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Astronomy Flashcards

(55 cards)

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1
Q

Exoplanets

A

Planets outside our solar system

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2
Q

Satellites def

A

Something that orbits something else

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3
Q

Artificial satellites e.g.

A

Probes, rovers and landers

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4
Q

Galaxy def

A

A collection of billions of stars

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5
Q

Meteors

A

When a small body of matter from outer space enters the earth’s atmosphere (emits light (incandescent) as a result of friction)

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6
Q

Comets

A

Ice and dust with a tail of gas pointing away from the sun as the suns heat vaporises material from the surface (orbit around the sun in ellipsis)

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7
Q

Meteoroid

A

A small particle from a comet or asteroid orbiting the sun

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8
Q

Meteorite

A

A meteoroid that survives its passage through earth’s atmosphere and lands on earths surface

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9
Q

Asteroid

A

A small rocky body orbiting the sun

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10
Q

Where is the asteroid belt?

A

Between Mars and Jupiter

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11
Q

Lightyear

A

Distance travelled by light in one year

(9.46x10^15 m) —> 3x10^8 x 365 x 24 x 60 x 60

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12
Q

Why does weight change depending on where you are in space?

A

Weight is the mass of an object multiplied by its gravitational field strength. This changes in different places in space therefore weight changes (but mass stays the same)

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13
Q

Solar system order

A

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

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14
Q

Dwarf planets

A

Pluto, Makémaké, Eris,

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15
Q

Artificial satellite def

A

One which has been put into orbit around the earth by human beings

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16
Q

Uses of artificial satellites

A

To monitor weather, for communication, navigation

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17
Q

Two main orbits

A

Low polar orbit (parallel to north and south poles) e.g. Observation and monitoring orbits - scans the whole surface due to the spin of the earth, and geostationary orbit (perpendicular) above the equator e.g. Communications satellite - stays in the same place orbiting earth as it moves at the same rate

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18
Q

How do planets or it the sun?

A

Ellipsis

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19
Q

Models of the solar system

A

Geocentric, heliocentric

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20
Q

The further a planet is from the sun…

A

… the slower it moves and the more time is takes to complete an orbit

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21
Q

Orbital speed eq

A

2 x pi x orbital radius/time period
v = 2 x pi x r/T
(Time period is the time it takes to make one full orbit around the object)

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22
Q

Gravitational field strength on moon

A

1.6 N/kg

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23
Q

What is a year in terms of a planet

Study These Flashcards
A

The time it takes to orbit its star

24
Q

Geocentric

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A

Earth is the centre of the solar system

25
Heliocentric
The earth and other celestial bodies revolve around the Sun
26
History of the heliocentric theory
Put forward by Copernicus. Proved by Galileo - looked at Venus and discovered it went through phases, also looked at Jupiter's moons (which looked like stars) and noticed they weren't orbiting earth so it disproved the geocentric model
27
Big Bang theory
13.7 billion years ago. Before, the universe was very dense, hit and extremely small with lots of energy. All matter and energy in the universe was compressed in a very small space (thermodynamic conservation). The Big Bang theory was not an explosion but a large rapid expansion of space. This eventually cooled down to allow atoms to form so Creation took place.
28
What slows the universe's expansion down?
The masses attracting each other. Without gravity, the universe would expand at the same rate forever.
29
Evidence for the Big Bang theory
Other galaxies are moving away from us (red shift). The further away a galaxy is, the faster it is moving away (expanding universe, supports the theory that the universe started with a single explosion).
30
Steady State theory
The universe has always existed as it is now and always will do. It had no beginning but has always been expanding. It was uniform and always existed. It is continuous. It is based on the idea that the universe appears the same everywhere.
31
Evidence for steady state theory
Redshift - matter is being created in the spaces as the universe expands (E=mc^2) - energy can be made c=speed of light
32
Doppler effect
Increase or decrease in the frequency of sound or light as the source and observer moves towards or away from each other. This causes a change in pitch (noticed in red shift)
33
Redshift. How it works.
Provides evidence that the universe is expanding. The sun contains helium. The black lines in the spectrum are where helium has absorbed light. Compared to other distant stars, the pattern has moved (change in frequency of the position of lines). If a galaxy's light is redshifted, it is moving away from earth, (more distant) further and faster.
34
Interpreting red shift/blueshift
Supports both theories. When a source of waves is moving it continues to emit radiation at the same rate of frequency. Blueshift - waves are squashed together, close to the blue end of the spectrum, frequency increases. Redshift - waves are more spread out, close to the red end of the spectrum, frequency decreases, longer wavelength so it is moving away. (Spread to see red)
35
CMBR
Cosmic Microwave Background Radiation. Received from all parts of the universe and is thought to be the heat left over from the original explosion. Shows that the universe has aged as it cooled. Microwaves have low frequencies and longer wavelengths. Could have started with gamma rays which have shorter wave lengths and are the highest energy EM waves. Only supports Big Bang.
36
If a wave source is moving relative to an observer there will be a change in the observed frequency and wavelength. This is called…
The Doppler Effect
37
Compare the theories
Both expansions. Therefore both supported by red shift. BB also supported by CMB radiation. BB has a starting point whereas SS states that it has always existed with no beginning. Redshift in SS refers to energy being made. BB is accepted as there is more evidence to support it with compliments the theory better
38
Nebula
A cloud of dust and gas (mainly hydrogen)
39
Life cycle of stars
Nebula, protostar, main sequence star (small star, red giant, white dwarf, black dwarf - same size as the sun) or (large star, red super giant, supernova, neutron star, black hole - larger than the sun)
40
Energy transfers in star cycle
GPE -> KE (due to gravitational attraction pulling them together) -> heat -> nuclear
41
Formation of protostars
Gravity causes the cloud to collapse by pulling the dust and gas together. GPE is converted to heat energy so the temperature rises. The star gets denser and more particles collide with each other. The hydrogen nuclei undergo nuclear fusion to form helium nuclei. This gives out energy, keeping the core hot
42
Formation of main sequence star
As the gases come together, they get hot. Nuclear reactions start when it is hot enough which releases energy, keeping the star hot. Fusion occurs to produce an outwards force (photon pressure) to balance against gravity. When it is hot enough, hydrogen nuclei undergo thermonuclear fusion to form helium nuclei.
43
Balanced forces in a main sequence star
It is stable because the heat created by the nuclear fusion provides an outward pressure (also from expanding hot gases) to balance gravity inwards. Gravity pulls smaller amounts of dust and gas together to form planets in orbit around the star
44
Formation of a red giant
When all the hydrogen has been used up in fusion, larger nuclei begin to form and expand causing the star to "swell" and the surface cools
45
Formation of a supernova
Large stars with more mass make nuclear reactions, more fusion, get hotter and expand and contract several times until it explodes (leaving behind nebulas)
46
Formation of neutron stars and black holes
The exploding supernova throws outer layers of hot gas and dust into space leaving a very dense core (neutron star). If the star is big enough, it will shrink and become a black hole
47
Formation of a planetary nebula
Star becomes unstable and ejects its outer layer of dust and gas
48
Formation of a white dwarf
Unstable ejection leaves behind a hot, dense solid core (white dwarf) which cools down and eventually disappears
49
Telescope def
A device used to observe the universe
50
Changes in telescopes and benefit
Improved magnification: see further into space, astronomers could identify that some stars were in fact groups of very distant stars - galaxies. We can see all parts of the EM spectrum - structure of the universe. Better resolution: more detail. Gather more light: see faint things better
51
Importance of using telescopes in space
There is light pollution on earth - harder to see dim objects, you can see fainter objects, weather and atmosphere can blur images, see sharper images, can detect EM waves in space, air pollution - can reflect and absorb light from space
52
Optical telescopes. Disadvantages?
Earliest telescopes. Observe visible light from space. They can only be used at night and can't be used in cloudy weather
53
Radio telescopes. Disadvantages vs advantages
Detect radio waves from space. Large and expensive. Can be used in bad weather (radio waves not blocked by clouds as they pass through the atmosphere). Can used in daytime as well as night. Used to discover CMB radiation
54
X-ray telescopes. Disadvantages?
See violent high temperature events in space such as exploding stars. Need to be at high altitudes or flown in balloons
55
Space telescopes
E.g. The Hubble Space Telescope. Can observe the whole sky. Both day and night. See objects a billion times fainter. But difficult to maintain and expensive to launch

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