Planets And Starts Test 1

Front 1

summer solstice

Back 1

Point on the ecliptic farthest north of the celestial equator.

Front 2

equinox

Back 2

Each of the two points where the ecliptic and the celestial equator intersect. Exactly opposite each other on the celestial sphere. When sun is at these points, day and nights are 12 hours long.

Front 3

celestial equator

Back 3

the line that would divide the sky into northern and southern hemispheres and would be created by projecting the Earth's equator into space

Front 4

winter solstice

Back 4

the point where the sun is the farthest south of the celestial equator

Front 5

celestial sphere

Back 5

a large sphere with Earth at its center

it rotated once a day causing the motion of the sky

Front 6

ecliptic

Back 6

the circular path that the Sun appears to trace out against the background of stars

same plane as the ecliptic plane

Front 7

lunar eclipse

Back 7

when the moon passes through the sun's shadow

Front 8

penumbra

Back 8

for lunar eclipses - the darkest part of the shadow where no portion of the sun's surface can be seen

Front 9

umbra

Back 9

for lunar eclipses - can see a portion of the sun's surface

Front 10

solar eclipse

Back 10

when the Earth passes through the Moon's shadow

Front 11

penumbral eclipse

Back 11

Earth blocks up part of Sun's light and so none of the lunar surface is completely shaded, moon looks full, but dimmer

Front 12

total lunar eclipse

Back 12

occurs when the Moon travels completely into the umbra

Front 13

apogee

Back 13

the Moon's farthest position from the Earth

Front 14

perigee

Back 14

the Moon's closest position to the Earth

Front 15

geocentric model

Back 15

a model of the universe with the Earth at the center

Front 16

direct motion

Back 16

eastward progress of planets

Front 17

retrograde motion

Back 17

occasional westward motion of planets

Front 18

Ptolemaic system

Back 18

each planet moved in an epicycle who center in turn moved in a larger circle called a deferent which was centered approximately on the Earth

Front 19

heliocentric model

Back 19

a model where all planets, including Earth, revolved around the Sun

Front 20

synodic period

Back 20

the time that elapses between two successive identical configurations as seen from Earth

Front 21

sidereal period

Back 21

the true orbital period of a planet, the time it takes the planet to complete one full orbit of the Sun relative to the stars

Front 22

parallax

Back 22

a phenomenon where the apparent position of an object changes because of the motion of the observer

Front 23

ellipse

Back 23

a particular kind of curve that describes planet's orbits and is made up of 2 foci and a major axis

Front 24

Kepler's 1st law

Back 24

the orbit of a planet around the sun is an ellipse with the sun at one focus

Front 25

perihelion

Back 25

the point where a planet is nearest to the sun and moves most rapidly

Front 26

aphelion

Back 26

the point where a planet is furthest from the sun and moves most slowly

Front 27

Kepler's 2nd law/law of equal areas

Back 27

a line joining a planet and the Sun sweeps out equal areas in equal intervals of time

Front 28

wavelength

Back 28

distance between two successive wave crests

Front 29

the electromagnetic spectrum

Back 29

from shortest to longest wavelength, gamma rays, x-rays, UV radiation, visible light, infrared radiation, microwaves, radio waves

Front 30

blackbody

Back 30

a perfect blackbody does not reflect any light and instead absorbs all radiation falling on it

Front 31

rule of temperature and radiation

Back 31

the higher an object's temperature, the most intensely the object emirs electromagnetic radiation and the shorter the wavelength at which it emits most strongly

Front 32

photo relations

Back 32

the greater the wavelength, the lower the energy of a photon associated with that wavelength

Front 33

spectral analysis

Back 33

a technique of distinguishing chemical elements by looking at the unique pattern of spectral lines

Front 34

Kirchhoff's law 1

Back 34

a hot opaque body (perfect blackbody) produces a continuous spectrum with no spectral lines

Front 35

Kirchhoff's law 2

Back 35

a hot transparent gas produces an emission line spectrum, which is a series of bright spectral lines against a dark background

Front 36

Kirchhoff's law 3

Back 36

a cool transparent gas in front of a source of a continuous spectrum produces an absorption line spectrum - a series of dark spectral lines among the colors of the continuous spectrum

Front 37

Bohr's model of hydrogen

Back 37

a model of a hydrogen atom with a proton at the middle where an atom must absorb energy for an electron to go from an inner to an outer orbit and an atom must release energy for the electron to go form an outer to an inner orbit

Front 38

ionization

Back 38

the electron in it's ground state and the atom absorbs a photon of energy greater than 13.6 eV, so the electron is completely removed from the atom

Front 39

angular resolution

Back 39

a quantity that gauges how well fine details can be seen, poor AR causes star images to be fuzzy and blurred together

Front 40

chromatic aberration

Back 40

an optical effect where stars viewed through a telescope that uses a simple lens are surrounded by fuzzy, rainbow-colored halos, happens when different colors of light bend at different angles so the colors do not focus at the same point

Front 41

diffraction

Back 41

a limiting factor of angular resolution tha is a tendency of light waves to spread out when they are confined to a small area like the lens of a telescope

Front 42

interferometry

Back 42

two widely separated telescopes that observe the same object simultaneously and then blend the images together

Front 43

Kuiper belt

Back 43

a band that extends from 30 to 50 AU from the sun and is centered on the place of the ecliptic, most trans-neptunian objects orbit in this belt

Front 44

spectroscopy

Back 44

measuring spectra can tell us lots about planets

Front 45

diffraction grating

Back 45

a piece of glass where thousands of regularly spaced parallel lines have been cut and these break up the light from a source into a spectrum

Front 46

average density

Back 46

the mass of a planet divided by volume

Front 47

terrestrial planets

Back 47

made of rocky materials and have dense iron cores which give these planets high densities

Front 48

jovian planets

Back 48

composed primarily of light elements such as hydrogen and helium, which gives these planets low average densities

Front 49

escape speed

Back 49

the minimum speed that an object at a planet's surface must have in order to permanently leave the planet; a planet can retain a gas if the escape speed is at least 6 times greater than the average speed of the molecules in the gas

Front 50

average speed of a gas atom or molecule

Back 50

for a given gas temperature, the greater the mass, the slower its average speed