Earth/
Moon / Tides Notes
Earth
Shape-
imperfect sphere- bulges at equator and is somewhat flattened
at
poles
Axis-
imaginary line that runs through the center that the earth
turns
on
Rotation-
earth spins on axis 1 time/24hrs (23hrs 56min)
Half of earth experiences day & half
night
Revolution-
earth travels around sun 1 time / 365 1/4 days (leap
year-
Feb 29)
Tilted-
23.5 ° angle from 90 °
orbit
Satellite-
body that rotates around another -earth is a satellite of
the
sun & moon is a satellite of the earth ( artificial
satellites
- phone-TV)
Seasons (Caused by tilt, length of day, angle
of sun’s rays)
Travels
in an Ellipse (Circle)
closest
to the sun in Jan 3-147 million km & furthest in July
4 -152 million km
Zenith-
highest point in the sky of the sun- most direct rays hit the
earth at noon
(Most concentrated heat- 90˚ best)
Equinox-
Sun directly hits the equator - Autumnal & Vernal (fall &
spring - March
20-1 & Sept 22-3) Number of hours of day = night
Solstice-
sun directly over the Tropic of Cancer or Capricorn (23.5 °
N & S) (winter & summer - June 21-2 or Dec 21-2)
Longest or
shortest day of
the year – daylight hours are longer for
hemisphere tilted
toward sun
Rotates around
& revolves around the earth at about the same speed –
in 27.3 days -
always see the same side of the moon
Orbit tilted at 5°
angle
Phases- 29.5 days
to complete - Reflects light from sun & as moon
revolves around earth, you see different
portions of its
lighted side which causes its appearances to
change
New moon- far
side lit - not visible - dark half is facing earth
Waxing crescent-
follows new moon - thin slice visible (starts w/in
24
hours of NM) Starting to see more light on the moon
1st
Quarter- 1 week later - half the lighted side is visible
Waxing Gibbous-
after quarter and before full - more than half and
less than all visible
Full moon- whole
lit side facing earth
Waning gibbous-
getting smaller - less than full and more than half
3rd
Quarter- half visible
Waning crescent-
getting smaller - less than half visible- Starting
to see less light on the moon
Eclipses
Don't
occur each time because of the 5°
tilt of moon's path - it
passes
above or below & distance between must be "just right".
Solar-
moon passes between earth and sun and blocks out light and
casts
a shadow on sun in the day(sun goes through phases like
the
moon) 1 to 11/2 total eclipses occur in a year. During
new moon phase - same place 1 every 450 years. Shadow is only 270 -300km wide
viewed by people in its path *Never look directly at a solar eclipse - eye
damage could result.
Umbra-
small dark cone shaped shadow (eclipse)
Penumbra-
larger lighter shadow
Partial
eclipse- moon only covers part- seen in the penumbra
Annular
Eclipse- the moon appears smaller than the sun, leaving a
bright
ring of sunlight visible
Total-
the moon covers the sun precisely or appears same size or
larger
and in perfect alignment
Shadows
contact:
First contact- the moment the moon begins
to cover the sun
Second contact- the moment the moon covers
the sun, thin
crescent
is seen
Third contact- the moment when the moon
begins to uncover sun
Fourth contact- the moment when the moon
moves off the sun
completely
Lunar
- moon passes with in the earths umbra shadow in the night & is
viewed
by most people on night time side of earth During full
moon
phase. 2 to 3 eclipses a year
Tides
Waves- rhythmic movement that carries energy through matter or
space
Parts: crest - top
trough- bottom
wavelength- crest to crest or trough to trough
amplitude- center to crest or trough
wave height- crest to trough
Wave formation: Wind, Earthquakes, or other disturbances
Tides- slow moving water waves with long wavelengths- produce an
alternate rise and fall of surface level of oceans (1-2m high wave that is
thousands of km long)
High tide- highest level that ocean water reaches on the shore
Low tide- lowest level that ocean water reaches on the shore
Daily tide Patterns (repeat every 24 hrs 50 min)
Every coastal area has at
least 1 high & 1 low tide every day
Semidiurnal tides- 2 high & 2 low/day
Diurnal tides- 1 high and 1 low/day
Mixed tides-
Tidal range- difference in level of ocean between high and low
tide
HT - LT = 1.4 - 0.5 =
0.9 tidal range
Highest Spring Tides - Moon and Sun on same side, with combined
gravitational pull producing the highest tides. High tides on
the opposite side are due to the centrifugal force of the Earth's
rotation
Neap Tides - Moon is at a 90° to the Sun, at an angle the
gravitational pull is divided producing lower high tides and a
smaller tidal range
Spring Tides - Moon and Sun are in a line on the opposite sides,
with
combined gravitational pull high tide is higher than neap but
not as high as highest spring tide