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Space physics Flashcards

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1
Q

What is a mnemonic to remember the order of the planets in the solar system?

A

My - Mercury
Very - Venus
Enthusiastic - Earth
Mother - Mars
Just - Jupiter
Served - Saturn
Us - Uranus
Nine - Neptune
Pizzas - Pluto

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2
Q

What is within our solar system?

A

one star (the Sun), eight planets, the dwarf planets (including Pluto), and natural satellites (moons that orbit planets)

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3
Q

What is our solar system a small part of?

A

The Milky Way Galaxy

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4
Q

How do stars form?

A
  • stars form from a cloud of dust and gas (nebula)
  • gravity causes the cloud of gas and dust to collapse (collapsing cloud of hot gas and dust is a ‘protostar’) => as the dust particles move faster, temperature rises to millions of degrees celsius
  • if the temperature of the protostar gets high enough, then hydrogen nuclei join together to form helium (process is called nuclear fusion) => protostar => star
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5
Q

What does nuclear fusion release?

A

a huge amount of energy

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6
Q

What happens a star that is undergoing nuclear fusion?

A

There are two opposing forces acting within the star:

  • force of gravity acts inwards => causes the star to collapse
  • energy from nuclear fusion creates a force acting outwards => causes the star to expand
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7
Q

What forces are balanced?

A
  • the force of gravity acting inwards is balanced by the force due to fusion energy acting outwards

=> star is in equilibrium

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8
Q

What is a star’s life cycle determined by?

A

the size of the star

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9
Q

What happens in a main-sequence star when the hydrogen begins to run out?

A
  • the outward force due to fusion energy is less than the inward force due to gravity => star collapses inwards => temperature increases =>
    helium nuclei fuse together to create heavier elements => star expands to form a red giant
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10
Q

What happens when a red giant stops fusing helium?

A
  • star shrinks and forms a whte dwarf (no longer carrying out fusion so it gradually cools down)
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11
Q

What is formed when a white dwarf eventually stops releasing any energy?

A
  • when the white dwarf stops releasing any energy, a black dwarf is formed
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12
Q

What happens when a star, that is much bigger than our Sun, runs out out hydrogen?

A
  • they leave the main-sequence stage and expand into red super giants
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13
Q

What is similar with smaller stars like the Sun and the red super giants?

A
  • helium nuclei fuse together to produce heavier elements
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14
Q

What is the heaviest element that nuclear fusion can make with a star that is the same size as the Sun?

A
  • nuclear fusion cannot make elements heavier than iron
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15
Q

What happens when red super giants stop carrying out nuclear fusion?

A
  • the star explodes => supernova
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16
Q

How can supernovas create elements heavier than iron?

A
  • temperature of a supernova is high enough to produce elements heavier than iron (when the supernova explodes, these elements are distrubed throughout the Universe)
17
Q

What 2 objects can form after a supernova?

A
  • neutron star
  • black hole
18
Q

What does a neutron star consist of?

A
  • neutrons densely packed together
19
Q

What is special about a black hole?

A
  • a black hole has such a large gravity that not even light can escape
20
Q

What is it called when the Earth rotates around the Sun?

A
  • a circular orbit as the Earth follows the path of a circle around the Sun
21
Q

What is the more realistic orbit called?

A
  • elliptical orbit
22
Q

How do planets and satellites maintain their circular orbits?

A
  • gravity provides the force (e.g. the force of gravity acting between the Sun and the Earth holds the Earth in its orbit)
23
Q

Give an example of a natural satellite?

A
  • the Moon is a natural satellite
24
Q

Give an example of an artifical satellite?

A
  • the International Space Station
25
Q

What is the difference between artifical satellites and natural satellites?

A
  • artificial satellites are man-made that can be used to study the Earth, other planets, to help us communicate, and even to observe the distant Universe
26
Q

What are geostationary satellites?

What does this mean about their position to the Earth?

A
  • geostationary satellites orbit once every 24hours
  • as the Earth takes 24hours for one full spin, the geostationary satellites always point to the same part of the Earth
27
Q

Why does the force of gravity acting on satellites lead to a change in velocity but not a change in speed?

A
  • velocity is a vector quantity (involves magnitude AND DIRECTION) so the direction is always changing but the speed remains constant
28
Q

What happens to the radius of a satellite’s orbit is the speed increases?

Why does this happen?

What does this relationship lead to?

A
  • if a satellite orbits at an increased speed, then the radius of the satellite’s orbit decreases
  • at a greater speed, the satellite needs a greater force of gravity to prevent it flying off into space (satellite comes closer to the Earth)

=> stable orbit

29
Q

In the 1900s, what did astronomers detect about the light from distant galaxies?

A
  • they detected that the light from very distant galaxies had an increased wavelength compares to light from closer galaxies
30
Q

On a spectrum, how can we identify absorbed wavelengths?

A
  • certain elements absorb light of specific wavelengths => those specific wavelengths appear as dark, vertical lines
31
Q

On a spectrum of light from a distant galaxy, what will we notice about the absorbed wavelengths of light?

What do scientists call this effect?

A
  • all the lines will have shifted slightly towards the red end of the spectrum

(red-shift)

32
Q

What does the red-shift tell us?

A
  • galaxies are moving away from each other (observed wavelength is increased)
33
Q

How can we identify fast-moving galaxies?

A
  • galaxies that are further away have a bigger red-shift so these galaxies are moving faster than galaxies that are closer
34
Q

What does red-shift provide evidence for?

A
  • the fact that distant galaxies are moving faster than nearby galaxies provides evidence tat hee universe is expanding (supports The Big Bang theory)
35
Q

What do scientists believe about The Big Bang theory?

A
  • scientists believe that the universe began from a very small region that was extremely hot and dense…which expanded into the universe we see today
36
Q

What did observations of supernovae sugest?

A
  • scientists used to think that due to gravity, the expansion of the Universe would slow down
  • observations of supernovae suggest that distant galaxies are actually receding increasingly faster
37
Q

Give 2 examples of what is still not understood about the Universe.

A
  • dark mass/matter
  • dark energy

Physics (5 decks)

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