Presentation on theme: "Earth’s Moon. Moons Satellites are natural or artificial bodies that revolve around larger bodies such as planets. Moons are natural satellites. All the."— Presentation transcript:
Moons Satellites are natural or artificial bodies that revolve around larger bodies such as planets. Moons are natural satellites. All the planets in the solar system have them except Mercury and Venus. –Ours is named Luna, but we just call it the moon.
Composition/Age Is not made of the same material as Earth –It is less dense than earth is –It has a lower percentage of heavy elements –Rock composition is similar to Earth’s mantle Rocks brought back from Apollo missions are about 4.6 billion years old –This tells us the age of the solar system because they are unchanged
Revolution/Rotation The period of revolution around the Earth is 27 days, 8 hours The period of rotation on its axis is 27 days 8 hours This means the moon takes as long to rotate on its axis as it does to revolve around the earth!! –This has to do with Tidal Force (more later).
Lunar Origins The old theory was that –1) It was captured by Earth’s Gravity (too big) –2) It formed at the same time from the same materials as Earth (it isn’t) –3) New Earth spun a piece off and it became the moon (bad physics) The current theory is there was a planetary collision with a smaller planet that put some of Earth’s mantle into orbit. It formed into a moon.
Half an Hour After the Giant Impact, based on computer modeling by A. Cameron, W. Benz, J. Melosh, and others. Copyright William K. Hartmann Five Hours After Impact, based on computer modeling by A. Cameron, W. Benz, J. Melosh, and others. Copyright William K. Hartmann
The Moon passes through four major shapes during a cycle that repeats itself every 27.5 days. The phases always follow one another in the same order: New moon First quarter Full moon Third quarter
New Moon The lighted side of the Moon faces away from the Earth. This means that the Sun, Earth, and Moon are almost in a straight line, with the Moon in between the Sun and the Earth. The Moon that we see looks very dark
First Quarter Moon The right half of the Moon appears lighted and the left side of the Moon appears dark. During the time between the New Moon and the First Quarter Moon, the part of the Moon that appears lighted gets larger and larger every day, and will continue to grow until the Full Moon.
Full Moon The lighted side of the Moon faces the Earth. This means that the Earth, Sun, and Moon are nearly in a straight line, with the Earth in the middle. The Moon that we see is very bright from the sunlight reflecting off it.
Third (Last) Quarter Moon Sometimes called Third Quarter. The left half of the Moon appears lighted, and the right side of the Moon appears dark. During the time between the Full Moon and the Last Quarter Moon, the part of the Moon that appears lighted gets smaller and smaller every day. It will continue to shrink until the New Moon, when the cycle starts all over again.
Moon Movie The movie is an animated GIF created by Antonio Cidadao from a sequence of still images taken during March and April 1998. Copyright Antonio Cidadao.Antonio Cidadao http://aa.usno.navy.mil/faq/docs/mo on_phases.html
An eclipse occurs when one celestial body falls on another –A lunar eclipse happens when the Earth comes between the sun and the moon –A solar eclipse happens when the moon comes between the Earth and the sun The shadow of the moon falls on part of the Earth
Lunar Eclipse Earth is between the sun and moon Earth’s atmosphere acts like a lens and bends some of the sunlight into Earth’s shadow. This filters out blue light – causing the moon to illuminate red
Solar Eclipse The moon comes between the Earth and the sun The moon appears the same size as the sun in the sky –It almost covers the sun during a solar eclipse –Occasionally, the moon is further away from the Earth because its orbit is elliptical and there is a thin ring of sunlight around the moon. This is an annular eclipse.
The Moon & the Tides www.galaxypix.com/ar twork1/otherart
Tidal Forces Tides are daily movements of ocean water that change the level of the ocean’s surface –They are influenced by the sun and moon –Discovered 2000 years ago, but not explained until NEWTON – principle of gravitational pull –The gravity of the moon pulls on everything on Earth, but is more noticeable on liquids
High Tide The position of the moon determines how high the tide is and when it occurs The pull is strongest on the part of the Earth facing the moon If that part is ocean, then it bulges to the moon At the same time, the water on the other side of the Earth bulges due to the motion of the earth. This is high tide.
Low Tide While water is bulging out at high tide in two areas, water has to be drawn away from the other two areas on the globe. This causes a “flattening” in those areas – less water is there. The phenomenon of having less water during that time is called low tide.
As the Earth moves around the Sun, this axis stays always pointing in the same direction.
This means: during part of the year, the northern part of the Earth will lean more directly to the sun during other parts of the year the southern part of the Earth will.
The Earth during one full year as you would see it if you looked straight at it from the Sun.
The part of the Earth that is directly facing the sun changes with the time of the year.
The northern half faces the sun for a while, then moves south of the equator, only to move back to the north again.
When the northern hemisphere is leaning away from the sun, the rays coming from it hit this part of the Earth at a smaller angle than on other parts of the world.
This means that the same amount of light is distributed over a larger surface, and so these places receive less heat than the others.
The southern hemisphere is experiencing Summer, the northern hemisphere has Winter.
In half a year, the situation reverses, and it is now Winter in the southern hemisphere since that part of the earth is now leaning away from the sun.
The energy that hits the Earth by the Sun changes over of the year. The angle the Sun is above the horizon determines how much heat and light strike each square meter of ground. http://inkido.indiana.edu/a100/celestialsphere5.html
In the winter the Sun's energy is weakened because the Sun's ray strike the ground rather indirectly as compared to the summer months when the Sun's rays strike the ground more directly. http://inkido.indiana.edu/a100/celestialsphere5.html
This means: The ground receives more energy (more heat) per square meter in the summer than in the winter. More energy is received by the ground during the summer (high temperatures) and less energy during the winter (lower temperatures). http://inkido.indiana.edu/a100/celestialsphere5.html
So, seasons are caused by the tilt of the Earth’s axis
Remember: The seasons are the result of the tilt of the Earth's axis. If the tilt of the Earth's axis was 0° there would be no difference in how the rays from the sun hit its different regions, and there would be no seasons.
The Earth's seasons are not caused by the differences in the distance from the Sun throughout the year.
The seasons are the result of the tilt of the Earth's axis. I know this is a repeat, but it is important that you understand this idea. Many Americans, including Harvard graduates, do not know what causes seasons!
Review Look closely at where the Sun is hitting the Earth during each season: http://Search.Lycos.com/setup.asp?r=5&src=clear2&query=weather+savvy