Topic 16 - Space

Question 1

What is the Big Bang Theory?

Answer 1

The theory that the universe was created in an outburst of all of the matter and energy in out universe and that it has been expanding ever since.

Question 2

What is a black dwarf star?

Answer 2

A star that has faded out and gone cold.

Question 3

What is a black hole?

Answer 3

An object in space that has such a large amount of mass that nothing, even light, can escape from its gravitational field. Its centre is a singularity with infinite mass and density.

Question 4

What is centripetal force?

Answer 4

The resultant force towards the centre of a circle acting on an object moving in a circular path.

Question 5

What is cosmic microwave background radiation? (CMBR)

Answer 5

Electromagnetic radiation that has been travelling through space ever since it was emitted shortly after the Big Bang.

Question 6

What is dark matter?

Answer 6

Matter in the galaxy that we cannot observe and has mot been accounted for. Its presence has only been deduced.

Question 7

What is the main sequence of a star?

Answer 7

The life stage of a star during which it radiates energy due to fusion of hydrogen nuclei in its core.

Question 8

What is a neutron star?

Answer 8

The highly compressed core of a massive star that remains after a supernova.

Question 9

What is a protostar?

Answer 9

The concentration of dust clouds and gas in space that forms a star.

Question 10

What is a red giant?

Answer 10

A star that has expanded and cooled, resulting in it becoming red and far larger and cooler than previously

Question 11

What is a red supergiant?

Answer 11

A star much more massive than the Sun that will swell out after the main sequence stage to become a red supergiant before collapsing.

Question 12

What is red-shift?

Answer 12

The increase in wavelength of electromagnetic waves emitted by a star or galaxy due to its motion away from us. The faster the speed of the star or galaxy, the greater the red-shift.

Question 13

What is a supernova?

Answer 13

The explosion of a massive star after fusion in its core ceases and the matter surrounding its core collapses on to the core and rebounds.

Question 14

What is a white dwarf?

Answer 14

A star that has collapsed from the red giant stage to become much hotter and denser.

Question 15

What is a moon?

Answer 15

A natural satelitte.

Question 16

What is a star?

Answer 16

A fixed luminous point in the universe, which uses nuclear fusion as its power source.

Question 17

What is a nebula?

Answer 17

A large cloud of dust and gas occupying space between stars.

Question 18

What is a meteorite?

Answer 18

Asteroid that has landed on the surface of Earth.

Question 19

What is a meteor?

Answer 19

Asteroid in the atmosphere.

Question 20

What is an asteroid?

Answer 20

A clump of rocks in space.

Question 21

What is a comet?

Answer 21

A clump of ice.

Question 22

What is the order of planets from the sun?

Answer 22

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

Question 23

What are the first 4 planets from the sun classified as?

Answer 23

Rocky planets.

Question 24

What is between Mars and Jupiter?

Answer 24

The asteroid belt.

Question 25

What are Jupiter and Saturn classified as?

Answer 25

Gas giants

Question 26

What are Uranus and Neptune classified as?

Answer 26

Cold gas giants.

Question 27

What are planets?

Answer 27

A celestial body in orbit of a star.

Question 28

How is a protostar formed?

Answer 28

-Clouds of dust rock and gas exist in a nebula. Gas is drawn inwards by gravity. The collapsing cloud begins to rotate and flatten into a disc of gas and dust.

-The disc rotates faster pulling material inwards. The particles collide more often, the temperature in the centre and the hot dense core makes a protostar.

Question 29

How is a star formed from a protostar?

Answer 29

-When the protostar becomes hot enough, hydrogen nuclei begin fusing, producing the heavier helium element. The energy released causes it to shine.

Question 30

How did the planets form?

Answer 30

-The sun at the centre gave off heat, evaporating ice in the cloud and pushing away gas, leaving clumps of rock orbiting close to the sun.

-The clumps aren’t hot enough to become protostars but form planets or asteroids.

Question 31

How does the star enter the main sequence?

Answer 31

Radiation pressure pushing outwards from the fusion reaction becomes equal to the gravity pulling inwards, the forces are balanced and the star is stable.

Question 32

What is the Hertzsprung-Russell diagram?

Answer 32

A scatter plot of stars in the universe based on temperature, luminosity and magnitude.

Question 33

What happens to a star if it becomes a red giant?

Answer 33

The star cools and swells when becoming a red giant, this collapses into a very small, hot and dense celestial object called a white dwarf.

The core compresses to a very dense state containing only neutrons called a neutron star.

Question 34

What happens when a star becomes a red supergiant?

Answer 34

The star cools and swells to form a red supergiant, this collapses forming heavy elements then explodes in a supernova, the elements are scattered throughout the universe.

Question 35

What happens to a star in the end of its life if it is categorised as a massive star?

Answer 35

The gravity will be very strong when it condenses, so light cannot escape as it has become a black hole with a singularity of infinite mass and density at its centre.

Question 36

What is the life cycle of an average star?

Answer 36

Stellar Nebula –> Average Star –> Red Giant –> Planetary Nebula –> White Dwarf

Question 37

What is the life cycle for a massive star?

Answer 37

Stellar Nebula –> Massive Star –> Red Supergiant –> Supernova –> Neutron Star or Black Hole.

Question 38

What is instantaneous velocity?

Answer 38

Velocity at a specific time.

Question 39

What is a stable orbit?

Answer 39

An orbit around a celestial body that doesn’t change.

Question 40

What are the differences and similarities between natural and artificial satelittes?

Answer 40

Differences:
-Natural satelittes are not man made, artificial satelittes are.
Similarities:
They both orbit around objects of greater mass than themselves.

Question 41

Why is a satelitte orbitting around an object at constant velocity said to be constantly accelerating?

Answer 41

Since velocity is a vector, it has direction and magnitude so if you keep magnitude constant and change direction, it will accelerate.

Question 42

What is a geostationary satelitte?

Answer 42

A satelitte which orbits around the celestial body at the same speed over the same place throughout its orbit.

Question 43

What is a geosynchronous satelitte?

Answer 43

A satelitte that orbits a celestial body at the same speed with which it moves but not over the same place.

Question 44

What are Low Polar Orbit satelittes?

Answer 44

These satelittes are very close to Earth compared with Geostationary satelittes so images generated by them are much clearer and sharper. Small objects can be tracked and they are used for short term weather forecasting.

Question 45

What are geostationary satelittes used for?

Answer 45

-Observing a larger area of the Earth’s surface.
-Observing longer term weather patterns.
-TV and radio signals can be broadcast around Earth.

Question 46

What is the Doppler Effect?

Answer 46

The wavelength of waves changes when an object moves towards or away from you. When they come towards you they increase in frequency and decrease in wavelength and when they move away they do the opposite.

Question 47

How did Edwin Hubble theorise that the universe had and is expanding?

Answer 47

He looked through his telescope to find that distant galaxies had redshifted, so their distance from Earth must be increasing, therefore the universe is expanding.

Question 48

How did Edwin Hubble’s ideas support the Big Bang theory?

Answer 48

Since he indicated that the universe was expanding, if we reverse the clock it would indicate that it originated from a single point, which affirms the Big Bang Theory.

Question 49

What does the Big Bang Theory state?

Answer 49

The Universe is expanding after exploding from a very small and dense region.

Space, time and matter were created in the Big Bang.

Question 50

Apart from Hubble’s ideas, what was discovered in 1965 that affirmed the Big Bang Theory?

Answer 50

In 1965 scientists discovered lower energy microwaves radiated in all directions, called cosmic microwave background radiation. This can only be explained by the Big Bang.

Question 51

What are the three theories for how the universe will end?

Answer 51

Open Universe - endless expansion
Flat Universe - continued but slowing expansion
Closed Universe - The Big Crunch where it collapses into another Big Bang which repeats.

Question 52

What are gravity waves?

Answer 52

Waves of the intensity of gravity that are generated by accelerated masses of binary stars and other motions of gravitational masses and propagate from the source at lightspeed.

Question 53

What is Dark Energy?

Answer 53

Unexplained energy that we cannot observe.