balance between gravitational attraction and the expansion of hot gases outwards

Question 8

What is the state of our sun currently?

Answer 8

Stars like our sun are in an equilibrium state and are called main sequence stars. This is part of a star’s lifecycle.

Question 9

How does a star form a white dwarf?

Answer 9

A less massive star, such as our Sun, eventually becomes a white dwarf as the hydrogen is used up fusion slows down, and the core cools down.

Question 10

How does a red giant form?

Answer 10

Gravity pulls the outer layers inwards, the core heats up, and the star expands to form a red giant

Question 11

What materials form the Sun and where from?

Answer 11

The gas and dust that formed our Sun comes from other stars that have reached the end of their cycle

Question 12

What are natural satellites?

Answer 12

The moons around planets in the Solar System are natural satellites. These are made of the same materials as the rest of the solar system.

Question 13

What are artificial satellites?

Answer 13

Scientists have sent artificial satellites to orbit the planets. Our planet has thousands of artificial satellites in orbit around it.

Question 14

What are the two satellites orbiting Earth?

Answer 14

Geostationary Orbit
Low Polar Orbit

Question 15

What are the properties of geostationary orbit?
Time, Height, Position, Uses?

Answer 15

24 hours
36000km
Remains in fixed position above Earth’s equator
Communications, Satellite Television

Question 16

What are the properties of low polar orbit?
Time, Height, Position, Uses?

Answer 16

2 hours
2000km
Orbits over the poles
Military, Observation, Weather

Question 17

Why do orbits have a constantly changing velocity?

Answer 17

Gravity acts on a ball towards the centre of the planet. This is at right angles to the velocity. The force changes the direction so it is always accelerating but does not change the speed.

Question 18

What happens if an orbiting object speeds up or slows down?

Answer 18

Planets are in stable orbit which means they are moving at the right speed for the distance that they are from the Sun. If the satellite sped up, it would fly off. If it slowed down it would accelerate towards the Sun

Question 19

What does the radiation that an object emits depend on?

Answer 19

The type of radiation that an object emits depends on its temperature.
Hotter objects emit more radiation or a higher frequency whereas colder object emit less radiation of a low frequency

Question 20

What does the temperature of an object depend on?

Answer 20

If an object emits less radiation than it absorbs, the temperature increases. If an object emits more radiation that it absorbs, the temperature decreases

Question 21

What is the greenhouse effect?

Answer 21

Radiation from the Sun which is mostly UV passed through. It is absorbed by the Earth and is heated up. Some is re-emitted as IR. Some of it is absorbed by greenhouse gases and little IR is then radiated towards the earth.

Question 22

What is the inside of the Earth?

Answer 22

The centre of the earth has a solid inner core and an outer core which is liquid. The mantle above is almost entirely solid but it can flow. The crust is the upper layer and is solid

Question 23

What type of waves do earthquakes produce?

Answer 23

Seismic Waves

P waves, primary waves
S waves, secondary waves

Question 24

What is the difference between P-waves and S-waves?

Answer 24

P-waves are longitudinal waves so they can travel through solids and liquids
S-waves are transverse waves and cannot travel through liquids

Question 25

How do you measure earthquakes?

Answer 25

Seismometers are used near the earthquake centre. Sometimes earthquakes cannot be detected and this is because the Earth’s core is liquid.