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Transcript
Earth, Sun, and Moon Physical Properties of Earth Diameter (pole to pole) Diameter (equator) Circumference (poles) Circumference (equator) Mass Density Average distance to sun Period of Rotation Period of Revolution 12,714 km 12,756 km 40,008 km 40,075 km 5.98 x 1027 g 5.52 g/cm3 149,600,000 km 23 hr 56 min 365 days 6 hr 9 min Motions of the Earth 1) Rotation 1. 2) Revolution 1) 3) Turning or spinning on its axis Earth revolving around the sun in an elliptical orbit Precession 1) Slight movement over a period of 26,000 years of Earth’s axis Rotation 2 ways of measuring 1) Solar Day – time from one noon to the next 2) Sidereal Day- time it takes Earth to complete one full rotation (360 degrees) with respect to another star other than our sun Time required for a star to reappear at the identical position in the sky where it was observed the day before 23 hours 56 minutes Revolution Earth revolves around the sun in an elliptical orbit at an average speed of 107,000 kilometers/hour Average distance from the sun is 150 million kilometers Perihelion- Earth is closest to the sun 147 million kilometers away (January) Aphelion- Earth is farthest from the sun about 152 million kilometers away (July) Precession Earth wobbles on its 23.5o axis and North pole points to different stars in 26,000 year period Now points towards Polaris In 14,000 will point to Vega By 28,000 will point to Polaris again Has a slight affect on seasons Seasons The northern hemisphere experiences summer when Earth is farthest from the sun. It experiences winter when Earth is closest to the sun. The seasons are a result of the Earth’s tilt on its axis. Remember Earth’s axis is at a 23.5o tilt. Equinox Equinox is the time when the sun is directly on Earth’s equator. Number of daytime hours = Number of nighttime hours Northern and Southern Hemispheres are not tilted toward the sun. Spring Equinox – Around March 20, 21 Fall Equinox – September 22, 23 Solstice The point when the sun reaches its greatest distance north or south of the equator. Summer Solstice – June 21, 22 Long days, shorter nights Winter Solstice – December 21, 22 Short days, longer nights http://esminfo.prenhall.com/science/geoanimati ons/animations/01_EarthSun_E2.html Earth-Sun Motion Earth, Sun, and solar system speeds in the direction of the bright star Vega at 20 Kilometers per second Also- Sun revolves around the galaxy Galaxies themselves are also in motion We are approaching Andromeda Earth’s Moon (Luna) Earth’s only natural satellite (objects that are in Earth’s orbit) Density is 3.3X greater than mantle rocks of Earth Gravitational attraction is 1/6 of that on Earth- 150lb on Earth = 25 lb on the moon Earth’s Moon The moon rotates on its axis, and revolves around the earth. Moon’s rotations = 1 rotation every 27.3 days Moon’s revolution = 1 rev. every 27.3 days Because the revolution and rotation times are the same, we always see the same side of the moon. The moon shines because of light being reflected from the sun. Moon phases are the changing appearances of the moon as seen from Earth. Phases of the Moon New Moon – the lighted half of the moon is facing the sun and dark side faces the earth. Occurs when the moon is between Earth and the sun. Waxing – Shortly after the new moon, more and more of the moon’s lighted side becomes visible (about 24 hours after new moon) Waxing occurs until we see the full moon Waning Phases Happens after the full moon, when the moon’s lighted side becomes smaller. Waning gibbous occurs after the full moon. Then third quarter phase occurs Next comes waning crescent Finally the waning phase ends with a new moon. New Moon Waxing Crescent (Anything small than a quarter) First Quarter Waxing Gibbous (More than one-quarter is visible) Full Moon Names for the Full Moon January: Wolf or Hunger moon. During this month the wolves once roamed the countryside, thus suggesting the name wolf moon. In cold and temperate climates of the Northern Hemisphere, it was difficult to find food during January, thus the name hunger moon. February: Snow Moon. In certain parts of the world, snow is usually the deepest in this month, thus the name snow moon. March: Sap or Worm Moon. Because sap rises in March, this full moon is called the sap moon. The ground softens during this month, and worms begin to burrow out of the ground, thus the name worm moon. April: Pink Moon. Many flowers turn pink and bloom in April, thus the name pink moon. May: Flower Moon. Because many flowers bloom in May, after the April downpours, May's moon is called the flower moon. June: Strawberry or Rose Moon. Because strawberries bloom in June, this month's moon is the strawberry moon. Also, the French call this moon la lune rose, which translates into English as "the rose moon." Names for the Full Moon Continued July: Buck Moon. Male deer, or bucks, grow their first antlers during this month, thus the name buck moon. August: Sturgeon Moon. Because it is sturgeon season in certain parts of the world in August, its moon is called the sturgeon moon September: Harvest or Corn Moon. Native Americans began to harvest their crops during this month every year. (If this full moon occurs late in August it is called the harvest moon.). If the full moon occurs earlier in September, it is called the corn moon because the corn crop is ready for picking at that time. October: Hunter's Moon. The hunting season begins in October, thus the name hunter's moon. November: Beaver Moon. Beaver traps were once set in this month to catch enough beaver to make warm clothing for the upcoming winter. December: Cold Moon. The approach of cold weather in the Northern Hemisphere gives this month's full moon its name. Compton's Interactive Encyclopedia Waning Gibbous Third (Last) Quarter Waning Crescent New Moon (Cycle starts over again!!!) Eclipses Shadow effects When the moon moves in a line directly between Earth and the Sun it casts a shadow on Earth- Solar Eclipse When the moon moves within Earth’s shadowLunar Eclipse The revolution of the moon causes eclipses What does the moon revolve around? Solar Eclipses Umbra – Darkest portion of the moon’s shadow (Total Eclipse) Penumbra – Surrounds the umbra and is lighter shadow on Earth’s surface (Partial Eclipse) Caution: Regardless of where you are standing, never look directly at a solar eclipse. The light will permanently damage your eyes. Lunar Eclipse Happens when the shadow of Earth falls on the moon. Moon moves into Earth’s penumbra. Continues to move, enters the umbra, and you see a curved shadow on the moon’s surface. Partial Lunar Eclipse Only a portion of the moon moves into Earth’s umbra Total Lunar Eclipse (January 2000) Structure of the Moon Don’t believe everything you read. Discovery of life on the Moon was announced to the American public by the New York Sun in 1835. This fanciful illustration is supposed to have shown what astronomers were seeing with new and more powerful telescopes. Structures of the Moon Maria are dark-colored, relatively flat regions on the moon. Formed when ancient lava flows from the moon’s interior filled large basins on the moon’s surface. Some are 3 to 4 Billion years old and are the youngest rocks on the moon Highlands- densely pitted light-colored areas Regolith- soil-like layer composted of igneous rock, glass beads, and fine lunar dust Maria Maria Craters Most obvious features on the moon Depression formed by meteorites, asteroids, and comets, which struck the moon. Cracks have formed in the moon, during impacts Many more than Earth because the moon has no atmosphere to burn up debris and no destruction by tectonic forces South Pole of the Moon Surface seen by Apollo 11 on its decent to the moon Apollo 11 Moon Interior Core Mantle Crust Moon’s Interior Earthquakes allow scientists to map the moon’s interior. Seismographs were left by Apollo astronauts Crust: 60 km thick on the side facing Earth 150 km thick on the far side Mantle: solid mantle, maybe 1000 km thick Core: May be a solid iron-rich core False Color Mosaic Taken by Galileo in 1992 Red = Lunar Highland Blue & Orange = ancient lava flows Blue regions contain more titanium than orange Purple = regions that formed during large volcanic eruptions Moon dust under microscope Mostly titanium and iron oxides Origins of the Moon Three popular theories, prior to the Apollo missions: 1. 2. 3. Moon was captured by Earth’s gravity Moon condensed from loose material surrounding Earth during the formation of the solar system. Blob of molten material was ejected from Earth while Earth was still in its early stage. Impact Theory Impact Theory Moon formed around 4.6 billion years ago when a Mars-sized object collided with Earth Melted part of Earth’s Mantle and the impacting object. Material ejected into space Debris started orbiting the Earth, some debris fell back to Earth Material formed a ring of hot dust and gas around Earth In about 100 years, the particles in the ring joined together forming the moon Future Moon Missions Will there be future missions to the moon? Will there be colonies on the moon? How can we sustain life on the moon? Please take a few moments to think about these questions.