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LTS GCSE Physics Separate H > 8 Space > Flashcards

8 Space Flashcards

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1
Q

What is a light-year?

A

A unit of distance for astronomical scales. The distance light can travel in one earth year.

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2
Q

How many stars are in our solar system?

A

One - the sun

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3
Q

Name the planets in our Solar System in order of distance from the sun.

A

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

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4
Q

What is a planet?

A

A non-luminous, spherical object that orbits a star. It must dominate its orbit.

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5
Q

What is a moon?

A

A non-luminous, natural object that orbits a planet.

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6
Q

What is a galaxy?

A

A large collection of dust, gas and stars (each a possible planetary system of its own) held together by gravity.

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7
Q

What type of object is Pluto?

A

Dwarf planet

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8
Q

What is a ‘dwarf planet’?

A

A planet-like object in space that orbits a star but doesn’t match all the rules of being a planet

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9
Q

What is the name of our galaxy?

A

Milky Way

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10
Q

What is found in the spaces between astronomical objects (such as planets, moons, asteroids)?

A

There is a small amount of dust but there?s no air (we think of it as a vacuum), so sound can?t travel, but there is still gravity due to all of the masses nearby.

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11
Q

How was the Sun formed?

A

From clouds of dust and gas drawn together by gravity, which caused fusion reactions to occur.

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12
Q

What is a nebula?

A

A cloud of dust and gas in space

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13
Q

What is a protostar?

A

The earliest stage in the life cycle of a star. Formed when the force of gravity causes a nebula to collapse. The increased temperature and pressure allows fusion to begin.

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14
Q

What is a main sequence star?

A

A star during the main part of its lifecycle. The radiation pressure outwards from nuclear fusion balances the force of gravity inwards.

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15
Q

What is a red giant?

A

A star, about the same size as our sun, that has expanded and cooled. It has used up all the hydrogen in its core and is now fusing helium

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16
Q

What is a red supergiant?

A

A star, much larger than our sun, that has expanded and cooled. It has used up all the hydrogen in its core and is now fusing helium

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17
Q

What is a white dwarf?

A

The hot, dense solid core of a red giant once it has ejected its outer layer as a planetary nebula.

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18
Q

What is a black dwarf?

A

A white dwarf that has cooled sufficiently that it no longer emits significant heat or light.

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19
Q

What is a supernova?

A

An explosion produced when the core of a red supergiant collapses. Elements heavier than iron are formed and ejected into space.

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20
Q

What is a neutron star?

A

The core of a red supergiant that has collapsed but can still be seen

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21
Q

What is a black hole ?

A

The core of a red supergiant that has collapsed. These are formed if the remaining core has a mass of more than 3 times the mass of the Sun. It is so dense that light can not escape it.

22
Q

When the temperature within a protostar gets high enough, what process can begin?

A

Nuclear fusion (of Hydrogen into Helium)

23
Q

What force brings the dust and gas inside a nebula together to form a star?

A

Gravitational force

24
Q

Describe what happens to stars the size of the sun or smaller after the main cycle

A

Hydrogen runs out, Hydrogen fusion stops, Helium nuclei fuse to form larger nuclei (up to iron), star expands to be become red giant, eventually outer layers drift away leaving a white dwarf, then black dwarf

25
Q

Describe what happens to stars much larger the sun after the main cycle

A

Hydrogen runs out, Hydrogen fusion stops, Helium nuclei fuse to form larger nuclei (up to iron), star expands to be become red giant, star collapses and explodes in supernova, forming heavier elements, leaving behind neutron star or black hole

26
Q

Why are main sequence stars in a state of equilibrium?

A

The force of gravity pulling the material inwards is balanced by an outwards force due radiation pressure (due to nuclear fusion).

27
Q

What is nuclear fusion?

A

When two small nuclei fuse together to form one larger nucleus, releasing energy in the reaction.

28
Q

How does nuclear fusion relate to stars?

A

The energy released by fusion reactions leads to the light that we see from stars. It causes an outward force that would cause the star to expand if it weren’t in equilibrium with the force of the gravitational collapse.

29
Q

Which elements are produced in fusion in stars?

A

All naturally occurring elements, up to iron.

30
Q

Where are elements heavier than this produced?

A

In a supernova

31
Q

How are they distributed across the universe?

A

In the supernova explosion

32
Q

How do scientists know that our solar system is a second generation system ?

A

It contains heavy elements (such as gold, lead etc) which could only have been formed in a supernova and were then distributed throughout space by the explosion.

33
Q

What is the force that keeps planets and satellites in orbit?

A

Gravitational force

34
Q

What is an orbit?

A

The elliptical path that one object in space takes around another object. It is caused by the gravitational attraction between the two objects.

35
Q

What shape are the orbits of the planets?

A

Elliptical

36
Q

Name a natural satellite of the Earth.

A

The moon.

37
Q

What is an artificial satellite?

A

An object put into orbit around an astronomical object by humans e.g. the international space station around Earth, or the Pioneer probes around the Sun.

38
Q

In a circular orbit, how can there be changing velocity if the speed is constant?

A

As it is attracted by gravity, it is constantly changing direction to remain in the circular orbit. Velocity is a vector quantity.

39
Q

What quantity is defined as the rate of change of velocity?

A

Acceleration

40
Q

What is the name given to the resultant force that keeps objects moving in circles?

A

Centripetal force

41
Q

In what direction does a centripetal force act?

A

Towards the centre of the circle

42
Q

For a stable orbit, if the radius of the orbit decreases, what must happen to the speed?

A

The speed must increase.

43
Q

What factors affect the orbital speed of a satellite?

A

The mass of the planet or star, the mass of the satellite and the distance between the satellite and the object it is orbiting

44
Q

What is the Doppler Effect?

A

The observed frequency of waves emitted by a moving object appear changed.

45
Q

What is red-shift in observation of galaxies?

A

There is an observed increase in the wavelength of light from most distant galaxies. The further away the galaxies, the faster they are moving and the bigger the observed increase in wavelength.

46
Q

What is the Big Bang theory?

A

It suggests that the universe began from a very small region that was extremely hot and dense.

47
Q

How does observed red shift support the Big Bang theory?

A

It shows that the universe is expanding, so therefore must have once been much smaller.

48
Q

Since 1998 onwards, observations of supernovae suggest that?

A

The furthest away galaxies are moving away from us even faster.

49
Q

Explain what this image shows if the middle spectrum is from our Sun.

A

The top spectrum shows the absorption pattern (black lines) shifted towards the shorter, blue wavelengths of light - so this star must be moving towards us as the light is being compressed. The bottom spectrum shows the pattern shifted towards the longer, red wavelengths - so this star must be moving away from us as light is being stretched.

50
Q

Why is it important for scientists to observe?

A

Observations allow them to obtain data, which they use to arrive at theories like the Big Bang theory.

51
Q

There is still lots that scientists don’t understand about the universe such as dark matter and dark energy. What are they an explanation for?

A

The expansion of the universe is slower than scientists would expect, so there must be something holding the universe together. We think about 68% of the universe is dark energy, 27% is dark matter and the rest is our known universe. We call them dark because we don’t know much about them but believe that they must exist to make sense of observations.

LTS GCSE Physics Separate H (1 decks)

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