Astronomy Exam 1

Front 1

Vector

Back 1

A quantity having direction as well as magnitude. Velocity is a vector quantity, it gives both speed and direction. Acceleration is also a vector quantity, gives the rate of change of a body's velocity.

Front 2

Scalar

Back 2

(Of a quantity) having only magnitude, not direction. Speed is a scalar quantity, it only tells you how fast something is going, not the direction.

Front 3

Linear Momentum

Back 3

Linear MomentumProduct of a body’s mass times that body’s velocity.A body at rest has zero linear momentum.

Front 4

Angular Momentum

Back 4

Angular Momentum is the product of mass x velocity x the radius of an orbit, or angular momentum = mvr, where m=mass, v=velocity r=radius.

Since angular momentum is conserved, and if mass is constant, then lowering the radius will increase the velocity. Things in smaller orbits go faster.

Front 5

Center of Mass

Back 5

A point representing the average position of the matter in a body or system.

Front 6

Precession

Back 6

The slow, conical motion of the earth's axis of rotation, caused by the gravitational attraction of the sun and moon, and, to a smaller extent, of the planets, on the equatorial bulge of the earth.

Front 7

Refraction

Back 7

The fact or phenomenon of light, radio waves, etc. being deflected in passing obliquely through the interface between one medium and another or through a medium of varying density.

Front 8

Dispersion

Back 8

The phenomenon of splitting of visible light into its component colors is called dispersion. Dispersion of light is caused by the change of speed of light in the medium it passes through.

Front 9

Diffraction

Back 9

Diffraction is defined as the interference or bending of waves around the corners of an obstacle or through an aperture.

Front 10

Interference

Back 10

Interference: when waves interfere with each other

-Constructive interference: When two wave peaks are in exactly the same place, they combineAmplitude is momentarily 2a, a doubled amplitude (a)

-Destructive interference: When a wave peak and a wave valley are in exactly the same place, they combineAmplitude is momentarily reduced

Front 11

Inertia

Back 11

Inertia is the property of an object whereby it tends to maintain whatever velocity it has.

Front 12

Centripetal Force

Back 12

Centripetal (center-seeking) force is the force directed toward the axis of motion, the center of the orbit. Or toward one of the foci in an ellipse.

Front 13

Zenith

Back 13

The point straight above an observer on the Earth's surface is their "zenith".

Front 14

Nadir

Back 14

The point straight below an observer on the Earth's surface is their "nadir".

Front 15

Altitude

Back 15

An object's altitude is the angle between line of sight from the observer to the horizon plane.

Front 16

Azimuth

Back 16

Azimuth is the angle between the north cardinal point on the horizon and and the object, measured in 360 degrees toward the east.

Front 17

Right Ascension

Back 17

The equivalent of longitude in the Celestial Sphere. It only increases eastward, and is measured in unites of time, not degrees. 24 hours = 360 degrees.

Front 18

Declination

Back 18

Equivalent to latitude on the Celestial Sphere. Runs northward and southward from the Celestial Equator.

Front 19

great circle

Back 19

A circle on the surface of a sphere which lies in a plane passing through the sphere's center.

Front 20

small circle

Back 20

A circle formed on the surface of a sphere by the intersection of a plane that does not pass through the center of the sphere.

Front 21

Latitude

Back 21

The angular distance of a place north or south of the earth's equator, usually expressed in degrees and minutes. Negative is south, positive is north.

Front 22

Longitude

Back 22

The angular distance of a place east or west of the Prime Meridian at Greenwich, England, usually expressed in degrees and minutes.

Front 23

Equinoxes

Back 23

The time or date (twice each year) at which the sun crosses the celestial equator, when day and night are of approximately equal length.

Front 24

Black Body Radiators

Back 24

The Perfect Radiator (hypothetical)

-Absorbs all radiation, reflects none

-emit some radiation at all wavelengths

-They’d be dark at room temperature, and so are called black body radiators

Front 25

Excitation

Back 25

The application of energy to a atom, causing an electron to move up to a higher orbit.

Front 26

De-Excitation

Back 26

to cause (an atom) to fall from an excited energy level to a lower energy level.

Front 27

Ionization

Back 27

Ionization, or ionisation is the process by which an atom or a molecule acquires a negative or positive charge by gaining or losing electrons

Front 28

Re-combination

Back 28

This process, in which protons re-capture free electrons and make new neutral atoms, is called recombination

Front 29

Centrifugal force

Back 29

An apparent force that acts outward on a body moving around a center, arising from the body's inertia. Not a real force.

Front 30

Oblateness

Back 30

Oblateness is a measure of the flattening of the Earth’s shape; the Earth is said to be an oblate spheroid

Front 31

The Foucault pendulum

Back 31

The Foucault pendulum or Foucault's pendulum is a simple device named after French physicist Léon Foucault, conceived as an experiment to demonstrate the Earth's rotation. A long and heavy pendulum suspended from the high roof above a circular area was monitored over an extended time period, showing that the plane of oscillation rotated.

Front 32

The Fahrenheit Temperature Scale

Back 32

Fahrenheit is a scale for measuring temperature, in which water freezes at 32 degrees and boils at 212 degrees.

Front 33

The Centigrade Temperature Scale

Back 33

Celsius is a scale for measuring temperature, in which water freezes at 0 degrees and boils at 100 degrees.

Front 34

The Kelvin or Absolute Temperature Scale

Back 34

Kelvin is a scale for measuring temperature, in which 0 is absolute zero, water freezes at 273.15 K, and water boils at 373.15 .

Front 35

Solstices

Back 35

The time or date (twice each year) at which the sun reaches its maximum or minimum declination, marked by the longest and shortest days.

Front 36

Celestial sphere

Back 36

Stars appear to be fixed on the inside of an immense, hollow bowl centered on the observer. It appears to rotate on "celestial poles", lines intersecting the Earth and the sphere at the geographic poles.

Front 37

Celestial equator

Back 37

Passes through the Earth's equator in a plane, which is a great circle.

Front 38

Local celestial meridian

Back 38

The Local Meridian is an imaginary Great Circle on the Celestial Sphere that is perpendicular to the local Horizon.

Front 39

Four cardinal points

Back 39

North, South, East and West on the observer's horizon.

Front 40

Perihelion

Back 40

the point in the orbit of a planet, asteroid, or comet at which it is closest to the sun.

Front 41

Aphelion

Back 41

The point in the orbit of a planet, asteroid, or comet at which it is furthest from the sun.

Front 42

Perigee

Back 42

The point in the orbit of a satellite at which it is closest to the Earth.

Front 43

Apogee

Back 43

The point in the orbit of a satellite at which it is furthest to the Earth.

Front 44

Semi-major axis

Back 44

Half of the major axis, runs through the two foci of the ellipse.

Front 45

Semi-minor axis

Back 45

Half of the minor axis, runs normal to the major axis of an ellipse.

Front 46

Focal distance

Back 46

The distance of the foci from the center of an ellipse.

Front 47

Eccentricity

Back 47

Eccentricity is the ratio of the focal distance over the semi-major axis of an ellipse.

Front 48

Inferior planets

Back 48

Mercury, Venus

Front 49

Superior planets

Back 49

Mars, Jupiter, Saturn, Uranus, Neptune (Earth?)

Front 50

Planetary configurations

Back 50

The apparent position of a planet in the sky in relation to its actual position in the solar system with reference to the earth and the sun.

Front 51

Elongation angle

Back 51

The elongation is the angular separation between the Sun and a planet or other Solar System body as observed from the Earth.

Front 52

Synodic period

Back 52

The synodic period, the time required for a body within the solar system, such as a planet, the Moon, or an artificial Earth satellite, to return to the same or approximately the same position relative to the Sun as seen by an observer on the Earth.

Front 53

Sidereal period

Back 53

The period of revolution of one body around another with respect to the distant stars.

Front 54

Obliquity of the ecliptic

Back 54

The "obliquity of the ecliptic" describes the 23 1/2 degree tilt of the Earth's spin axis in relation to the normal of the ecliptic plane.

Front 55

The zodiac

Back 55

The zodiac (means "circle of animals" is a band in the sky that contains the constellations through which the Sun appears to move during each year. It includes 13 constellations, not 12.

Front 56

Tides (including spring and neap tides)

Back 56

Tides are caused by the gravitational attraction of the Moon, causing the Earth to flow toward it on the near side and the far side.

-A spring tide is the greatest difference between high and low tide during a given day. Such tides occur about twice a month when the lunar and solar tides correspond.

-A neap tide is the smallest difference between high and low tide in a single day, when the solar tide almost cancels the Lunar tide.

Front 57

Tidal friction

Back 57

Tidal friction is friction created by the tides. The Earth’s rotational motion tends to drag the tides along with it, so that the high tide is not located directly underneath the Moon, but is instead located slightly farther to the east of the line from the Earth to the Moon.

Front 58

Ecliptic

Back 58

The apparent path of the Sun in the sky is called the ecliptic. Not the same as the ecliptic plane.

Front 59

Ecliptic plane

Back 59

The ecliptic or ecliptic plane is the orbital plane of Earth around the Sun.

Front 60

Horizon

Back 60

The plane extending straight out around an observer on the Earth's surface.

Front 61

Horizon plane

Back 61

Imaginary plane that passes through the center of the Earth, perpendicular to the radius of the Earth

Front 62

The Epicycle

Back 62

A. small circle whose center moves around the circumference of a larger one. Used to describe planetary orbits in the Ptolemaic system.

Front 63

The Deferent

Front 64

The Equant

Back 64

(in the Ptolemaic system) an imaginary circle introduced with the purpose of reconciling the planetary movements with the hypothesis of uniform circular motion.

Front 65

Stellar Parallax

Back 65

Stellar parallax, is the apparent shift of position (parallax) of any nearby star (or other object) against the background of distant stars. Was not measured until 1838, because it is so small.

Front 66

The Geocentric Model

Back 66

A scientific model of the universe that places the Earth at the center of everything.

Front 67

The Heliocentric Model

Back 67

A scientific model of the universe that places the Sun at the center of the Solar System.

Front 68

Diurnal motion

Back 68

The rotation of the Earth toward the east makes the celestial sphere appear to rotate toward the west every day. This is called "diurnal motion".

Front 69

Annual motion

Back 69

The eastward motion of the Sun along the ecliptic is called its annual motion.

Front 70

Retrograde motion

Back 70

Retrograde motion, in astronomy, actual or apparent motion of a body in a direction opposite to that of the (direct) motions of most members of the solar system.

Front 71

Kepler’s 3 Laws of Planetary Motion

Back 71

1. Each orbit is an ellipse. The Sun is at one foci, the other is empty.

2. A planet moves along its elliptical path with a speed that changes in such a way that the line from the planet to the sun sweeps out equal areas in equal intervals of times.

3. (1618) The ratio of the cube of a planet's average distance (a) from the sun to the square of its orbital period (p) is the same for each planet (a cubed / p squared = C). This was wrong, it varies slightly for each planet according to Newton.

Front 72

Newton’s 3 Laws of Physics

Back 72

1. first law, an object will not change its motion unless a force acts on it.

2. second law, the force on an object is equal to its mass times its acceleration.

3. third law, when two objects interact, they apply forces to each other of equal magnitude and opposite direction.

Front 73

Newton’s Law of Gravitation

Back 73

This law states that between every two objects there is an attractive force, the magnitude of which is directly proportional to the mass of each object and inversely proportional to the square of the distance between the centers of the objects

-In equation form: F=GM⌄1M⌄(2) / d^2

-G is the universal constant of Gravitation

-M are the masses

-D is the distance

-Minus sign means its an attractive force

Front 74

Wien’s Law

Back 74

Black body radiation has different peaks of temperature at wavelengths that are inversely proportional to temperature. (As the temperature of a black body is increased, the wavelength of its peak emission is decreased.)

𝛌⌄peak T = constant, where T is the temperature in degrees in Kelvin.

Front 75

Stefan-Boltzmann Law

Back 75

Tells us how much energy a black body of a given temperature will give off every second from each small area of its surface. E = 𝛔T^4.

Even a small increase in temperature (T) raises the energy output dramatically.

Front 76

Planck’s Law

Back 76

The formula which gives the shape of the black body energy spectra. All you need to know before hand is the temperature, and you can figure out the energy being emitted at each wavelength

Front 77

Kerchhoff’s 3 Rules of Spectral Analysis, including the different Effects: The Photoelectric Effect, The Coriolis Effect, The Principles included the Heisenberg Uncertainty Principle

Back 77

1st Rule: A hot, dense, glowing object (hot solid, a hot liquid, or a hot, high-density gas) will emit a continuous, black body type specturm

2nd Rule: A hot, low-density gas will emit light only certain wavelengths, - a bright line, or an emission line spectrum

3rd Rule: When light having a continuous spectrum passes through a cooler gas, dark lines appear superimposed upon the continuous spectrum

Front 78

The Photoelectric Effect

Back 78

Certain metals, when illuminated with a beam of light at high frequency, would emit individual electrons.

Einstein explained the Photoelectric Effect by suggesting that all electromagnetic radiation, and not just that from black bodies, travels as quanta

Front 79

The Coriolis Effect

Back 79

In physics, the Coriolis force is an inertial or fictitious force that acts on objects in motion within a frame of reference that rotates with respect to an inertial frame. In a reference frame with clockwise rotation, the force acts to the left of the motion of the object

Front 80

The Heisenberg Uncertainty Principle

Back 80

The position and momentum of an electron cannot be determined simultaneously with absolute accuracy.