NC Earth Science Essential Standards EEn. 1.1 Explain the Earth s role as a body in Space. EEn. 1.1.1 Explain the Earth s motion through space, including precession, nutation, the barycenter, and its path about the galaxy. EEn. 1.1.2 Explain how the Earth s rotation and revolution about the Sun affect its shape and is related to seasons and tides. EEn. 1.1.3 Explain how the sun produces energy, which is transferred to the Earth by radiation. EEn. 1.1.4 Explain how incoming solar energy makes life possible on Earth. [National Science Content Standards:] UCP.1, UPC.2, UPC.3, UPC.4, UCP.5; A.1, A.2; B.4; D.1, D.3; E.1, E.2; F.6; G.1, G.2, G.3
Reading Assignment: Read Chapter 28; pages 746-767 Objective: -Describe electromagnetic radiation; - Explain how telescopes work; -Describe space exploration; -Describe the development of exploration of the Moon; -Identify features on the Moon; -Explain the theories about how the Moon formed; -Identify the relative positons and motions of Earth, the Sun, and the Moon; -Describe the phases of the Moon; -Explain eclipses of the Sun and Moon. Vocabulary: electromagnetic spectrum wavelengths frequency speed of light refracting telescope interferometry highland mare impact crater ejecta rille regolith solstice equinox solar eclipse perigee Apogee lunar eclipse
Tools of Astronomy Radiation Telescopes Satellites, probes, and space-based astronomy The best tool astronomers use is the light that comes to Earth from distant objects.
Electromagnetic Spectrum Longest wavelength are to the right and the shortest wavelength are to the left. Electromagnetic radiation consists of electric and magnetic disturbances, traveling through space as waves. Includes: visible light, radio waves, microwaves, infrared, visible light, ultraviolet, X rays, and gamma rays. (All electromagnetic radiation travels at the speed of light, 300,000 km/s or 186,300 m/s)
Telescopes Since eye can only detect a small portion of electromagnetic spectrum, we use various types of telescopes. Benefits: 1. Able to observe all wavelengths. 2. Brings much more light into focus. 3. Permits use of specialized equipment (like photometers). 4. Can use cameras or other imaging devices.
Two different types of telescopes used to focus visible light. Refracting Telescope: Uses lens to bring visible light to a focus. Reflecting Telescope: Brings visible light into focus using mirrors. (Hans Lippershey of Holland Invented the spyglass in 1608; Galileo made one, used one, to view study the heavens, and improved it.) (Sir Isaac Newton, is credited for building the first reflecting telescope in 1668.)
Interferometry Process of linking separate telescopes together to act as one telescope; Detail in the images improves as the distance between the telescopes increases.
Satellites, Probes, and Space-based Astronomy Satellites and probes are sent into outer space due to Earth s atmosphere blocking infrared radiation, ultraviolet radiation, X rays, and gamma rays. Another reason: make close-up observations and possibly collect or obtain samples from nearby objects in space.
Hubble Space Telescope (HST) Best-known spaced based observatories is the Hubble Space Telescope (HST), which was launched in 1990, designed to obtain sharp visible-light images without atmospheric interference, and also to make observations in infrared and ultraviolet wavelengths. http://hubblesite.org/gallery/album/galaxy
Spacecraft Spacecraft Space based exploration is achieved by sending spacecraft directly to the bodies being observed. Probes are practical only for objects within our solar system. Twin robots, Spirit and Opportunity, conducted experiments on Mars in 2004.
Human Spaceflight Space shuttle allowed the study the effects of weightlessness on humans, plants, the growth of crystals, and other phenomena.
International Space Station (ISS) Multi-country * space station called the International Space Station (ISS) is the ideal environment to study the longterm effects of space. Areas of research include: growing cells in zero gravity and testing the effect of zero gravity on plants, animals. * Countries include: NASA, Russian Federal Space Agency, Japanese Aerospace Exploration Agency, Canadian Space Agency, the European Space Agency has the following 10 countries: Belgium, Denmark, France, Spain, Italy, Germany, the Netherlands, Norway, Switzerland, and Sweden, and Brazil contributed to the construction of the ISS.
Space-exploration Spinoffs Include: Artificial hearts, Automotive insulation, Balance evaluation system Bioreactor, Diagnostic instrument, Gas detector, Infrared camera, Land mine removal device, Lifesaving light, Prosthesis material, Vehicle tracking sys, Rescue tool, Video stabilization software, and About 1400 different items
The Moon Only within the past 100 years, had we begun to understand the moon. We learned much about the moon through telescopes and observations, however, most of our knowledge came from the space probes such as Lunar Prospector and Clementine, and astronauts. Space race began in 1957, when the Soviet Union launched the first satellite into space called Sputnik I, which was not much bigger than a beach ball.
Yuri A. Gagarin First human in space (Soviet Union), April 12, 1961, flight lasted 108 minutes aboard the Vostik I. Alan B. Shepard Second human (first American) in space, May 5, 1961, flight lasted 15 minutes and 28 seconds aboard the Freedom 7.
Lunar Properties Earth s moon is unique among all the moons Moon s orbit is relatively farther from Earth than most moons are from their planets. Solid, rocky body, in contrast to icy composition of outer planet moons of Jupiter, Saturn, Uranus, Neptune, and Pluto (dwarf) Only large moon among the inner planets (Mercury and Venus have no moons and at all and the moons of Mars has two tiny chunks of rock orbiting it.) Minerals similar to Earth; mostly silicates (oxygen and silicon); also contains high quantities of calcium and aluminum, and low quantities of iron
The Lunar Surface Although the moon is the brightest object in the nighttime sky, the lunar surface is actually quite dark. The Albedo of the moon is the amount of sunlight that its surface reflects, only about 7 percent.
Physical features of the Moon Highlands Regions that are light in color, mountainous, and heavily covered with craters. Maria Dark, smooth plains which are about 3 km lower in elevation than the highlands. No erosion, no atmosphere, no flowing water, no surface creep, but a lot of wear caused by impacts. With no atmosphere, the sun heats the surface to as high as 400 K (127 C) and at night cools to 100 K (-173 C).
Physical Features Continued Impact Craters All of the craters on the moon are called impact craters. These are formed when objects from space crashed into the lunar surface. Ejecta The material blasted out during these impacts fell back to the surface as ejecta.
Physical Features Continued Rays Long trails of ejecta that radiate outward. Visible on the moon as light colored streaks. Rilles within Maria Meandering, valleylike structures.
History of the Moon Radiometric dating of lunar rocks, predict the moon to be 3.8 to 4.6 billion years old. Scientist theorize the moon was heavily bombarded which resulted in breaking and heating of rocks on the surface of the moon, This formed a layer of loose, ground-up rock called regolith, on its surface.
Physical Features Continued Photo of the far side of the moon shows the heavily cratered surface of the highlands. Crust varies in thickness, and is thickest on the far side.
Tectonics on the Moon? Moon, like Earth, has a layered structure, which consists of the crust, the upper mantle, the lower mantle, and the core. Moon experiences moderate moonquakes (one per year) Scientists theorize that the Moon is not tectonically active. Moon has no active volcanoes and no significant magnetic field.
Formation Theories Capture theory, Simultaneous Formation theory, and the Impact Theory (which is most accepted). Moon formed as the result of a gigantic collision between Earth and a Mars-sized object about 4.5 billion years ago, when the solar system was forming. Result of the collision, materials from incoming body and from Earth s outer layers were ejected into space, where they then merged together to form the Moon.
The Sun-Earth-Moon System
The Sun and Moon Sun- Provides light and warmth and is the main source of energy that fuels our society. Moon- Raises tides in our oceans and illuminates our sky with its monthly cycle of phases. Every society from ancient times to the present has based its calendar and its timekeeping system on the motions of the Sun and Moon.
Earth s Rotation.. The sun, moon, planets, and stars rise in the east and set in the west. The sun, moon, planets, and stars do not orbit around Earth everyday. It only appears that way because we observe the sky from a planet that rotates once every day or 15 per hour.
How do we know the Earth is rotating? There are two relatively simple ways to demonstrate that Earth is rotating. With a Foucault pendulum pegs are often placed on the floor in a circle so that as the Earth turns, the pendulum eventually knocks over each of the pegs, showing from our view point that the pendulum gradually shifts its orientation reflecting the Earth s rotation. Foucault (fü- kó) pendulum, has a long wire, a heavy weight, and will swing in a constant direction,
How else do we know the Earth is rotating? The other method to demonstrate the Earth s rotation is the fact that flowing air and water on Earth are diverted from a north-south direction to an east-west direction as a result of the Earth s rotation. This diversion of direction is called the Coriolis effect. The Coriolis Effect: Deflects moving particles such as air to the right above the equator and to the left below the equator; Caused by Earth s rotation and combines with the heat imbalance found on Earth to create: trade winds, polar easterlies, and prevailing westerlies.
Annual Motions The annual changes in length of days and temperature are the result of Earth s orbital motion about the Sun. The ecliptic is the plane in which Earth orbits about the Sun.
Annual Motions The Effects of Earth s Tilt Earth s axis is tilted relative to the ecliptic at approximately 23.5 (range: 22.5º to 24.5º). As Earth orbits the Sun, the orientation of Earth s axis remains fixed in space, pointing to the North Star. During summer, in the northern hemisphere the Earth is tilted toward the Sun, while during winter, the Earth is tipped away from the Sun. As a result of the tilt of Earth s axis and Earth s motion around the Sun, the Sun is at a higher altitude in the sky during summer than during the winter.
Annual Motions The Effects of Earth s Tilt Altitude is measured in degrees from the observer s horizon to the object. There are 90 degrees from the horizon to the point directly overhead, called the zenith of the observer.
Annual Motions Solstices As Earth moves from position 1, through position 2, to position 3, the altitude of the Sun decreases in the northern hemisphere. Once Earth is at position 3, the Sun s altitude starts to increase as Earth moves through position 4 and back to position 1. Summer Spring Winter Fall
Annual Motions Solstices The summer solstice occurs around June 21 each year when the Sun is directly overhead at the Tropic of Cancer, which is at 23.5 N. The summer solstice corresponds to the Sun s maximum altitude in the sky in the northern hemisphere.
Annual Motions Solstices The winter solstice occurs around December 21 each year when the Sun is directly overhead at the Tropic of Capricorn which is at 23.5 S. The winter solstice corresponds to the Sun s lowest altitude in the sky in the northern hemisphere.
Annual Motions Equinoxes When the Sun is directly overhead at the equator, both hemispheres receive equal amounts of sunlight. Autumnal equinox occurs around September 21, halfway between the summer and the winter solstices when the Sun is directly over the equator.
Annual Motions Equinoxes Vernal equinox occurs around March 21, halfway between the winter and the summer solstices when the Sun is directly over the equator. For an observer at the Tropic of Cancer or Tropic of Capricorn, the Sun is 23.5 from the point directly overhead during the equinoxes.
Annual Motions Equinoxes For a person standing at the x at 23.5º N, the Sun would appear in these positions on the winter solstice, the vernal equinox, and the summer solstice. On the autumnal equinox, the Sun would be at the same altitude as on the vernal equinox.
Earth s Axis Precessional movement of the Earth: the Earth rotates (white arrows) once a day about its axis of rotation (red line), this axis itself rotates slowly (white circle), completing a rotation in approximately 26,000 years. Rotation (green), precession (blue) and nutation in axial tilt (red) of a planet. A vertical line (grey) is drawn perpendicular to the plane of each planet's orbit.
Earth s Axis Currently the axis points toward the North Star, Polaris, but will tilt toward another star, Vega, we predict in the year 14,000 Currently in the Northern Hemisphere, summer occurs when Earth is furthest from the Sun; and winter occurs when Earth is closest to the Sun When we change axis, summer will occur when Earth is closest to the sun and winter will occur when Earth is furthest from the Sun in the Northern Hemisphere.
Eccentricity Earth s orbit appears to change between elliptical and circular orbits over the course of a 100,000 year cycle With an elliptical orbit, as the Earth passes closer to the Sun, the temperatures become warmer than normal When the orbit is circular, as the Earth is further from the Sun, the temperatures dip below average
Why do we have moon phases? The movement of the moon around earth and our changing viewpoint on Earth relative to the Sun. The moon does not emit visible light. We see the Moon s reflection of Sun s light.
Lunar Phases Sequential changes in the appearance of the Moon are called lunar phases. Closest point in the moon s elliptical orbit is called perigee and the farthest point is called apogee.
Lunar Phases As the Moon moves along in its orbit, the amount of reflected sunlight that we can see increases. The increasing in the portion of the sunlit side of the Moon we see is called waxing. (phases move in counter clockwise direction, beginning with new moon)
Lunar Phases Once a full moon is reached, the portion of the sunlit side that we see begins to decrease as the Moon moves back towards the newmoon phase The decrease in the sunlit side is called waning The phases continue in the reverse order of the waxing phases.
Synchronous Rotation Scientists theorize, that Earth s gravity slowed the Moon s original spin until the Moon reached a synchronous rotation, the state at which its orbital and rotational periods are equal. This results are the same side of the Moon always faces the Earth, this means we see the same side of the Moon at night, during the Lunar Phases. Ex. New moon to new moon Length of lunar month: 29.5 days Moon s orbit around Earth: 27.3 days
Eclipses Continued Solar Occurs when the Moon passes directly between the Sun and Earth and blocks our view of the Sun. Lunar Occurs when the Moon passes through Earth s shadow.
During Eclipses a solar eclipse Continued people within the umbra witness a total eclipse; those within the penumbra shadow, witness a partial eclipse. (note: umbra shadow no wider than 270 km). Reasons we do not see a solar eclipse every month, due to a 5 tilt in the Moon s orbit, the plane of the Earth, Moon, and Sun are not always in proper alignment, and the Moon s distance from the Earth increases or decreases due to the Moon s elliptical orbit.
During Eclipses a lunar eclipse the Continued moon passes through the Earth s shadow. This can only happen during a Full Moon. A total lunar eclipse occurs when the entire Moon is within the Earth s umbra, and lasts for about two hours. The Moon will be faintly visible, and because sunlight that has passed near Earth has been refracted by Earth s atmosphere, the Moon will have a reddish color. Like solar eclipses, lunar eclipses do not occur every full moon, because the Moon in its orbit usually passes above or below the Sun as seen from Earth. Solar and lunar eclipses occur in almost equal in numbers, with slightly more lunar eclipses. Maximum number of combined eclipses occurring in a year was seven, in 1982.
Questions?
Describe the Moon s affect on Earth s tides? The Moon s gravity pulls on Earth and creates a bulge in ocean water on both the near and far sides of Earth Along with Earth s rotation also causes the formation of tides.
One of the Moon s effects on Earth is the formation of tides. The Moon s gravity pulls on Earth along an imaginary line connecting Earth and the Moon, and this creates bulges of ocean water on both the near and far sides of Earth. Earth s rotation also contributes to tides. The ocean level rises and falls every 12 hours. Tides Moon creates stronger tides on the ocean versus that of the Sun because it is closer to the Earth. 2 Types of tides
Spring Tides occurs when the Sun, the Moon and Earth are aligned. the tides are higher than normal Full or New Moon Especially high when the Moon is nearest the Earth and Earth is nearest the Sun
Neap Tides occurs when the Sun, the Moon, and Earth form a right angle. the tides are lower than normal 1 st and 3 rd Quarter Spring and Neap tides alternate every two weeks.
Why is the Earth largest around the equator? Equatorial bulge- due to centrifugal force from the rotation of the Earth. When the model is not in motion the tension of the elastic band keeps it in a circular shape. Equator diameter is 42 km longer than the polar diameter. Spinning the ring-shaped band makes it bulge out.
As the moon orbits Earth perigee it passes apogee it appears to go through phases lunar eclipse it may cause solar eclipse new moon waxing such as full moon waning which involve the shadows called umbra penumbra
The sun Is composed of several layers including core radiative zone convention zone photosphere corona in which there is nuclear fusion