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Chapter 1-2
The Earth in Space
Exploring Our World
Pg 29
The Solar System
- sun, planets and other small bodies
- diagram pg 30
- solar system
- Each planet has an orbit
o Path around the sun
o Each planet revolves around the
sun at a different rate
 Earth 365 ¼ days = 1 year
 Mercury 88 days = 1 year
 Pluto 250 years = 1 year
 age/weight
o Two classifications of planets
 Earth, Mercury, Venus, Mars,
PlutoPluto Not a Planet,
Astronomers Rule
 Solid and small
 Few or no moons
 Rotate (spin) slowly
 Jupiter, Saturn, Neptune,
Uranus
 Huge planets
o Uranus
 Smallest of the big
planets
 15 times larger
than earth
 More like balls of gas that
rockier Earthlike planets
 Rotate (spin) rapidly
 Have many moons
 Surrounded by rings made
of bits of rock and dust
Sun, Earth and Moon
- Earth is 93 million miles from the sun
on average
- Earth’s most important companion in
space
o 91 million miles during our
summer
o 94 ½ million miles during our
winter
- Sun temp – 27 million degrees
Fahrenheit
o Necessary for life on earth
Layers of the earth
- atmosphere
o layer of air surrounding the earth
o 1000 miles thick
 99% made up of nitrogen and
oxygen
- Joseph Kittinger
- Highest Parachute Jump Planned
- acts as a greenhouse
o holds in some of the sun’s energy
 w/o this protection the earth
would be too cold for life
o also reflects some of the sun’s
energy back into space
 keeps the earth from becoming
too hot
o shields living things from harmful
rays
Terminology
The troposphere, closest to the Earth, extends to about 6 to 17 km
above the Earth's surface.
The stratosphere lies above the troposphere to about 50 km.
Moon
- earth’s nearest neighbor
o orbits the earth once every 30 days
o cold rocky sphere
o has no water
o has no atmosphere
o gives of no light
 moon shine
 reflection of the sun’s rays
off the moons surface.
Earth’s Movement
- Earth rotates (spins) on its axis
o Imaginary line that runs through
the center of the earth from the
north to the south pole
o Rotation takes 24 hours (23 hours
56 minutes,4.09 seconds) = one
day
 Causes day and night
o Revolution (earth’s complete trip
around the sun) takes 365 ¼ days =
1 year (365 days 6 hours, 9
minutes, 9.54 seconds)
 ¼ of a day is made up every 4
years by adding a day to the
month of February – Leap Year
 earth facts
The Sun and the Seasons
Page 31
Cause of Seasons
- The tilt of the earth at 23 ½ ° is the
cause of the different seasons
- The tilt of the earth is responsible for
the northern and southern hemispheres
having their season “opposite” of each
other.
- When the sun’s rays are more direct
the hemisphere experiences summer
- When the sun’s rays are not direct the
hemisphere experiences winter
Solstices and Equinoxes
June 21
- Summer Solstice in the northern
hemisphere
- Winter solstice in the southern
hemisphere
- North pole is tilted toward the sun
- First day of summer in the northern
hemisphere
- Sun is located directly above the
Tropic of Cancer – 23 ½ ° North
Latitude
- On this day the northern hemisphere
has the longest amount of daylight and
the shortest amount of darkness
- On this day the northern hemisphere
has the shortest amount of daylight and
the longest amount of darkness.
December 21-22
- Winter Solstisce
- North Pole is tilted away from the sun
- First day of winter in the northern
hemisphere
- Sun is located directly above the
Tropic of Capricorn – 23 ½ ° South
Latitude.
- Longest amount of daylight in the S.
Hemisphere
- Shortest amount of daylight in the N.
Hemisphere.
Equinoxes
- Spring – Vernal
- March 21-22 in the Northern
Hemisphere
- Fall – Autumnal
- September 22-23 in the Northern
Hemisphere
- On this day the sun is located directly
over the equator.
- Most places on the earth have close to
12 hours of daylight and 12 hours of
darkness.
- Sunrise, Sunset & Twilight For Cities
Chapter 1-2 Assessment – pg 32