21St Century Astronomy Ch 1-6, 13-14

Front 1

Moon

Back 1

ANY less massive satellite orbiting a more massive object.

Front 2

Planet

Back 2

Large body that orbits the sun or another star that shines only by light reflected from the star. A body that orbits the sun, has sufficient mass for self-gravity to overcome rigid body forces so that it assumes a spherical shape, and has cleared smaller bodies from the neighborhood around its orbit.

Front 3

Star

Back 3

A luminous ball of gas that is held together by gravity. A normal star is powered by nuclear reactions in its interior.

Front 4

Solar System

Back 4

The gravitationally bound system made up of the Sun, planets, dwarf planets, moons, asteroids, comets, and Kuiper Belt objects, along with their associated gas and dust.

Front 5

Galaxy

Back 5

A gravitationally bound system that consists of stars and star clusters, gas, dust, and dark matter; typically greater than 1,000 light-years across and recognizable as a discrete, single object.

Front 6

Group

Back 6

A small, gravitationally bound collection of galaxies containing from several to a hundred members; typically 1–2 megaparsecs (Mpc) across.

Front 7

Cluster

Back 7

A large, gravitationally bound collection of galaxies containing hundreds to thousands of members; typically 3–5 megaparsecs (Mpc) across.

Front 8

Supercluster

Back 8

A large conglomeration of galaxy clusters and galaxy groups; typically, more than 100–300 megaparsecs (Mpc) in size and containing tens of thousands to hundreds of thousands of galaxies.

Front 9

Universe/Cosmos

Back 9

1. All of space and everything contained therein. 2. Our own universe in a collection of parallel universes that together comprise all that is.

Front 10

Observable Universe

Back 10

Galaxies and other matter that can be observed from Earth, because light has had time to reach the Earth since the beginning of the cosmological expansion.

Front 11

Nebula

Back 11

A cloud of interstellar gas and dust, either illuminated by stars (bright nebula) or seen in silhouette against a brighter background (dark nebula).

Front 12

Light Year

Back 12

The distance light travels in 1 years time.

Front 13

AU

Back 13

The average distance from the Sun to Earth: approximately 150 million kilometers (km).

Front 14

Parsec

Back 14

Short for parallax second. The distance to a star with a parallax of 1 arcsecond (arcsec) using a base of 1 astronomical unit (AU). One parsec is approximately 3.26 light-years.

Front 15

Supernova

Back 15

A stellar explo- sion resulting in the release of tremendous amounts of energy, including the high- speed ejection of matter into the interstel-lar medium

Front 16

Arcsecond

Back 16

A second of arc ("), a unit used for measuring very small angles. An arcsecond is 1/60 of an arcminute, or 1/3,600 of a degree of arc.

Front 17

Arcminute

Back 17

A minute of arc ('), a unit used for measuring angles. An arcminute is 1/60 of a degree of arc.

Front 18

Theory/Hypothesis

Back 18

Hypothesis: A well-considered idea, based on scientific principles and knowledge, that leads to testable predictions.
Theory: A well-developed idea or group of ideas that are tied solidly to known physical laws and make testable predictions about the world. A very well-tested theory may be called a physical law, or simply a fact.

Front 19

Sun's location in our galaxy

Back 19

The Sun orbits the center of the Milky Way galaxy at a distance of approximately 26,000 light-years from the galactic center.

Front 20

Age of the Universe

Back 20

13.7 billion years

Front 21

Age of the Solar System

Back 21

4.6 billion years

Front 22

Galactic Recycling

Back 22

Stars make new elements by fusion, dying stars expel gas and new elements, gas cools, allowing atomic hydrogen clouds to form then molecules, gravity forms that new stars (and planets).

Front 23

Nuclear Fusion

Back 23

The combination of two less massive atomic nuclei into a single more massive atomic nucleus.

Front 24

Distance vs Light Travel Time

Back 24

Light Travel Time is like a "look back" distance, since you are seeing light as it is at you now, as it's traveled from farther way.

Front 25

Relative Scale of Our Solar System

Back 25

http://joshworth.com/dev/pixelspace/pixelspace_solarsystem.html

Front 26

Expanding Universe

Back 26

The expansion of space, the increase of the distance between two distant parts of the universe with time. It is an intrinsic expansion whereby the scale of space itself changes.

Front 27

Big Bang

Back 27

The event that occurred 13.7 billion years ago that marks the beginning of time and the universe.

Front 28

Scientific Method

Back 28

The formal procedure— including hypothesis, prediction, and experiment or observation—used to test (attempt to falsify) the validity of scientific hypotheses and theories.

Front 29

Occam's Razor

Back 29

The simplest solution is probably the right one.

Front 30

Cosmological Principle

Back 30

The (testable) assumption that the same physical laws that apply here and now also apply everywhere and at all times, and that there are no special locations or directions in the universe.

Front 31

Celestial Sphere

Back 31

An imaginary sphere with celestial objects on its inner surface and Earth at its center. The celestial sphere has no physical existence but is a convenient tool for picturing the directions in which celestial objects are seen from the surface of Earth.

Front 32

Ecliptic

Back 32

1. The apparent annual path of the Sun against the background of stars. 2. The projection of Earth’s orbital plane onto the celestial sphere.

Front 33

Circumpolar Stars

Back 33

Describing the part of the sky, near either celestial pole, that can always be seen above the horizon from a specific location on Earth.

Front 34

North Celestial Pole

Back 34

The northward projection of Earth’s rotation axis onto the celestial sphere. Compare south celestial pole.

Front 35

Earth's Tilt

Back 35

About 23 degrees.Right-hand rule (fingers of the right hand are curled around in the direction of the planet's rotation, the thumb points in the direction of the north pole).

Front 36

Phases of the Moon

Back 36

Shape of the illuminated portion of the Moon as seen by an observer, changing relative positions of the Earth, Moon, and Sun. The half of the lunar surface facing the Sun is always sunlit, but the angle seen from the Earth changes.
New moon - Not visible
Waxing crescent - 25 % lit, growing.
First quarter - 50 % lit, growing
Waxing gibbous - 75% lit, growing.
Full moon - 100% lit
Waning gibbous - 75% lit, shrinking.
Last quarter - 50% lit, shrinking.
Waning crescent - 25% lit, shrinking.

Front 37

Seasons

Back 37

Caused by the tilt of the Earth's axis.
Summer is warmer than winter because the Sun's rays hit the Earth at a more direct angle during summer than during winter and also because the days are much longer than the nights during the summer. During the winter, the Sun's rays hit the Earth at an extreme angle, and the days are very short. These effects are due to the tilt of the Earth's axis.

Front 38

Time of Day

Back 38

The axis determines how long days are because of how much time the earth spends facing the sun.

Front 39

True North vs Magnetic North

Back 39

Approximately the same except that magnetic north is the magnetic pull towards the north pole, and true north is the direction directly towards the cosmological north axis.

Front 40

North Star

Back 40

Polaris
the axis of Earth is pointed almost directly at it.

Front 41

Latitude/Longitude
(finding latitude with the stars)

Back 41

The angle between the North Star and the horizon is the Latitude. Longitude is not as easily found with Astronomy.

Front 42

Synchronous Rotation

Back 42

The case that occurs when a body’s rotation period equals its orbital period around another body. A special type of spin-orbit resonance.

Front 43

Parallax and Parallax Angle

Back 43

The displacement in the apparent position of a nearby star caused by the changing location of Earth in its orbit.

Front 44

Solar Eclipse

Back 44

Moon comes between the sun and the earth.

Front 45

Saros Cycle

Back 45

223 month cycle that can be used to predict eclipses of the Sun and Moon.

Front 46

Angular Size

Back 46

as seen from a given position is the size of the object measured as an angle.
angular size in radians = (diameter of planet) / (distance to planet)
Arcmin: angular size in degrees = angular size in radians / 57.296
Arcsec: angular size in arcseconds = angular size in radians / 206265

Front 47

Scientific Models vs Theories

Back 47

A scientific theory is a well-tested hypotheses about some aspect of he world around us.
Scientists often employ a model in order to understand a particular set of phenomena. A model is a mental image of the phenomena using terms with which we are familiar.

Front 48

Geocentric vs Heliocentric

Back 48

Earth centered vs sun centered solar system.

Front 49

Retrograde Motion

Back 49

1. Rotation or orbital motion of a moon that is in the opposite sense to the rotation of the planet it orbits. 2. The clockwise orbital motion of Solar System objects as seen from above Earth’s orbital plane. 3. Apparent retrograde motion is a motion of the planets with respect to the “fixed stars,” in which the planets appear to move west- ward for a period of time before resuming their normal eastward motion.

Front 50

Aristotle

Back 50

proposed 55 concentric, crystalline spheres to which the celestial objects were attached, with the Earth at the center. Suggested epicycles and retrograde motion.

Front 51

Ptolemy

Back 51

Refined Aristotle. All motion is uniform circular motion, made from perfect material, and cannot change their intrinsic properties.

Front 52

Copernicus

Back 52

Suggested a heliocentric model but still adhered to the idea of perfect circles.

Front 53

Galileo

Back 53

Discovered moons orbiting jupiter. Helped to improve telescopes

Front 54

Kepler

Back 54

The three rules of planetary motion inferred by Johannes Kepler from the data collected by Tycho Brahe.

Front 55

Kepler's First Law

Back 55

planets move in elliptical orbits with the Sun at one focus.

Front 56

Kepler's Second Law

Back 56

a line drawn from the Sun to a planet sweeps out equal areas in equal times as the planet orbits the Sun.

Front 57

Kepler's Third Law

Back 57

the square of the period of a planet’s orbit, measured in years, is equal to the cube of the semimajor axis of the planet’s orbit, measured in astronomical units: (Pyears)2 = (AAU) 3.

Front 58

Newton's First Law

Back 58

an object will remain at rest or will continue moving along a straight line at a constant speed until an unbalanced force acts on it.

Front 59

Newton's Second Law

Back 59

if an unbalanced force acts on a body, the body will have an acceleration proportional to the unbalanced force and inversely proportional to the object’s mass: a = F/m.

Front 60

Newton's Third Law

Back 60

for every force there is an equal force in the opposite direction.

Front 61

Speed

Back 61

The rate of change of an object’s position with time, without regard to the direction of movement.

Front 62

Velocity

Back 62

The rate and direction of change of an object’s position with time.

Front 63

Acceleration

Back 63

The rate at which the speed and/or direction of an object’s motion is changing.

Front 64

Mass vs Weight

Back 64

Mass is intrinsic, the amount of matter a thing has. Weight is dependent upon the force of gravity on that mass.

Front 65

Momentum

Back 65

The product of the mass and velocity of a particle.

Front 66

Angular Momentum

Back 66

A conserved property of a rotating or revolving system whose value depends on the velocity and distribution of the system’s mass.

Front 67

Inverse Square Law

Back 67

The rule stating that a quantity or effect diminishes with the square of the distance from the source. (applies to gravity and light)

Front 68

Escape Velocity

Back 68

The minimum velocity needed for an object to achieve a parabolic trajectory and thus permanently leave the gravitational grasp of another mass.

Front 69

Temperature

Back 69

A measure of the average kinetic energy of the atoms or molecules in a gas, solid, or liquid.

Front 70

Fahrenheit

Back 70

The arbitrary temperature scale that defines 32° as the melting point of water and 212°Fas the boiling point of water at sea level.

Front 71

Celsius

Back 71

The arbitrary temperature scale,that defines 0° as the freezing point of water and 100° as the boiling point of water at sea level.

Front 72

Kelvin

Back 72

The temperature scale, that uses Celsius- sized degrees, but defines 0 as absolute zero instead of as the melting point of water.

Front 73

Absolute Zero

Back 73

The temperature at which thermal motions cease. The lowest possible temperature. Zero on the Kelvin tempera- ture scale.

Front 74

Gravitational Potential Energy

Back 74

The stored energy in an object that is due solely to its position within a gravitational field.

Front 75

Free Fall

Back 75

The motion of an object when the only force acting on it is gravity.

Front 76

Center of Mass

Back 76

1. The weighted average location of all the mass in a system of objects. The point in any isolated system that moves according to Newton’s first law of motion. 2. In a binary star system, the point between the two stars that is the focus of both their elliptical orbits.

Front 77

Tides

Back 77

Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the Moon and the Sun and the rotation of the Earth.

Front 78

Tidal Forces

Back 78

The earth is pushed and pulled by the sun's gravity and the tides respond to it because they are the most flexible.

Front 79

Gravitationally Bound Orbits

Back 79

Objects held in orbit about each other by their gravitational attraction.

Front 80

Waves
(wavelength vs frequency vs energy)

Back 80

Wavelength is inversely proportional to frequency and the smaller the wavelength, the higher the energy. Red is longer, violet is shorter.

Front 81

Speed of Light

Back 81

Almost 3 million meters per second.

Front 82

Electromagnetic Spectrum

Back 82

The spectrum made up of all possible frequencies or wave-lengths of electromagnetic radiation, ranging from gamma rays through radio waves and including the portion our eyes can use.

Front 83

Photons

Back 83

A discrete unit or particle of electromagnetic radiation. The energy of a photon is equal to Planck’s constant (h) multiplied by the frequency (f ) of its electromagnetic radiation.

Front 84

Black Body Radiation

Back 84

electromagnetic radiation within or surrounding a body in thermodynamic equilibrium with its environment, or emitted by a black body held at constant, uniform temperature. The radiation has a specific spectrum and intensity that depends only on the temperature of the body.

Front 85

Spectra

Back 85

Waves sorted by wavelength

Front 86

Continuous Spectrum

Back 86

A spectra without any disruptions, all colors coming in equally.

Front 87

Emission Spectrum

Back 87

A spectra of emission lines. A peak in the intensity of a spectrum that is due to the emission of electromagnetic radiation at a specific wavelength determined by the energy levels of an atom or molecule.

Front 88

Absorption Spectrum

Back 88

A spectra of absorption lines. A minimum in the intensity of a spectrum that is due to the absorption of electromagnetic radiation at a specific wave- length determined by the energy levels of an atom or molecule

Front 89

Atomic Number vs Atomic Weight

Back 89

Number: the number of protons in the nucleus of an atom, which determines the chemical properties of an element and its place in the periodic table.
Weight: the mass of a single atom.

Front 90

Isotopes

Back 90

Forms of the same element that have different numbers of neutrons.

Front 91

Protons

Back 91

A subatomic particle hav- ing a positive electric charge of 1.6 × 10-19 coulomb (C), a rest mass of 1.67 × 10-27 kilo- gram (kg), and a rest energy of 1.5 × 10-10 joule (J).

Front 92

Neutrons

Back 92

A subatomic particle having no net electric charge, and a rest mass and rest energy nearly equal to that of the proton.

Front 93

Electrons

Back 93

A subatomic particle having a negative electric charge of 1.6 × 10-19 coulomb (C), a rest mass of 9.1 × 10-31 kilogram (kg), and rest energy of 8 × 10-14 joule (J).

Front 94

Quanized in Quantum Mechanics

Back 94

Existing as discrete, irreducible units.

Front 95

Doppler Shift

Back 95

The change in wavelength of sound or light that is due to the relative motion of the source toward or away from the observer, amount by which the wavelength of light is shifted. Toward you = shorter = bluer, away = longer = redder.

Front 96

Opaque

Back 96

A measure of how effectively a material blocks the radiation going through it.

Front 97

Transparent

Back 97

Has to do with the ability to see dim objects through the atmosphere.

Front 98

Reflect

Back 98

Light beam directly back out as it was when it hit an object.

Front 99

Scatter

Back 99

Light beam "scattered" or spread apart it comes off an object it is "reflecting" off of.

Front 100

Absorb

Back 100

The process by which an atom captures energy from a passing photon.

Front 101

Emit

Back 101

The production of a photon when an atom decays to a lower energy state.

Front 102

Ionization

Back 102

The process by which electrons are stripped free from an atom or molecule, resulting in free electrons and a positively charged atom or molecule.

Front 103

"Excited" Atroms

Back 103

Any energy level of a system or part of a system, such as an atom, molecule, or particle, that is higher than its ground state.

Front 104

Electron Shells

Back 104

Levels to which electrons jump. An orbit followed by electrons around an atom's nucleus.

Front 105

Thermal Radiation

Back 105

Electromagnetic radiation resulting from the random motion of the charged particles in every substance.

Front 106

Luminosity

Back 106

Intrinsic. The total amount of light emit- ted by an object.

Front 107

Flux

Back 107

The total amount of energy passing through each square meter of a surface each second.

Front 108

Brightness

Back 108

The apparent intensity of light from a luminous object. Brightness depends on both the luminosity of a source and its distance.

Front 109

Why is the sky blue?

Back 109

Blue light scatters more easily coming directly from the sun, hitting off of particles in the air and giving more blue particles to your eyes.

Front 110

Why are sunsets red?

Back 110

Red light scatters more easily at the angle of a sunset through the atmosphere.

Front 111

How far does each part of the electromagnetic spectrum penetrate the atmosphere?

Back 111

Radio - fully
Infrared - partially, gets farther
Visible - fully
UV - partially, goes shallower
XRay - none
Gamma - none

Front 112

Resolution

Back 112

The ability of a telescope to separate two point sources of light. Resolution is determined by the telescope’s aperture and the wavelength of light it receives.

Front 113

Atmospheric Seeing

Back 113

A measurement of the degree to which Earth’s atmosphere degrades the resolution of a telescope’s view of astronomical objects.

Front 114

CCD

Back 114

Charge-coupled device. A common type of solid-state detector of electromagnetic radiation that transforms the intensity of light directly into electric signals.

Front 115

Atmospheric Window

Back 115

A region of the electromagnetic spectrum in which radiation is able to penetrate a planet’s atmosphere.

Front 116

Composition of the Sun

Back 116

Hydrogren & Helium

Front 117

Sun's Thermostat

Back 117

(Stars in general) adjust

Front 118

HR Diagram

Back 118

A plot of the luminosities versus the surface temperatures of stars. The evolving properties of stars are plotted as tracks across the H-R diagram.
http://upload.wikimedia.org/wikipedia/commons/1/17/Hertzsprung-Russel_StarData.png

Front 119

Mass vs Lifetime

Back 119

The smaller the mass of a star the higher the lifetime.

Front 120

Habitable Zones

Back 120

The distance from its star a planet can be in order to have a temperature suitable for liquid water.

Front 121

Hydrostatic Equilibrium

Back 121

In the formation of stars, the equilibrium of gravity pushing out and thermal outward pressure.

Front 122

Fusion vs Fission

Back 122

Fusion - hydrogen combining to helium.
Fission - helium separating to hydrogen.

Front 123

Proton-Proton Chain

Back 123

One of the ways in which hydrogen burning can take place. This is the most important path for hydro- gen burning in low-mass stars such as the Sun
http://www.lucyconklin.com/wp-content/uploads/2012/05/protonproton_conklin.jpg

Front 124

Importance of Neutrinos

Back 124

Science can't identify their small amount of mass. 3 separate types and can change between then randomly. (Electron/Muon/Tau)

Front 125

Solar Wind

Back 125

The stream of charged particles emitted by the Sun that flows at high speeds through interplanetary space.

Front 126

Interstellar Wind

Back 126

The Interstellar Wind, as one might imagine, is the stream of charged particles entering our solar system from somewhere else.

Front 127

Sunspots

Back 127

A cooler, transitory region on the solar surface produced when loops of magnetic flux break through the surface of the Sun. 11 year cycle curing which sunspot activity increases then decreases.

Front 128

Solar Prominences

Back 128

An archlike projection above the solar photosphere often associated with a sunspot.

Front 129

Solar Flares

Back 129

An explosion on the Sun’s surface associated with a complex sunspot group and a strong magnetic field

Front 130

What makes a star "alive."

Back 130

Hydrostatic Equilibrium and Fusion

Front 131

Stellar Classification

Back 131

O B A F G K M
x-axis of HR diagram

Front 132

Class O stars

Back 132

Hot and Luminous
Ultraviolet
Rarest
Dominant Absorption Lines
Burn out Quickly

Front 133

Class B stars

Back 133

Luminous and Blue
Shortlived

Front 134

Class A stars

Back 134

White/Bluish
Strong Hydrogren Lines

Front 135

Class F stars

Back 135

Weaker hydrogen and ionized metals
White

Front 136

Class G stars

Back 136

OUR SUN IS THIS CLASS
Weak hydrogen lines
Ionized and Neutral metals

Front 137

Class K stars

Back 137

Orangish
Cooler
Extremely weak hydrogen lines
Mostly neutral metals

Front 138

Class M stars

Back 138

Most common
Low luminosity
Absent Hydrogren Lines

Front 139

Tycho

Back 139

The motion of the planet Mars enabled Kepler to discover the laws of planetary motion, which provided powerful support for the Copernican heliocentric theory of the solar system.

Front 140

Lunar eclipse

Back 140

Earth comes between the moon and the sun.
Penumbral - in the side shadow
Partial - blocked partially
Total - through the entire umbra

Front 141

Chromosphere

Back 141

Between photosphere and corona

Front 142

Corona

Back 142

Hot, outermost part of the Sun.

Front 143

Photosphere

Back 143

The apparent surface of the Sun as seen in visible light.

Front 144

Cosmic Address

Back 144

System,
Galaxy,
Group,
Cluster, (Supercluster)
Universe,
Smart
Girls
Gulp
Cum
Unintentionally