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Chris Kanubaddi - Science Sem2 > Big Bang Theory > Flashcards

Big Bang Theory Flashcards

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1
Q

What is the Heliocentric Model?

A

The astronomical model that places the Sun at the centre of the Solar System and eight planets, including Earth, in orbit around it.

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2
Q

Where are stars formed?

A

Stars are formed in nebulae, which are large clouds of dust and gas in space.

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3
Q

Why do stars appear in different colours?

A

Due to their surface temperature.

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4
Q

What colours do stars appear?

A

Cooler Stars (3000K): red-orange due to infrared and red light.
Med-temp Stars (5500K): Yellow - balanced light spectrum (Sol).
Hotter Stars (10000K+): blue or white due to ultraviolet and blue light.

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5
Q

How old is the universe?

A

The universe is approximately 13.7 billion years old, with 200 million years of uncertainty.

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6
Q

List the Universe Hierarchy

A
  1. Universe
  2. Galaxies
  3. Solar Systems
  4. Planets, Dwarf Planets, Moons, Asteroids, Meteors, Space Debris.
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7
Q

What is in our Heliocentric Solar System?

A

The Sun (Sol) is at the centre, orbited by 8 planets in the following order from the Sun.
Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.
5 Dwarf Planets: Ceres, Pluto, Haumea, Makemake and Eris

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8
Q

What makes a planet?

A
  1. Orbits the host star of the System
  2. Mostly Round
  3. Big enough that its gravity cleared away all other objects of similar size in its orbital path around the Sun (this is why Pluto was reclassified as a dwarf planet).
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9
Q

What makes a moon?

A

Objects that orbit a planet rather than the sun are classified as moons. They are also known as natural satellites.

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10
Q

What are galaxies made of?

A

Galaxies are concentrations of stars, gas, dust, and dark matter held together by gravity.

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11
Q

What are the 3 major categories of shapes in galaxies?

A
  1. Elliptical
  2. Spiral (The Milky Way)
  3. Irregular
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12
Q

What is the universe?

A

The universe is everything. It includes all of space and all the matter and energy that space contains. It even provides time itself and, of course, it includes you.

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13
Q

How many galaxies are in the observable universe?

A

The Milky Way is but one of the trillions of galaxies in the observable universe.

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14
Q

What is in the centre of all galaxies?

A

All of them, including ours, are thought to have supermassive black holes at their centres.

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15
Q

What is a black hole?

A

A black hole is an area of such immense gravity that nothing - not even light can escape it.

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16
Q

What is the relationship between Galaxies, Stars and Solar Systems?

A
  1. Millions of Stars in a Galaxy
  2. Each star in the galaxy has its orbiting planets and moons.
  3. These celestial bodies orbit the sun, and as a whole, this is called the solar system, with the sun being at its centre.
  4. Our Star, the Sun (Sol), is within the Milky Way galaxy and is surrounded by celestial bodies, such as planets and moons.
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17
Q

What are constellations?

A

Constellations are grouped stars by ancient astronomers. According to the shapes they seemed to form. The shapes were usually of gods, animals or familiar objects.
The most well-known constellations are the twelve groups we know as the signs of the zodiac.

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18
Q

How many constellations are there currently found?

A

Today, astronomers recognise 88 constellations.

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19
Q

What is the prominent constellation visible from Australia?

A

The Southern Cross (Crux Australia) is easily visible just after sunset in the Southern Hemisphere.
Just below it is the Emu in the Sky. The dark patches of the Milky Way, the space between the stars, form the emu.

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20
Q

Are stars in constellations next to each other in space?

A

No. When observed from Earth, the stars in each constellation appear to be very close to each other. However, the stars that makeup constellations can be located at very different distances from Earth.

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21
Q

How do constellations change in the sky?

A

The apparent motion of the fixed pattern of stars at night, shown in time-lapse photography, is due to the rotation of Earth.
The apparent change in position of the constellations is due to Earth’s orbit around the Sun.

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22
Q

What is the principle of Parallax?

A

The principle of parallax is the apparent shift in the position of an object when viewed from two different points. This shift allows astronomers to measure the distance to nearby stars by observing their position from Earth and a separate location (such as Earth’s orbit around the Sun).

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23
Q

What is an Astronomical Unit (AU)?

A

The distance from Earth to the Sun is called the astronomical unit (AU).

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24
Q

How long is one Astronomical Unit (AU)?

A

The Astronomical Unit (AU) was calculated to be approximately 150 million kilometres.

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25
Q

How was the Astronomical Unit (AU) measured?

A

The distance between two observers on Earth can be calculated using geometry by knowing the distance between them and timing Venus’s transit as the planet moves across the face of the Sun. This relies upon the principle of parallax.

26
Q

What is the next Astronomical Unit?
DISCLAIMER: (this info is just content and does not need to be memorised.)

A

It is called a Parsec.
This is very useful to astronomers as it is calculated directly from observed angles. One parsec, by definition, is the distance to an object whose parallax angle is one arcsecond (1/3600 of a degree).
The radius of Earth’s orbit equals one astronomical unit, so an object that is one parsec distant is 206 265 AU.

27
Q

What is a light-year?

A

A light-year is not a measure of time. It’s a measure of distance. It is the distance that light travels in one year.

28
Q

What are the most common measures of light-years?

A

Speed: 300,000 km/s
Distance:
1. 9,500,000,000,000 kilometres
2. 9.5 × 10^12 kilometres

29
Q

What is the process of the birth of a star?

A
  1. Stars begin as a collection of dust and gas called a nebula.
  2. When the dust and gas are dense enough, gravity takes over, and the gas and dust collapses, forming a cloud.
  3. This dense cloud is now called a protostar.
  4. The temperature of a protostar is not high enough for any reactions to occur, but with increasing pressure, the temperature increases.
  5. Once they are high enough, nuclear fusion occurs!
30
Q

What is nuclear fusion?

A

Nuclear fusion is where two isotopes of hydrogen (deuterium and tritium) combine to form Helium, along with the release of a neutron and energy (in the form of immense amounts of heat and light).

31
Q

What is apparent magnitude?

A

The brightness of a star as seen from Earth.
The scale ranges from -30 (brightest) to +30 (dimmest).
The full moon has an apparent magnitude of -13, and the sun is -27.

Some stars seem brighter due to proximity to Earth, but aren’t necessarily brighter than others.

32
Q

What is absolute magnitude?

A

Actual brightness of a star.
It is calculated by determining the distance of the star from Earth.

33
Q

What is the star spectra?

A

The spectrum of white light from a nearby star. The black lines show which colours have been absorbed by elements in the star. The numbers indicate the wavelength of the light in nm.

34
Q

How is the star spectrum analysed?

A

To classify stars, scientists looked up the spectrum of light and photographs of the stars.
When the spectrum of light from a star is analysed, some dark lines are observed.
These dark lines correspond with the colours of light absorbed by substances in the star.
Different substances absorb different colours of light.
Astronomers can determine which elements are present in a star by identifying the wavelengths of the colours missing from the spectrum.

35
Q

What is the Red Shift?

A

The shift of lines of a spectral pattern towards the red end of the spectrum (lower frequencies) when the light source moves away from the observer.

36
Q

What is the Blue Shift?

A

The shift of lines of a spectral pattern towards the blue end of the spectrum (higher frequencies) when the light source moves toward the observer.

37
Q

What is Hubble’s Law?

A

The further a galaxy is away from the Earth, the greater its red shift and the faster its moving away from us.

38
Q

What is a Hertzsprung–Russell (HR) diagram?

A

It is a scatter plot of stars showing the relationship between the stars’ absolute magnitudes (or luminosities) versus their surface temperatures or (stellar classifications).

39
Q

What are used in other types of HR diagrams?

A

Some use Luminosity, and some use stellar classifications (white dwarf, supergiants, etc.)
Luminosity is an absolute measure of radiated electromagnetic power (light), the radiant power emitted by a light-emitting object. In astronomy, values for luminosity are often given in terms of the Sun’s luminosity.

40
Q

What is the death of a star?

A

The death of a star details the process by which a star undergoes a sequence of radical changes during its lifetime.

41
Q

Name the lifecycle of a star in order.

A
  1. Stellar Nebula → Normal Main Sequence Star → Red Giant → Planetary Nebula → White Dwarf → Black Dwarf.
  2. Stellar Nebula → Massive Main Sequence Star → Red Supergiant → Supernova → Neutron Star / Black hole.
42
Q

What are the 2 main theories of the universe?

A

The Big Bang Theory and the Steady State Theory.

43
Q

What does the Big Bang Theory suggest?

A

The universe began 13.7 billion years ago with a ‘big bang’.
It started from a hot single point called a singularity.
It expanded from the single point and is still cooling down.
The space between galaxies is increasing as the universe expands.

44
Q

What does the Steady State Theory suggest?

A

The universe has no beginning and no end.
The space between galaxies remains constant because as the universe expands, new stars and galaxies are continuously created to replace the old and unobservable ones.

45
Q

What happened after the Big Bang during the formation of matter and stars?

A

Positrons and electrons collide to form light energy, creating protons, neutrons, and light elements like hydrogen, helium, and lithium.
As the universe expanded and cooled, atoms formed when nuclei captured electrons, allowing light to escape and ending the dark era.
Gravity pulled hydrogen, helium, and lithium together, forming the first stars and planets, followed by galaxies in regions with stronger gravitational forces.

46
Q

What are the 4 pieces of evidence of the Big Bang Theory?

A
  1. Einstein’s Equation
  2. The Red Shift
  3. The Elements
  4. Cosmic Microwave Background Radiation
47
Q

How does Einstein’s Equation support BBT?

A

The one major flaw with the Big Bang Theory (BBT) was that everyone agreed that matter could not just appear from nothing. However, once Einstein proposed that Energy could be changed into matter, the BBT suddenly made a lot more sense.

E=mc^2 proved matter could be made from energy and vice versa.

48
Q

How does Red Shift support BBT?

A

The discovery of the red light shift provides evidence for an expanding universe, supporting the BBT.

49
Q

How does the Elements evidence support BBT?

A

The vast amounts of hydrogen and helium in the Universe support the BBT.
Steady State Theory (SST) suggests that Helium is only made via Nuclear fusion in stars. However, 8.7% of atoms in the Universe are Helium, which is much more than can be produced by stars. This disproves SST. BBT can explain the high percentage of Helium atoms.

50
Q

How does Cosmic Microwave Background Radiation support BBT?

A

In 1948, it was proposed that 15 billion years after creation (now), the universe would have a temperature of 2.7˚C above absolute zero.
Anything with a temperature above absolute zero emits radiation, and the nature of the radiation depends on the temperature.
It was predicted that because of the Universe’s temperature, it would emit some radiation, which became known as Cosmic Microwave Background Radiation. Engineers picked up a consistent radio noise that they couldn’t get rid of, and they discovered that it wasn’t coming from anywhere on Earth.

51
Q

What is the electromagnetic spectra?

A

The electromagnetic spectrum is the range of all types of electromagnetic radiation, classified by wavelength or frequency. It includes radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays.

52
Q

What do radio telescopes measure?

A

Radio telescopes detect radio waves emitted by stars and galaxies, travelling at 300,000 km/s like other electromagnetic waves.

53
Q

What do radio telescopes look like, and what can they do?

A

These telescopes use large dishes to collect waves, reflect them to an antenna, and analyse them via computers to create images.
They are highly sensitive, detecting minimal energy and signals from far greater distances than light telescopes.

54
Q

What is a satellite?

A

A satellite is a machine or natural object that orbits a planet or star.

55
Q

How many satellites are there for Earth?

A

More than 2,500 satellites orbit Earth, and many constantly monitor its surface and atmosphere. Others provide views of the Universe that could never be seen from Earth’s surface.

56
Q

What is the James Webb Space Telescope (JWST)?

A

The James Webb is an infrared observatory orbiting the Sun around 1.5 million km above Earth.

57
Q

What is the International Space Station (ISS)?

A

The primary purpose of the ISS was to provide laboratories in space for research into microgravity and fields such as medicine, geology and technology.
The ISS also provides the opportunity to investigate the effect of a space environment on humans and prepare for the exploration of Mars and beyond.
The ISS orbits Earth once every 90 minutes.

58
Q

What is Dark Matter?

A

Dark matter is an invisible, massive substance that makes up about 27% of the universe. It has mass and gravitationally influences galaxies and stars, holding them together despite their rotation speed. Dark matter is essential for explaining the structure and stability of the universe.

59
Q

What is Dark Energy?

A

Dark energy is a mysterious force driving the accelerated expansion of the universe. It makes up about 68% of the universe’s total energy content. Unlike dark matter, dark energy doesn’t have mass or directly interact with matter but counteracts gravity, pushing galaxies apart. Its nature is poorly understood but essential for explaining the universe’s observed dynamics.

60
Q

What is a black hole?

A

A black hole is a region in space where gravity is so strong that nothing, not even light, can escape. It is often formed from collapsed massive stars after a supernova.

61
Q

How do black holes form?

A

Stellar black holes form when the centre of a very massive star collapses upon itself. This collapse also causes a supernova, or an exploding star, that blasts part of the star into space.

62
Q

What is Dreamtime according to First Nation’s Australians?

A

First Nations Peoples believe the Dreamtime marks the beginning of the world, where Ancestors, as Spirits, created the land, rivers, animals, and people. They also gave tribes their tools, lands, totems, and Dreaming, shaping the world in the distant past.

Chris Kanubaddi - Science Sem2 (3 decks)

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