Space Physics Flashcards

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1
Q

What is the universe made up of?

A

billions of galaxies

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2
Q

What does each galaxy contain?

A

hundreds of millions of stars

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3
Q

What do we have within our solar system?

A
  • one star (the sun)
  • 8 planets and the dwarf planets that orbit the sun
  • asteroids and comets that also orbit the sun
  • moons that orbit planets (natural satellites)
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4
Q

Give a brief description to how the solar system was formed.

A

1) Sun formed from the nebula ( cloud of dust and gas) which was pulled together by gravitational attraction
2) as dust and gas were drawn together, they collided, increasing the temperature and creating a protostar
3) As more material were drawn together gravity, these collisions increased until the temperature was high enough for hydrogen nuclei to fuse together = helium and a main-sequence star is formed (nuclear fusion)
4) material not drawn into the sun remained in orbit around the sun and formed the planets and other objects in the solar system

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5
Q

How is the core of the Sun kept hot?

A

the energy released by nuclear fusion

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6
Q

What is the sun stability the result of?

A
  • the fusion energy trying to expand the sun

- gravity acting inwards trying to collapse the sun

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7
Q

The lifecycle of a star depends on what?

A

its size

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8
Q

what do small stars, large stars and larger stars become?

A

small stars = black dwarf stars

large stars = neutron stars

largest stars = black holes

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9
Q

What is the star cycle for a small star?

A

1) the hydrogen in the star begins to run out which means that the outward force due to fusion energy is less than the inward force due to gravity - this causes the star to collapse inwards
2) star expands to become a red giant
3) it then becomes unstable and ejects its outer layer of dust and gas. this leaves behind a hot dense solid core - a white dwarf
4) this will cool down, it emits less and less energy eventually becoming a cold black dwarf

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10
Q

What is the star cycle for a large star?

A

1) the hydrogen in the star begins to run out which means that the outward force due to fusion energy is less than the inward force due to gravity - this causes the star to collapse inwards
2) Sun expands to become a red supergiant. Helium fusion within this red supergiant allows for the production of nuclei as heavy as iron
3) Nuclear fusion is eventually no longer carried out by red supergiant. As the core of the red supergiant cools down, the pressure forcing it outwards will decrease and will no longer be strong enough to balance the inwards force of gravity.
4) this cause the star to shrink rapidly, which causes a huge increase in its core temperature and the star explodes in a supernova
5) this releases tremendous amounts of energy and scattering material of the star into space
6) the exploding supernova throws the out layers of dust and gas into space, leaving a very dense core - neutron star

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11
Q

What is the star cycle for a larger star?

A

1) the hydrogen in the star begins to run out which means that the outward force due to fusion energy is less than the inward force due to gravity - this causes the star to collapse inwards
2) Sun expands to become a red supergiant. Fusion of helium within this red supergiant allows for the production of nuclei as heavy as iron
3) Nuclear fusion is eventually no longer carried out by red supergiant. As the core of the red supergiant cools down, the pressure forcing it outwards will decrease and will no longer be strong enough to balance the inwards force of gravity.
4) this cause the star to shrink rapidly, which causes a huge increase in its core temperature and the star explodes in a supernova
5) this releases tremendous amounts of energy and scattering material of the star into space
6) if the star is massive enough, it will become a black hole

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12
Q

what is a black hole

A

a super dense point in the universe and has such a large gravity that even light can’t escape

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13
Q

What happens in a supernova?

what is formed?

A

starts are able to form elements heavier than iron and eject them into the universe to form new planets and stars

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14
Q

how do fusion processes lead to the formation of new elements?

  • include how the universe was before stars
A

before stars, the only element in the universe was hydrogen

fusion processes in stars created all of the elements in the periodic table

all stars fuse hydrogen into helium

bigger stars then fuse helium into lithium and other lightweight elements, up to and including iron

during a supernova, the amount of energy released is so great that the temperature and pressure is high enough to force nuclei together to create elements heavier than iron

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15
Q

what do planets orbit

How do planters and satellites maintain their circular orbits

A

the sun

through the gravitational force (centripetal force) between them and the sun

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16
Q

Examples of artificial satellites?

A

TV and GPS systems

17
Q

What does the force towards the centre of the circle result in?

A

an unbalanced force that results in acceleration towards the centre

18
Q

Describe the speed and velocity of objects orbiting

A

speed is constant

velocity changes constantly

19
Q

instantaneous velocity is ________ to the centripetal force

A

perpendicular

20
Q

How does the radius change when the speed changes?

A
  • if the speed increases, radius decreases, because at a higher speed the satellite needs a greater force of gravity to maintain a stable orbit (prevent it from flying off to space)
  • if the speed decreases = radius increases