P16 Space Flashcards

1
Q

What are comets?

• What shape are their orbits?

A

Frozen rocks.

• Elliptical shape (ovalish)

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2
Q

What’s a meteor?

A

Small bits of rock that burn up when they enter the earth’s atmosphere. (Shooting star)

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3
Q

How did the sun form?

A

By clouds of dust and gas pulled together by gravitational attraction.

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4
Q

What temperature is the ‘habitable’ zone?

What does it mean?

A

1-100 degrees C

Liquid water can exist there.

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5
Q

What are stars formed from?

A

Gas and dust.

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6
Q

What is a protostar?

A

Is a concentration of gas and dust that becomes hot enough to cause nuclear fusion.

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7
Q

How does a protostar form?

A
  • Particles of dust and gas are pulled together by their own gravitational attraction - particles speed up.
  • Clouds merge
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8
Q

How does a star form?

A
  • Protostar
  • As it becomes denser the particles speed up more and the temp increases - energy transfer from GP energy to thermal.
  • If becomes hot enough, nuclei of the hydrogen atoms fuse together forming helium nuclei. Energy released.
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9
Q

Why is the sun stable?

A

Because the gravitational forces acting inwards balance the force of nuclear fusion in the core acting outwards.

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10
Q

Why is energy released inside a star?

A

Because of nuclear fusion.

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11
Q

When does a star become unstable? (Stats smaller then the sun or the same size)

What is the star now called?

A

It runs out of hydrogen nuclei. Reaches the end of its main-sequence stage it’s core collapses and it starts to swell.

A red giant.

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12
Q

How are heavier elements formed? (Nuclei larger than iron nuclei)

A

In the core of a red giant, helium and other light elements fuse.

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13
Q

What happens to stars much bigger than the sun after they finish their main-sequence stage?

A
  • They swell out and become red supergiants.
  • They collapse
  • in collapse, the matter surrounding the stars core compresses the core more and more, the compression suddenly reversed in a supernova
  • the explosion compresses the core into a neutron star.
  • If enough mass it turns into a black hole.
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14
Q

Stages of a star the same size or smaller then the sun?

A

Protostar ~ main-sequence star ~ red giant ~ white dwarf ~ black dwarf

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15
Q

Stages of a star much more massive than the sun?

A

Protostar ~ main-sequence star ~ red supergiant ~ supernova ~ neutron star (or black hole if enough mass)

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16
Q

An example of a:

  • Natural satellite
  • Artificial satellite
A
  • the moon

- a satellite

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17
Q

What shape is the earth’s orbit?

A

Circular.

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18
Q

What keeps a planet moving along its orbit?

A

The force of gravity between a planet and the sun

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19
Q

What keeps a satellite moving along its orbit?

A

The force of gravity between a satellite and the earth.

20
Q

As a body in a circular orbit moves around its orbit…?

3 points

A
  • The magnitude of velocity DOES NOT change. (Speed)
  • The direction of its velocity DOES change
  • It experiences an acceleration towards the centre of the circle
21
Q

What is the red-shift?

A

Is the shift to longer wavelengths (lower frequencies) of the light from the galaxy because it is moving away.

22
Q

The faster the galaxy is moving away…

A

The greater it’s red-shift

23
Q

What is a galaxy?

A

A enormous collection of stars that stay together because of the force of gravity between them.

24
Q

The universe is…

A

expanding.

25
Q

Evidence for the Big Bang?

A

Cosmic microwave background radiation (CMBR) can only be explained by the Big Bang. Red-shift

26
Q

What is the Big Bang theory?

A

That the universe began with a sudden unexplained explosion, and space, matter and time were created by it.

27
Q

Name given to the change in pitch of the sound of moving objects?

A

the Doppler effect

28
Q

Galaxy moving towards the Earth = …… shift

A

blue

29
Q

When does star finish main sequence phase?

A

when it runs out of fuel (hydrogen nuclei)

30
Q

Why cant heavier elements such as zinc form in sun’s core?

A

not hot or dense enough - too much energy required

31
Q

D. Black hole?

A

an area in space where the gravitational force is so great that not even light can escape it

32
Q

D. Light year?

A

the distance that light from an object can travel in one Earth year

33
Q

Force of gravity on a planet from the sun is an example of what force?

A

centripetal (acts towards the centre of a circle)

34
Q

Direction of motion of any planet in a circular orbit is….

A

at right angles to the direction of the force of gravity onit

35
Q

Why does a planet in a circular orbit experience acceleration towards the centre of a circle?

A

because the resultant force on it acts towards the centre of the circle

36
Q

Satellites too close to the Earth….

A

gradually loose speed due to atmospheric drag and gradually spiral downwards until hits the Earths surface

37
Q

Stable orbit?

A

moves around the Earths surface at a constant height

38
Q

Why does velocity of a planet on a circular orbit change but its speed doesn’t?

A

force is at 90 degrees to direction of motion so no work is done by the force so kinetic energy and speed don’t change

39
Q

Further a satellite is from the Earth or a planet….(2)

A
  • less particular speed is needed for it to remain in a circular orbit - force of gravity is weaker so doesn’t need to travel as fast
  • longer the orbiting body takes to move around orbit once
40
Q

D. Geostationary?

A

orbit where the object remains above 1 point on the earths surface constantly

41
Q

Neutron star?

A

extremely dense object made of only neutrons

42
Q

Missing mass in the universe =

?

A

dark matter - cant be seen

presence means that average density of universe is much greater then if it wasn’t there

43
Q

If density of universe is less then a particular amount, it will…. forever

A

expand - Big yawn

44
Q

If density of universe is more then a particular amount, it will….

A

stop expanding and go in reverse - Big crunch

45
Q

Steady State theory?

A

galaxies being pushed apart caused by matter entering universe through white holes