Untitled Class > Astronomy #3 > Flashcards

Astronomy #3 Flashcards

(115 cards)

Study These Flashcards
1
Q

Wavelength

A

The length from one point on a wave to the point where it is repeated exactly in space at a given time.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Frequency

A

The number of wave crests passing any given point per unit of time.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Amplitude

A

The maximum deviation of a wave above or below the zero point. Larger amplitude of wave equals more intensity of light.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Waves (symbols)

A

v = speed
f = frequency
wavelength = λ

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Light (symbol and speed)

A

v = light
speed of light = 300,000,000 m/s

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

James Clerk Maxwell

A

Scottish physicist and mathematician who was responsible for the classical theory of electromagnetic radiation.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Classical theory of electromagnetic radiation

A

the first theory to describe electricity, magnetism, and light as different manifestations of the same phenomenon.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Electric Field

A

A field extending outward in all directions from a charged particle, such as a proton or electron.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Electromagnetic wave

A

composed of an oscillating electric field and a magnetic field oscillating perpendicular to it.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Electromagnetic radiation

A

transfers energy and information from one place to another, even through the vacuum of empty space, through fluctuating electric and magnetic fields.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Radiation

A

any way in which energy is transmitted through space from one point to another without the need for any physical connections between the two locations.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

visible light

A

only makes up a small part of the electromagnetic spectrum (400 to 700 nm), corresponding to blue through red light.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Limitations of optical telescopes on earth

A

Available Sky: you can only see part of the sky at any given time on a particular night.
Atmospheric Absorption: blurring of images caused by atmospheric “heat waves”, which cause images to shimmer.
Light Pollution: growth of night time lights has distanced us from the night sky.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Radio telescope

A

A curved metal dish made of mesh wires that captures cosmic radio waves and reflects them to the focus, when then collects them and directs them to a computer.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Interferometer

A

A collection of several telescopes observing the same object at the same time and at the same wavelength. The effective diameter of an interferometer is equal to the distance between its outermost telescopes.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

The Start of Interferometry

A

The first successful long distance interferometry experiment ever conducted was in 1968 in Canada.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Infrared Astronomy

A

Water vapour in the atmosphere absorbs most IR. Lightweight telescopes are carried above most of earths atmosphere by balloons, airplanes, and satellites. Discovered the presence of dust-disks around nearby stars, presenting us with the first evidence of planets orbiting other stars.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Ultraviolet Astronomy

A

Earths atmosphere is partially opaque to ultraviolet wavelengths. UV telescopes are put on rockets or satellites to get high above most or all of the atmosphere. Valuable insight into hot stars and ionized clouds of gas.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

X-Ray Astronomy

A

Observed x-ray bursts coming from heated gas around compact massive objects, like black holes. Important discoveries about everything from star formation to monster black holes in distant galaxies.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Spectroscopy

A

The process of dispersing light into its spectrum (different wavelengths), and the study of the way in which atoms absorb and emit electromagnetic radiation. Allows astronomers to determine the chemical composition of stars by:
- observing the spectral lines formed by different elements in the laboratory.
- comparing these with the spectra from astronomical objects.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

The visible part of the EM spectrum

A

Blue (violet) light with

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Kirchoff’s Law 1

A

The Continuous spectrum: A solid, liquid, or dense gas excited to emit light will radiate at all wavelengths and thus produce a continuous spectrum.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Kirchhoff’s Law 2

A

The Emission Spectrum: A low density gas excited to emit light will do so at specific wavelengths, and produce an emission spectrum.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Kirchhoff’s Law 3

A

The Absorption Spectrum: If light comprising a continuous spectrum passes through a cool, low-density gas, the result will be an absorption spectrum.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Continuous Spectrum
Also known as thermal. the spectrum of a common (incandescent) light bulb spans all visible wavelengths, without interruption. Only hot & dense objects emit the continuous spectrum.
26
Emission Line Spectrum
A thin or low-density cloud of gas when heated emits only at specific wavelengths that depend on its composition and temperature, producing a spectrum with bright emission lines.
27
Absorption Line Spectrum
A cloud of gas between us and a light source can absorb light of specific wavelengths, leaving dark absorption lines in the continuous spectrum.
28
Blackbody Radiation
The radiation emitted by an opaque object.
29
Properties of Thermal Radiation
Stefan Boltzmann Law: Hotter objects emit higher energy than cooler objects. Wien's Law: The hotter the object, the bluer its radiation.
30
The Doppler Effect
Sound, such as engine noise or emergency sirens, is shifted to shorter wavelengths and higher pitches as it is approaching. The sound is shifted to longer wavelengths and lower pitches after it passes by.
31
Blueshift (shorter wavelength)
an objects motion towards you
32
Redshift (Longer wavelength)
an objects motion away from you
33
Photoelectric effect
A beam of light knocks electrons loose from a substance to produce a flow of electricity. When electrons are ejected from a material (like metal) when light hits it, proving that light acts as particles (photons).
34
E = hf
E represents energy, f represents frequency, and h equals Plank's constant
35
Planks Law
the radiation intensity increases with temperature, and shifts to shorter wavelengths as the temperature rises.
36
Planks Constant
A fundamental physical constant in quantum mechanics, representing the smallest unit of energy exchange, linking a photons energy to its frequency with the equation E = hf
37
Hydrogen's visible light spectrum
always consists of two violet lines, a blue-green line, and a bright red one.
38
allowed Orbitals
An electron can only orbit around an atom at specific orbits
39
Radiationless Orbits
An electron in an allowed orbit does not emit radiant energy, so long as it's in the orbit.
40
Quantum Leaps
An electron gains or loses energy only by moving from allowed orbit to another. The lowest energy state is known as the ground state. Higher states are known as excited states
41
Bohr's model
electron orbits the nucleus and can only orbit in specific orbits
42
Absorption of light by Atoms
In the hydrogen atom, the electron jumps from orbit 2 to 3 by absorbing a photon with a specific wavelength. This photon has exactly the required energy to make the jump possible. Emission is the same, just from 3 to 2
43
Chemical Fingerprints in Light
Each type of atom, ion and molecule has a unique ladder of energy levels that electrons can occupy
44
Quantum Mechanics
states that light and matter, including electrons, have a dual nature of both particles and waves.
45
De Broglie Waves
An orbit in which the standing wave pattern will just fit in the circumference of an orbit, which is an allowed orbit.
46
Pauli Exclusion Principle
No two electrons can have the same set of quantum numbers. At least one of the quantum numbers must differ.
47
Heisenberg uncertainty principle
the position and velocity (momentum) of a particle cannot be simultaneously determined. The more precisely we measure the position, the greater the uncertainty of the velocity, and vice versa. Thus, a quantum principle cannot be assigned a definite trajectory.
48
Quantum fluctuations
small particles, like electrons, deviations from classical motion can be very large and unpredictable.
49
Wave Mechanics
Electrons do emit light in certain wavelengths based on their energy levels. Since waves spread out from the electron, the wave mechanic model predicts an area where an electron would be found, and not a specific place where it would be found.
50
Many Worlds Interpretation
All possible outcomes of any measurement do occur, but they occur in "parallel" universes, which have no contact with one another. With every measurement of a particle's position, the universe branches into multiple copies of itself, where the particle is found to be in all possible places.
51
Distance Ladder
The calibration used to build a distance scale extending from the size of the earth to the most distant visible galaxies.
52
Standard Candles
object of known brightness that astronomers use to find distance using the true luminosity and the inverse square law. There are certain classes of stars which have a small range of luminosities.
53
Stellar Parallax
The apparent shift in position of a nearby object/star against a background of more distant objects. Parallax angel depends on the distance. The further the object, the smaller the parallax angle. Parallax is caused by the earth's motion around the sun.
54
Apparent Brightness
The amount of a stars light which reaches us per unit area. The apparent brightness depends on two things: 1) how much light it is emitting (Luminosity), also known as it's intrinsic brightness 2) how far away it is (distance)
55
The inverse square law
as light radiates away from its source, it spreads out in a way that the energy/brightness decreases with the square of the distance from its source
56
Cepheid Variables
Variable stars are one of the most reliable types of "Standard Candles". They are giant stars whose instability causes them to pulsate in size, temperature and luminosity. The longer the period, the greater the luminosity.
57
End of Life of a Sunlike Star
1. when nuclear fusion exhausts a stars fuel, gravity collapses the core 2. Hydrogen starts to fuse rapidly to Helium in a shell around the core 3. luminosity increases because the fusion rate is higher 4. outer layers increase in size, becoming a red giant
58
White Dwarf Phase
consists predominantly of Carbon and Oxygen. Shrinks in size, but has more mass than the sun.
59
Edwin Hubble
Proved that our Milky Way is only one of a multitude of galaxies in the cosmos. in 1923, he identified Cepheid Variable stars in Andromeda.
60
Conservation Laws
Statements telling us that some quantity does not change. Energy cannot be created nor destroyed. Energy can only be transformed from one form to another.
61
Forms of energy
- mechanical - chemical - electromagnetic - nuclear
62
Types of Mechanical Energy
Potential Energy: "the idea of doing something". Gravitational, chemical, elastic and electromagnetic. Associated with the systems position or orientation (u). Kinetic Energy: "doing something". Moving objects, heat, sounds waves, and any other waves. The energy associated with an objects motion (k).
63
Potential Energy (u)
the energy a system has due to interactions between its parts. can be thought of as "Stored energy". No universal formula.
64
Kinetic Energy (k)
The energy an object has because of its motion. An object of mass travelling with speed (v) has kinetic energy.
65
Conservation of Mechanical Energy
In an isolated system, to which no external forces are applied, the total energy is conserved- it does not change with time.
66
Conservation of Energy & Kepler's II Law
A planet moving along its elliptic orbit speeds up as it gets closer to the sun, and slows down as it gets further away.
67
Escape Speed
The minimum initial speed in which the object must be launched in order for it to escape from the earth.
68
Problems with an infinite static universe
Gravitational Instability: uniform distribution of stars is unstable due to gravity. Olber's Paradox: The night sky is dark. If Newton's claim was true, your line of sight should eventually reach the surface of a star.
69
Homogeneous space
All points have the same properties
70
Isotropic Space
all directions have the same properties
71
Einstein's Cosmological Constant
a uniform energy density filling space, also known as vacuum energy, that exerts an outward force, driving the accelerated expansion of the universe. An amount of energy, positive or negative, that is inherent to the fabric of spacetime itself.
72
Thermal Equilibrium
the state reached when two or more objects in physical contact stop exchanging heat energy because they have reached the same temperature
73
Thermal Fluctuations
Spontaneous reductions of disorder occasionally happen by chance in thermal equilibrium
74
The Universe
everything that exists
75
The Observable Universe
the part of the universe that we can see
76
Friedmann's Closed Universe
As the galaxy expands, we should see all the other galaxies moving away. During contraction, all galaxies would approach ours. Time runs from the bottom up.
77
Einstein's Static Universe Assumptions
- The universe is homogenous and isotropic and has closed spherical geometry
78
Flat Universe
Borderline case between open and closed solutions is a "flat" universe, having Euclidean geometry.
79
Georges Lemaitre
Belgian mathematician and priest who rediscovered the expanding universe models in 1927, and discovered Hubbles Law, two years before Hubble did, but was called the expanding universe theory.
80
Doppler Effect
Blueshift: Has shorter wavelengths, indicating motion towards you Redshift: Has longer wavelengths, indicating motion away from you
81
Hubbles Law
Galaxies are moving away from earth at speeds proportional to their distance
82
The Cosmological Redshift
caused by the stretching of photon wavelengths as they travel though expanding spacetime. Wavelengths change to red and stretch the longer they're in space.
83
Hubbles Constant
describes the universe's rate of expansion
84
The Cosmological Principle
The "starting point" in time of the Big Bang. States that the universe is homogeneous and isotropic.
85
The Edge Centre Problem
The universe doesn't seem to have an edge, therefore it cannot have a centre.
86
Particle Horizon
We are at the centre of a theoretical sphere- the observable part of the universe. This is the boundary of this "sphere".
87
Main Observations explained by The Big Bang
- expansion of the universe - primordial nucleosynthesis - cosmic background radiation
88
Primordial Nucleosynthesis
Happened right after the Big Bang, the formation of the universes lightest elements/atomic nuclei (Helium, Hydrogen, and a little bit of Lithium).
89
Order of The History of The Universe
1. elementary particles 2. protons, neutrons, electrons and neutrinos 3. Plasma of Hydrogen and Helium nuclei 4. Atoms and Plasma, stars begin to form 5. stars, galaxies, and clusters
90
Conservation of energy
An expanding sphere will eventually collapse or keep expanding forever. The way the sphere behaves depends on whether the total energy is negative, positive or zero.
91
Critical Density
the theoretical, precise average density of matter and energy in the universe required to create a perfectly "flat" geometry. The universe will expand forever, but will eventually slow to zero.
92
Open Universe
space-time is curved in such a way that the universe is infinite. Low density universe whose expansion is also slowing down.
93
Closed Universe
Space-time is curved to meet itself, and the universe is finite. High density universe which expands for billions of years, then turns around and collapses under its own weight
94
positive curvature
number of galaxies increases with greater volumes, then decreases with very large volumes. Lines defining an angle spread out at first, and then converge at great distances.
95
Negative curvature
number of galaxies increases more rapidly with ever greater volume than a flat universe. Lines defining an angle diverge at increasing
96
zero curvature
the galaxies are spread roughly uniformly in the universe -- number of galaxies should increase linearly with ever greater volume.
97
Flat universe
More of a horizontal curve; Critical density universe in which the expansion rate continually slows down.
98
cosmological constant/dark energy
The "nothingness" that fills the universe and causes galaxies to move away from each other.
99
The Milky Way
A spiral galaxy with over. 400 billion stars and three general components: -The Halo: a roughly spherical distribution which contains the oldest stars in the galaxy. -The Nuclear bulge and Galactic Center -The Disk, which contains most of the stars, including the sun, and virtually all gas and dust
100
Rotation Curve
Represents the velocity of particles versus distance from the centre of rotation.
101
Keppler's third Law
Find the mass of the part of the galaxy contained within the star orbits with measured sizes and speeds.
102
Newton's form of Keppler's III law
Deduce the mass of the Milky Way at different distances from the centre.
103
Dark Matter
Nonluminous matter that is detected only by its gravitational influence.
104
Groups
The name of the smallest aggregates of galaxies. Will have fewer than 50 galaxies. Our local group, The Milky Way, has around 40 galaxies
105
Missing Mass Problem
Out of calculated mass of the cluster, only a fraction can be identified with visible matter/matter that is emitting light
106
Estimating gravitational mass
1. observing galaxies orbiting the massive central elliptical galaxies. Galaxies move like bees around a hive, and from their orbits and velocities, we can calculate the mass of a cluster. 2. Gravitational Lensing, on the other hand, is the effect a cluster has on light from objects in the background.
107
Gravitational Lensing
the effect a cluster has on light from objects in the background.
108
Possible solutions for the difference in observed and gravitational mass
1. Dark Matter really exists, and we are observing the effects of its gravitational attraction. 2. Something is wrong with our understanding of gravity, causing us to mistakenly infer the existence of dark matter
109
Ordinary Matter
baryonic matter made up of baryons, being protons and neutrons
110
extraordinary matter
also referred to as undiscovered matter and is non-baryonic. Extraordinary matter is WIMP, Weakly-interacting Massive Particles: mysterious neutrino-like particles
111
Evidence of the Big Bang Theory
1. Expansion of The Universe/Hubble's Law 2. Abundance of light elements 3. CBM (Cosmic Background Microwave) radiation 4. Evolution and distribution of galaxies
112
Expansion of The Universe/Hubble's Law
Production of elements in the Big Bang. The early universe was full of particles and radiation because of its high temperature. This is when nucleosynthesis (production of light elements) took place.
113
CBM (Cosmic Background Microwave) Radiation
We have detected leftover radiation from the Big Bang
114
BAO (Baryonic Acoustic Oscillations)
regular, periodic fluctuations in the density of visible normal matter of the universe, originating from sound waves in the hot, dense plasma of the early universe.
115
Untitled Class
flashcards
Decks in class (3)
# Cards
Brainscape helps you reach your goals faster, through stronger study habits.
© 2026 Bold Learning Solutions. Terms and Conditions