Transcript Days, Years, and Seasons

SOLAR SYSTEM
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Sun is at the center, other objects orbit it
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Sun is a star
Orbit- path an object takes around the sun
8 planets
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Mercury
Venus
Earth
Mars
Jupiter
Saturn
Uranus
Neptune
Pluto
Inner Planets
Outer Planets
SOLAR SYSTEM
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Moons- bodies that orbit planets
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Earth has one moon
Jupiter and Saturn
have many moons
Mercury and Venus-no
moons
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Asteroid- small rocky bodies that revolve around the sun,
most found in asteroid belt
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Comet- made up of ice, dust and small gritty particles, have
“tail”, many come from Oort cloud, beyond Pluto
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Meteroid- small particles of rock, most come from asteroids
or comets, produce streaks of light called meteors, when
they land on Earth they are called meteorites
SOLAR SYSTEM REVIEW
1.) Which statement best describes how the sun and Earth are related?
a. Earth revolves around the sun
b. The sun revolves around the Earth
c. Earth rotates around the sun
d. The sun rotates around Earth
2.) Which list gives the inner planets in correct order starting with the planet closest to the sun?
a. Mercury, Earth, Venus, Mars
b. Venus, Earth, Mars, Mercury
c. Mercury, Venus, Earth, Mars
d. Mars, Venus, Earth, Mercury
3.) Which of the following is a rock from space that lands on Earth?
a. Meteoroid
c. comet
b. asteroid
d. meteorite
4.) Which of these does NOT describe an outer planet?
a. rocky
c. has many moons
b. has rings
d. gasous
THE SUN AND OTHER STARS
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Star- a sphere of hot glowing gases that gives off its own
light and is held together by gravity
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Sun =Medium star by size and mass, yellow in color, surface
temp 5,500oC, diameter 1.4 million kilometers, mass 1.99 x
1030 kg
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Sun- contains 99.8% of the mass of our solar system,
the sun is a star, made of mostly hydrogen gas
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Nuclear Fusion- process that provides sun’s energy
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In nuclear fusion, two atoms of hydrogen combine to form
helium producing extreme amounts of energy
THE SUN AND OTHER STARS
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Temperature of a star determines its color
Color
Temperature
30,000oC
9,500oC
6,000oC
5,000oC
3,000oC
Brightness determined by size and temperature
 Absolute magnitude- describes actual brightness if
it were a standard distance from Earth, measured
from -10 to +15 (negative=brighter)
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THE SUN AND OTHER STARS
HR Diagram
 Most stars fall with in
diagonal band of stars
called main sequence.
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These stars show a
direct relationship
between temperature and
brightness
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Hotter stars burn
brighter.
Cool red giants in the
upper right are bright because
of their size
Hot white dwarfs are
dim because they are so
small
THE SUN AND OTHER STARS
Life Cycles of Stars
Stars form when clouds of gas become compressed enough to start the process of nuclear fusion,
**Its mass determines its life cycle
Most stars enter the main sequence phase
1.
*lasts about 10 billion years,
nuclear fusion powers these
stars
**HOT STARS USE OF THEIR
HYDROGEN FASTER THAN COOL
STARS
Stars leave main sequence
2.
a)
Low mass left—collapse and
become white dwarf
a)
Medium mass- enters period of
expansion and contraction, use
helium as fuel, becomes red giant,
after about a billion years collapses
to white dwarf, then cools to black dwarf
a)
Very Massive- become super giant
(huge, cool, red stars), helium and carbon
used as fuel, if massive enough will
collapse to neutron star when it dies,
most massive collapse into black holes
(an object so dense light cannot escape
from it)
Sun
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main sequence star
about 4.6 billion years old,
will burn hydrogen for about 5 billion more years
then it will become a red giant and burn helium
when helium runs out fusion will stop
red giant will become white dwarf
the sun will continue to give off energy as it cools into a black dwarf
THE SUN AND OTHER STARS REVIEW
1.) What kind of star is our sun?
a. supergiant
c. white dwarf
b. red giant
d. main sequence
2.) Which of the following is MOST important in determining a
star’s life cycle?
a. its mass
c. its color
b. its diameter
d. its brightness
3.) What fuel does a main-sequence star use for nuclear fusion
a. oxygen
c. helium
b. petroleum
d. hydrogen
DAYS, YEARS, AND SEASONS
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Length of year-time in which a planet completes on orbit around the sun
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365 days
Planets that are farther from the sun have longer years than those closer to the sun
Length of day-time in which a planet makes on full turn on its axis
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24 hours
Length of day varies among the planets
Seasons-variation in length
of day and temperature
based amount of sunlight
received
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Amount of sunlight
affected by tilt of the Earth
on its axis
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Summer Solstice
Autumnal Equinox
Winter Solstice
Vernal Equinox
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**Equinox 
equal
PHASES OF THE MOON
Phases of the moon:
 Same side of moon always faces the Earth
Moon takes the same amount of time to orbit Earth as it
does to turn on its axis
 Moon’s orbit around Earth is
angled so an eclipse does not
occur often
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 At
any time half the moon
is lit, half the time its dark
Waxing- sunlit part of the
moon grows larger
Waning- sunlit part of the
moon grown smaller
TIDES
Tide- rise or fall of surface of water due to gravitational
force
High tide-highest level of water along shore
 Low tide-lowest level of water along shore
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Spring Tide-moon, sun, and earth in line during new
or full moon, greatest difference between high and
low tide
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Neap Tide-moon, sun and earth at right angles during
new or full moon, least differences between high and
low tide
http://oceanservice.noaa.gov/education/tutorial_tides/medi
a/supp_tide06a.html
ECLIPSES
Solar Eclipse-moon blocks sun’s light and casts a
shadow onto Earth
 Only occurs during new moon
 Moon passes between sun and Earth
 Umbra-area
of total eclipse, sky becomes dark as night
 Penumbra-area of partial eclipse, not as dark as
ECLIPSES
Lunar Eclipse-moon passes into Earth’s shadow
 Earth is between sun and moon, this blocks sun’s
light from reaching the moon
 Only occurs during a full moon
Most lunar
eclipses are
partial
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