chap 29 Flashcards
sphere
a round, three-dimensional object
ellipse
an elongated, close curve with two foci.
is the Earth a perfect sphere?
No
what are some ancient observations that prove Earth is a sphere?
objects fall straight down, the shadow of Earth on the moon, every continent sees different stars
what are two things that effect gravitational forces?
the masses of each object and the distance between them
which diameter of Earth is longest
equator
what does the magnetic do for Earth?
it protects us from harmful radiation from the sun
which magnetic pole is in the northern hemisphere
south magnetic pole
can these magnetic poles flip?
yes, they occur every 200,000 years
what degrees is Earth’s axis tilted?
11.7 degrees
what is the flipping of the south and north magnetic pull called?
magnetic reversal
when was the last magnetic reversal?
780,000 years ago
what is a magnetosphere?
an area within Earth’s magnetic field
how are the auroras created?
when electrically charged particles collide with atom sin the atmosphere and emit light.
what is the scientific name of the northern lights ?
aurora borealis
what is the scientific name of the southern lights?
aurora australis
when is earth closest to the sun
early january - about 147 million km away
when is the earth farthest from the sun?
early july - 152 million km away
time zone
an area 15 degrees wide in which the time is the same
rotation
the spinning of Earth on its axis
revolution
the motion of Earth in an elliptical orbit around the sun
ecliptic
the plane of Earth’s orbit around the sun
solstice
when Earth’s rotational axis is tilted directly towards the sun or away from the sun
equinox
Earth’s rotational axis perpendicular to a line drawn from the center of Earth to the center of the sun
Who devised a method of timekeeping around 3000 B.C.?
Babylonians
What was the symbol for degree taken from?
360 degrees
How many hours does it take the earth to make one full rotation?
24 hours
How many degrees does the earth spin in one hour?
15 degrees
What direction does the sun rise?
East
What direction does the sun set?
West
True or false. All time zones are the exact same size?
False, they are modified to fit around cities, states, and country borders, and other key sites.
How many time zones are there in the world?
24 time zones
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?
6 time zones
What are the names of the time zones?
Mountain time zone Eastern time zone Pacific time zone Alaskan time zone Central time zone Hawaiian time zone
What is a solar day?
The earth’s rotation from the sun in the sky from noon one day to noon the next day.
What is a sidereal day?
When a certain star rises above the horizon until that same star rises again
What are the two main reasons for seasons?
The axis tilt and how close earth is to the sun
Which 2 seasons have a solstice?
Summer and Winter
Which month is the summer solstice?
June
Which month is the winter solstice?
December
Which two seasons are equinoxes?
Spring and Fall
Which month is the spring equinox?
March
Which month is the fall equinox?
September
When is the longest day of the year?
During the Summer Solstice
When is the shortest day of the year?
During the Winter Solstice
When are the days almost 12 hours of day and 12 hours of night?
During the spring equinox and during the fall equinox
tide
a rise or a fall in the ocean surface
moon phase
reflects the change in appearance of the moon as seen from earth
solar eclipse
when the moon moves directly between the sun and earth and casts a shadow on Earth
lunar eclipse
when earth passes between the sun and the moon and casts a shadow on the moon
maria
the dark-colored, flat, lava filled, regions on the moon’s surface
regolith
a layer of dusty lunar material produced by collisions between asteroids and comets and the moon
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?
synodic month
Do we ever see the back side of the moon?
no
What causes a tide to rise or fall?
the gravitational pulls of the sun and the moon
what is the rise of the sea level called?
a high tide
after the sea level rises how many hours does it take for the sea level drop?
about 6 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?
the sun the earth and the moon are in a straight line
how are the sun, the earth, and the moon aligned for a neap tide?
at a 90 degree angle
what does the phase of the moon you see depend on?
position of the moon. earth. and the sun relative to one another
when does a new moon occur?
when the moon is between earth and the sun
how many phases of the moon are there?
8 phases
what is the definition of waxing phases?
the illuminated portion that we see appears larger each night
What is the definition of waning phases?
after a full moon,
what are the moon phase names?
new, waxing crescent, 1st quarter, waxing gibbous, full, waning gibbous, 3rd quarter, waning crescent
where is the word month derived from?
the root word moon
how is the earth,moon and sun aligned during a solar eclipse?
the moon gets between the earth and the sun
what is an umbra?
the darkest portion of the moon’s shadow
what is a penumbra?
how is the earth,moon and sun aligned during a lunar eclipse?
sun earth moon
how are the depressions on the moon formed?
meteorites, asteroids, and comets
are there mountains on the moon?
which side of the moon is thicker?
the dark side
is the mantle of the moon a solid or a liquid?
solid
what did the clementine spacecraft do ?
confirmed that the crust on the side facing earth is much thinner than on the far side
what did the lunar prospector do ?
took photographs of the moon’s surface
what is the giant impact theory?
