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Aim: What are Earth’s physical properties?
1. Spherical shape2. Rotates on an axis◦ Rotation of Earth: causes day and night 1rotation= 1 day
3. Magnetic field◦ North and south pole◦ Protects you from harmful solar
radiation by trapping charged particles from the Sun
Magnetic axis is different from its rotational axis Magnetic axis-the line joining the
north and south poles When you follow a compass you are
following the magnetic axis not rotational axis
1revolution=1year◦Earth’s orbit is an ellipse◦Distance from the Earth to the sun changes
◦Earth is closest to the sun in January
◦Earth is farthest from the Sun in July
Earth’s tilted axis causes seasons
The number of daylight hours is greater for the hemisphere that is tilted towards the Sun◦Winter-hemisphere titled away from the Sun
Less sunlight each day◦Summer-hemisphere titled towards the sun
Longer periods of sunlight each day
Earth’s tilt also causes the Sun’s radiation to hit the Earth at different angles
Summer◦the Sun’s radiation strikes at a higher angle causing it to be hot
Winter◦the hemisphere that is not tilted toward the sun, experiences less radiation
The day when the Sun reaches its greatest distance north or south of the equator
Northern Hemisphere◦Summer Solstice occurs on June 21 or 22
Longest day of the year hours of sunlight begin to decrease
◦Winter Solstice occurs on December 21 or 22
Shortest day of the year hours of sunlight begin to increase
Southern Hemisphere◦Winter Solstice is in June◦Summer Solstice is in December
Occurs when the Sun is directly above the equator
Causes fall and spring#of daylight and night time hours are equal
Neither the Northern or Southern Hemisphere is tilted toward the Sun
Northern Hemisphere◦Spring Equinox-March 20 or 21◦Fall Equinox-September 22 or 23
Southern Hemisphere◦Spring Equinox-September◦Fall Equinox- March
Aim: How does the Moon move around the Earth?
Rotates on an axisRevolves around the EarthMoons rotation and revolution both take 27.3 days◦Because of this the same side of the moon always faces Earth
Moon’s surface reflects sunlight◦Half of the moon is lighted, while the other half is dark
The moon’s appearance changes as the Moon revolves around the Earth and you see different portions of its lighted side
Different forms that the moon takes in appearance from Earth
Phase depends on position of the moon, Earth and sun
New moon◦Occurs when the moon is between the
Earth and the sun◦Lighted half of the moon is facing the Sun
and dark side is facing the Earth◦can not be seen◦Rises and sets with the sun
Begins after a new moon Waxing-more of the illuminated half of the
moon can be seen each night Waxing crescent
◦ 24 hrs after a new moon you see a thin slice of the moon
First quarter phase◦ See ¼ of the moon’s surface
Waxing gibbous◦ More than ¼ of the moon is seen
Full moon◦ Occurs when all of the moon’s surface faces
Earth
Happens after a full moon You see less of the moon’s surface Waning gibbous
◦begins just after a full moon Third-quarter phase
◦See only half of the lighted side of the moon
Waning crescent◦Occurs just before a new moon
Takes about 29.5 days for the moon to complete its cycle of phases
Discrepancy between cycle of phases and the moons revolution is due to Earth’s revolution
Video
Caused by the revolution of the moon
Occur when the Earth or moon block out the sun
Can only occur when the sun, Earth and moon are lined up perfectly
Solar eclipse happens during a new moon
Lunar eclipse happens during a full moon
Occurs when the moon moves directly between the sun and the Earth
It casts a shadow over part of the Earth Umbra-darkest part of the Moon’s shadow
Experience a total solar eclipse-can only see a pearly white glow around the edge
Penumbra-lighter shadow that surrounds the umbra◦Experience a partial solar eclipse
Never look directly at the Sun, it can cause permanent eye damage
•Earth’s shadow falls on the Moon•Begins when the moon moves into the Earth’s penumbra•Curved shadow from Earth forms on the Moon•Total lunar eclipse-Moon completely in Earth’s umbra•Partial lunar eclipse-portion of the Moon moves into Earth’s umbra•Sunlight bent through Earth’s atmosphere-eclipse moon is red
craters-caused by meteorites, asteroids and comets
Dark, flat regions are called maria◦Formed from lava◦Igneous rock is 3-4 billion years old
Moon must have once been geologically active as Earth is today
Use seismograph to study moonquakes
Has helped them draw models of moons interior
Figure 11 Pg 671
Apollo mission supported a new theory about Moon:◦The Moon formed billions of years ago when Earth collided with a Mars-sized object
◦A ring of gas and debris formed around earth
◦Particles joined together to form the moon
Studying the moon has helped scientists draw conclusions about:◦Earth’s shape◦Movement of Earth and Moon around the Sun
◦Presence of surfaced features on bodies other than Earth