Chapter 29 Flashcards
a round, three-dimensional object, the surface of which is the same distance from the center in all directions is a called a what?
sphere
an elongated, closed curve with two foci is called a what?
ellipse
is earth a perfect sphere?
no, the diameter is further longways than pole to pole
what are some ancient observations that prove earth is a sphere?
objects always fall straight to the surface, the earth’s shadow of a lunar eclipse is curved, and if earth were flat, everyone would be able to see the same stars
what are two factors that gravitaitonal strength?
mass and distance
what does the magnetic field protect earth from?
harmful radiation from the sun
which hemisphere is the megnetic field located in?
its in the northern hemisphere
at which degrees does earth’s axis tilt?
11.7 degrees
can magnetic poles change?
yes
what is a large scale movement where the magentic poles switch?
magnetic reversals
how often do magnetic reversals occur?
every 200,000 years
which part of earths magnetic field deflects harmful radiation from the sun?
the magnetosphere
what are the two scientific names for the northern and the southern lights?
aurora borealis (northern lights) aurora australis (southern lights)
how are the auroras created?
electrically charged particles collide with atoms in the atmosphere and emit light
when is earth closest to the sun?
early january-147 million km away
when is earth farthest away from the sun?
early july-152 million km away
an area 15 degrees wide in which time is the same is a what?
time zone
the spinning of earth on its axis is called what?
rotation
what is the motion of earth in an elliptical orbit around the sun called?
revolution
the plane of earth’s orbit around the sun is called what?
an eliptic
what occurs when earth’s rotational axis is tilted directly toward the sun or away from the sun?
a solstice
what happens when earth’s rotational axis is perpendicular to a line drawn from the center of earth to the center of the sun?
an eqiunox
who devised a method of timekeeping around 3000 b.c?
the babylonians
what was the sybmbol for degree taken from?
the babylonians symbol for the sun
how many degrees does the earth spin in one day?
360 degrees
how many hours does it take the earth to make one full rotation?
23 hours 56 minutes and 4 seconds
how many degrees does the earth spin in one hour?
15 degrees
what direction does the sun rise?
in the east
what direction does the sun set?
in the west
true or false, all time zones are the exact same size?
false, they are modified to fit ariund cities, states, country borders, and other key sites
how many times zones are there in the world?
24
which direction do you move to add hours to the time?
east
which direction do you move to subtract hours from the time?
west
how many time zones are there in the united states?
six
what are the names of the time zones?
atlantic (alaskan), pacific, mountain, eastern, hawaiian, and central
what is a solar day?
the movement of the sun of one noon of one day to the next noon the next day
what is a sidereal day?
a star being there one day, and it being in the same spot the same time the next day
what are the two main reasons for seasons?
revolution and the tilt of the axis of earth
which two seasons have a solstice?
summer and winter
which month is the summer solstice?
june 21
which month has the winter solstice?
december 21
which two seasons are equinoxes?
spring and fall
which month is the spring equinox?
march 20 or 21
which month is the fall equinox?
september 22 or 23
when is the longest day of the year?
june 21
when is the shortest day of the year?
december 21
when are the days almost 12 hours of day and 12 hours of night?
the equinoxes
a rise or fall in the ocean surface is a what?
a tide
a what reflects the change in appearance of the moon as seen from earth?
a moon phase
what occurs when the moon moves directly between the sun and earth and casts a shadow on earth?
a solar eclipse
what occurs when earth passes between the sun and the moon and casts a shadow on the moon?
a lunar eclipse
what are dark-colored, flat, lava filled regions on the moon’s surface called?
maria
a layer of dusty lunar material produced by colliions between asteroids and comets and the moon are called what?
regolith
how many days does it take the moon to revolve around earth?
27.3 days
a complete lunar phase cycle takes 29.5 days, what is this called?
a synodic month
do we ever see the back side of the moon?
no
what causes a tide to rise or fall?
the gravitaional pull of the sun and moon
what is the rise of sea level called?
a high tide
after the sea level rises how many hours does it take for the sea level to drop?
about six hours
which is farther from earth? the sun or the moon?
the sun
does the moon or the sun cause a greater effect on earth’s tides?
the moon
how are the sun, the earth, and the moon aligned for a spring tide?
in a straight line, sun earth moon
how are the sun, the earth, and the moon, aligned for a neap tide?
it goes over and up, sun, earth, moon
what does the phase of the moon you see depend on?
the positions of the moon, the earth, and the sun relative to eachother
when does a new moon occur?
when the moon is between the earth and sun
how many phases of the moon are there?
eight
what is the definition of waxing phases?
the illuminated portion of the moon that we see appears larger each night
what is the definition of waning phases?
the illuminated portion of the moon becomes smaller each night
what are the moon phase names?
new, waxing crescent, first quarter, waxing gibbous, full, waning gibbous, third quarter, and waning crescent
where is the word month derived from?
the word moon
how is the earth, moon, and sun aligned during a solar eclipse?
the moon is between the sun and the earth; sun, moon, earth
what is an umbra?
the darkest portion of the moon’s shadow
what is a penumbra?
the lighest part of the moon’s shadow
how is the earth, moon, and sun aligned during a lunar eclipse?
the earth is between the sun and the moon; moon, earth, sun
how are the depressions on the moon formed?
asteroids, meteorites, and comets collide with moon’s surface
are there mountains on the moon?
yes
which side of the moon is thicker?
the far side
is the mantle of the moon a solid or a liquid?
a solid
what did the clementime spacecfract do? ( two things)
it confirmed the thickness of the moon’s crust, and also provided information of the mineral content of the moon’s rocks
what did the lunar prospector do? (three things)
it took photos of moon’s surface, confirmed that the moon has a small iron-rich core, and collected evidence that supports the presence of water-ice on the moon
what is the giant impact theory?
a mars-sized object hit earth, sending debris out into orbit, the debris collected and compacted, making the moon
