Chapter 1-3 Astronomy PDF

Chapter 1 Introduction to Astronomy Chapter Objectives: 1. Explain the immense definition of astronomy 2. Understand the historical perspective of astronomy 3. Appraise the role of astronomy in everyday life 4. Anticipate the role of astronomical instruments for s...

Chapter 1 Introduction to Astronomy Chapter Objectives: 1. Explain the immense definition of astronomy 2. Understand the historical perspective of astronomy 3. Appraise the role of astronomy in everyday life 4. Anticipate the role of astronomical instruments for speed observation and research Introduction Most of the youngsters are captivated with the sky. Even the early people who lived before us had always been sky watchers. Astronomy is one of the most fascinating sciences. The journey of astronomy is to learn more about what is out there even beyond the solar systems. Astronomy tells us how the universe works with its numerous stars, planets, and galaxies. The stars and the sky itself have aided humanity in many ways; they guided the navigation system of ancient people, farmers were guided in identifying seasons, fisherman were guided in determining good fishing schedules and many others. Historical Perspective  Astronomical timeline can be dated back to 3000 BC when the Sumerians record the brightest stars and form the first zodiac of constellations.  From about 2550-2490 BC, the pyramids of Giza in Egypt are built, perhaps to reflect the positions or the stars.  In 2296 BC the first recorded observation of a comet made by Chinese astronomers. The Chinese also recorded a solar eclipse on 2137 BC.  In 2000 BC, lunar and solar calendars are developed In Egypt and Mesopotamia, and Babylonians use base-60 counting sexagesimal system which is still in use for counting time and angles. Also in that same year, Stonehenge in England was constructed to mark the solstice.  The oldest European star chart "Trundholm Chariot of the sun” created in Denmark about 1600-1400 BC.  In 1450 BC, Sundials are used in ancient Egypt and introduce the 365-day year. Solar eclipse recorded by Babylonians.  Thales of Miletus uses observational data to predict a solar eclipse and that Great philosopher Anaximander proposes the Earth is a cylinder floating in space in 580 BC.  In 440 BC, Leucippus suggests that the universe is made of indivisible atoms which is also the same time that Eudoxus describes the celestial sphere.  In 350 BC, Plato and Aristotle put Earth at the center of the universe, and Aristotle suggests that Earth and other heavenly bodies are round.  In 270 BC, Aristarchus opposes Plato's geocentric model, and proposes a heliocentric theory with the Sun at the center of the solar system, but his view was largely dismissed.  By 194 BC, Eratosthenes calculates the size of the Earth using the angle of the Sun. One of the early astronomic instruments was invented in 150 BC when Hipparchus invents astrolabe.  By 120 BC, Hipparchus divides the night sky into longitude and latitude; he also shows that Earth wobbles on its axis as it rotates, known as precession.  The Antikythera mechanism, a mechanical gear predicting the motion of heavenly bodies is built in 65 BC.  Julius Cezar reforms the Roman calendar, creating the "Julian Calendar” upon which the modern one is based in 46 BC.  Al-Biruni calculates the circumference of Earth using measurements taken from a mountain top in lndia in 990.  In 1054, Chinese astronomers see the supernova that creates Crab nebula.  In 1543, Copernicus publishes details of his heliocentric universe where Earth and the planets orbit the sun.  In 1570s Tycho Brahe makes the most detailed survey of the night's sky to date.  The Georgian calendar, named for the Pope Gregory XIII, is introduced to correct the drift of the Julian calendar in 1582.  By 1600, William Gilbert reveals that Earth has its own magnetic field.  In 1608, Hans Lippershey invents the optical telescope using glass lenses.  In 1609, Kepler's laws of planetary motion shows that orbiting bodies move in ellipses do not circle.  Galileo publishes his observations of the Sun, Moon and planets in "the starry messenger in 1610.  Jeremiah Horrocks observes the transit of Venus having predicted its occurrence using Kepler's law in 1639.  By the year 1655, Christian Huygens suggests that the strange shape of Saturn is due to rings around the planet.  In 1668, Isaac Newton presents his designs of the reflecting telescope to the royal society of London.  In 1675, the royal observatory isfounded at Greenwich near London, becoming the position of the prime meridian from which the world's time is measured.  In 1676, Ole Romer measures speed of light using observations of Jupiter's moons.  Isaac Newton presents his universal law of gravitation in 1687.  By the year 1705, Edmund Halley calculates orbital period of the comet that now takes his name, which arrives as he predicts.  In 1739, the French Geodesic Mission carries out measurements in Ecuador and Lapland to measure the shape of the Earth; it finds that the planet is flatter at the poles.  In 1750, Nicolas de Lacaille makes a detailed survey of the sky of the southern hemisphere.  In 1757, the sextant is invented as the latest navigational tool for calculating latitude.  In 1773, John Harrison's Chronometers are accepted as the best way to calculate longitude.  In 1779, Comte de Buffon times how long it takes for a ball or iron to cool and extrapolates the result to arrive a figure for the edge of the Earth 75,000 years.  In 1781, William Herschel finds a sixth planet which is eventually named Uranus.  Charles Messier completes his catalog of astronomical objects that do not appear to be stars in 1784. In that same year, John Goodricke defines the term Cepheid variable, a star that can be used to calculate interstellar distances.  In the dawn of the 19th Century, Giuseppe Piazzi finds Ceres, the first object in the asteroid belt.  In 1814, Joseph von Fraunhofer notices dark lines in the spectra coming from stars, founding the science of spectroscopy.  In 1835, Gaspard-Gustave Coriolis describes the apparent force behind the Coriolis Effect, in which the rotation of Earth causes wind and ocean currents to appear to be deflected.  In 1838, Friedrich Bessel uses the phenomenon of parallax to measure the distance of the stars and introduces the light-year as a unit of distance.  In 1835, William Parsons builds the leviathan, the largest telescope of the 19th century; it is used to observe the first spiral galaxy.  In 1846, Neptune is discovered following predictions of its orbit made by mathematician Urbain Le Verrier.  In 1851, Foucault's pendulum provides proof that Earth is rotating. Heinrich Schwabe suggests that sunspots appear according to an 11-year cycle.  In 1868, Helium is discovered in the atmosphere of the Sun by spectroscopic analysis of sunlight.  In 1877, Giovanni Schiaparelli draws a map on canal on Mars, fueling debate about alien life.  Sandford Fleming calls a conference in Washington, DC. O Standardize global time zones to 1884.  Konstantin Tsiolkovsky suggests ways to reach space in 1885.  In the 20th Century, Simon Newcomb measuresthe angle of Earth axisto the planes of the ecliptic (or orbit).  ln 1905, Albert Einstein's theory of special relativity makes Iight speed the speed limit of the Universe.  In 1912, Victor Hess detects exotic charged particles in the atmosphere, the first evidence of cosmic rays.  In 1913, the Hertzsprung-Russell diagram is used to group stars according to their size, temperature, and brightness.  In 1915, Einstein's theory of general relativity explains how space and time can be warped. Also in that same year, Karl Schwarzschild uses it to predict the existence of black holes.  In 1925, Edwin Hubble finds objectsfar beyond the limit of our galaxy, discovering that it isjust one of many other galaxiesin the Universe. The following year, Robert Goddard launches the first liquid-fueled rocket, making the prospect of space travel more likely.  In 1929, Edwin Hubble discovers that galaxies are more moving away from one another and the whole Universe is getting bigger. The next year, Clyde Tombaugh discovers Pluto, which is designated as the ninth planet.  In 1933, Subrahmanyan chandrasex calculates the size of a star needed to produce a supernova; Walter baade and Pritz Zwicky propose the existence of neutron stars. Jan Oort’s measurement of solar motion suggests that much of the mass of the universe is invincible, a concept that becomes known as dark matter.  In 1939, Hans Bethe explains how stars release energy through fusion.  In 1942, Werner von Braun V2 rocket bombs which make the first suborbital space flights.  In 1946, Fred Hoyle and others describe stellar nucleosynthesis, in which all elements heavier than Helium inside the stars.  In 1947, Chuck Yeager breaks the sound barrier with the Bell X-1 rocket plane.  Sputnik 1 becomesthe first artificial satellite in 1957 by year 196 two Russian dogs, Belka and Strelka, become the first to orbit Earth and return alive to the surface. lt is also the animal’s surface. It is also the time to Joe Kittinger parachutes from a balloon 31 km above the surface in conditions close to outer space.  In 1961, Yuri Gagarin becomes the first man in space.  ln 1962, NASA's Mariner 2 probe, exploring Venus is the first visitor to another planet.  In 1965, the cosmic microwave background, a radiation echo of the Big Bang, is detected coming from the whole sky.  In 1967, the first pulsars, which are neutron stars spinning at a huge speed and emitting beams of radiation, are discovered using a radio telescope. The first gamma ray burst is observed; these are the brightest events in the Universe.  In 1969, Apollo I mission: Neil Armstrong becomes the first person to walk on the Moon.  In 1971, Salyut 1 is the first space station in orbit around Earth.  In 1974, Sagittarius A, a giant black hole, is found at the center of the Milky Way galaxy.  In 1975, Venera 9 is the first craft to land on another planet, sending back the first pictures from the surface of Venus.  In 1976, Viking 1 is the first probe to land on Mars. In 1977, Voyagers 1 and 2 are launched to fly by the outer planets.  In 1979, the hirst magnetar, a magnetic neutron star, is discovered.  In 1981, NASA's Columbia shuttle makes its maiden flight into space, becoming the first reusable spacecraft.  In 1989, The Great Attractor, a massive and mysterious object thousands of times heavier than the entire Milky Way, is discovered at the heart of the Centaurus Supercluster Giotto and other probesfly past Halley's Comet on its most recent visit to Earth in 1987, SN 1987A becomes the first supernova witnessed by modern astronomers.  The Magellan orbiter makes a detailed map of the surface of Venus, normally hidden from view in 1990. Also, in that same year Hubble Space Telescope is launched.  In 1992, the Cosmic Background Explorer finds anomalies in the temperature of the Universe. In 1994, the Galileo probe en route to Jupiter takes pictures of Comet Shoemaker Levy 9 colliding with the giant planet.  In 1995, SOHO, the Solar and Heliospherie Observatory, is launched into a halo shaped orbit near to the Moon, where it images the Sun and searches for comets.  In 1996, NASA Scientist’s Suggest that a meteorite found in Antarctica and originally from Mars may contain evidence of primitive bacteria Iike forms.  In 1998, the expansion of the Universe is found to be speeding up, indicating a new and yet incomprehensible force called dark energy. The first module of the International Space Station is launched, currently the largest spacecraft in history.  Life scientists Peter Ward and Donald Brownlee propose the Rare Earth Hypothesis, arguing that Earth’s complex forms are the product of several factors that would be highly unlikely to be repeated elsewhere in the Universe in 2000.  Near Earth Asterojd Rendezvous (NEAR) Shoemaker lands on Eros, the first touchdown on an asteroid in 2001.  China is the third country in the world to send an astronaut into space in 2003.  By the year 2004, the Huygens lander finds lakes of gasoline on Titan, the largest moon of Saturn.  In 2006, PIuto and Ceres are reclassified as dwarf planets along with several large bodies found in the Kuiper belt with Pluto and Oort clouds.  New Horizons is launched with a rendezvous in 2015.  In 2011, the MESSENGER probe becomes the first to go into the orbit around Mercury. The Kepler Space Telescope finds several new including Kepler 22b, the most Earth-like planets. The Nature of Planetary Orbits A few years before Tycho Brahe died he hired a young assistant named Johannes Kepler. Kepler was a clever and hardworking man with geometrical background with plenty of unusual ideas. His knowledge of geometry with his stunning ideas, led him to visualize the geometric figures between the planets. When Brahe died, his observational data were passed on to Kepler. With this, Kepler was able to prove that Mars did not movealong a circular path but rather along an ellipse. Ellipse can be best described by its long and short dimensions called major axis and minor axis. For calculation purposes, the mostimportant value is the half the major axis length, or the semimajor axis. Furthermore, Kepler's measurements of Mar's orbit revealed that the sun is located not at the center of the ellipse but off-center, at one focus of the ellipse which is called eccentricity. Mathematically, eccentricity indicates how far the Sun is from the center of the ellipse as a fraction of the semimajor axis. Moreover, Kepler found out that Mars moves faster in its orbit when it is closer to the Sun. With this, he further described that with this geometrical illustration, the planet's speed varies with its distance from the Sun. Kepler's Law of Planetary Motion After years of studying observations of celestial objects, Kepler made three important discoveries about planetary motion as they revolve around the Sun. 1. Each planet revolves around the Sun in an elliptical orbit with the Sun at one focus. This law was proven right proved when he showed that Mars followed an elliptically shaped orbit. 2. The planets do not move at a constant velocity. This expresses that the planet is moving fastest when it is closest to the Sun and slowest when it is farthest from the sun. 3. A planet’s orbital period is proportional to the size of its orbit (its semi-major axis). Kepler's Third Law implies that the period for a planet to orbit the Sun increases rapidly with the radius of its orbit. There is a mathematical relationship between the two to complete one revolution around the sun and its average takes from the sun. The time required for planet make one called period of revolution. A planet’s period of revolution squared around is proportional to its distance from the sun cubed. The square period of a planet's orbit is proportional to the cube of the semimajor axis of that orbit. This also provides that the average distance major to the Sun is equal to 1 unit of distance which is called astronomical Unit. that light travels over one year, which translates into 5,865,696,000.00 miles or 9,460, 250,000,000 kilometers. So, if a galaxy is about 30 million lightyears away, you would multiply 30 million by the distance of a light year in Kilometers to get its exact distance from the Earth. Moreover, a light-year does not only show distance; it also reflects age as the distance. It also shows how it looked before. For example, if the Sun is 8.3 light minutes away from the Earth, this means that what we see is the light that got away from the Sun 8.3 minutes ago. The light from the next closest star is Proxima Centauri is about 4 light-years away from Earth, which means that the light we see from it left Proxima Centauri 4 years ago. So, if a certain galaxy is 65 million light years away, this also means that the light we see now on that galaxy left that galaxy 65 million years ago. Astronomical Unit Astronomers also use the term astronomical unit (AU) to define distance between the earth and the sun. It is equivalent to 149 million kilometers or 93 million miles. This unit 15 given to the distances between objects in the solar system, the distances are always given from the sun, the center of the solar system. The distance between the Earth and thesun is 1 AU, and the distance between Jupiter and the Sun is about 5.2 AU (depending onwhere it is in its orbit). Parsec If the distance is bigger, and if it seems that the unit light year will also run out to define the distance of a certain astronomical object astronomers also use the term parsec (pc). One parsec is 3.26 light years The Pleiades star cluster is around 150 pc (about 460 Iight years) away. The Coordinate System Cartesian Coordinates or Cartesian plane is a straight line that specifies each pointing a plane, by a pair of numerical coordinates which are the signed distances a point from two perpendicular lines. The Cartesian coordinates have X and Y axis X axis as the horizontal line; the left part is in negative, while the right part is in positive. The Y axis is the vertical line; the upper part of the axis is positive while the bottom part is in negative. coordinates have an origin also known as the (0, 0), the origin is where the line meets or it is the main point of all numerical coordinates or the pair of integers-2 1012 The Cartesian plane corresponds to an ordered pair such as (6, 3) first number plane corresponds to an ordered path the parenthesis is called the x coordinate, while the second number is the y- coordinate. Latitude and Longitude is an imaginary line on the globe. Latitude (Horizontal Line or Parallel line) is an angular distance; it is represented in degrees, minutes, and seconds, from the north or south of the equator. Longitude (Vertical Line); like that the latitude, is also an angular distance that is represented in degrees, minutes, and seconds. They point from east or west of the prime (Greenwich) meridian. Longitude is also called the meridian. Celestial Sphere is an imaginary sphere in the sky, showing the rising and setting points of celestial bodies (sun, moon, planets, and stars). It determines their positions in the sky. The celestial sphere is like a dome or where you only see the half of the sky. If you look at the sky, above your head, that's what you call the zenith, and if you look at eye level, that is called the horizon. The cardinals are north, east, south, and west. As the celestial sphere is a meridian, the imaginary circle passing from north and south points at the horizon and into the zenith is called celestial meridian. There is another coordinate system in celestial sphere, which is altitude-azimuth system. The altitude (vertical) of a staris the number of degrees above your horizon to the star. The azimuth (horizontal) is measured eastward along with the horizon from the north intersection of the horizon line from the zenith through the star the horizon. Always take note that the Earth isturning, and the coordinates constantly change, but the coordinates of celestial object that you measure will not be the same as those measured in different location.  Chapter 2 Astronomy in the Philippines Chapter Objectives: 1. Appraise the different branches of astronomy 2. Discuss the development of astronomy in the Philippines 3. Familiarize agencies that serves astronomy Introduction We define astronomy as the branch of physical science that covers the study of all extraterrestrial objects and phenomena. It is the scientific study of all objects beyond our world. Furthermore, it is a multidisciplinary science as it entangled with the study of physics, chemistry, mathematics, geology and biology. With the distinction, astronomy has the following branches: 1. Observational astronomy is the branch of astronomy that deals with data collection with the use of astronomical instruments. 2. Astrophysics is the study of physics of the universe. It deals with the physical nature of celestial bodies and analyzes the properties and interactions of cosmological objects. 3. Cosmology is the study of the origin, evolution, and the universal providence. 4. Astrobiology is the scientific study of the origin, evolution, distribution and possible existence of life in the universe. 5. Positional astronomy is the study of mathematical positioning of Celestial bodies. 6. Celestial mechanics is the study of the motion of the Celestial objects. 7. Astronomical philosophy is the study of the history and philosophical view of the concepts and Principles of astronomy by scientist, physicist, and astronomers. 8. Astronomy education is the branch of astronomy that deals with the transmission of astronomical learning, concepts and knowledge for formal education or community outreach. 9. Astronomy instrumentation is the study of the application of instruments and technologies towards astronomy. 10. Planetology is the study of comparative analysis of the chemical, physical, environmental, astrophysical, biological, and atmospheric inquiry of different planets in the solar system and beyond our solar system, exoplanets. Astronomy in the Philippines The following is an abstract from the research conducted by Dr. Cynthia Celebre of PAGASA. The development of astronomy in the Philippines each of the best presented in its form: Abstract The history of astronomy in the Philippines since it started in 1897 will be described. The development of astronomical resources, activities and education after its hundred years of existence will be emphasized. Historical Background Work in the astronomy in the Philippines started in 1897. It was one of the functions of the "Observatorio de Meteorologico de Manila" (OMM), which performed not only meteorological and astronomical services but also seismological and terrestrial magnetism services. Its astronomical activities were mostly limited to time keeping and observation of solar and stellar phenomena. The OMM began as a private institution 1865 and became it government agency that's the Weather Bureau in 1901 with its observatory in Manila as its central office. During the Second World War, the astronomical observatory was destroyed and a new observatory was constructed within the campus of the University of the Philippines in Quezon City in 1954. It remained there up to the present time, now under the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA), as the only government observatory. From 1954, the observatory has not seen any major change until 1998. The construction of a planetarium in the PAGASA Science Garden in Quezon City in September 1977 is the only addition to the facilities of the agency.  Likewise, its activities are practically the same, except for the publication of astronomical data and the conduct of occasional telescope and stargazing sessions up to 1993. Development of Astronomy At present, there are only two institutions in the country that perform astronomical functions. These include the PAGASA and the National Museum(NM) Planetarium, a government institution, which is under auspices of the Department of Education (DepEd). The succeeding paragraphs describe the development of astronomical resources and activities in PAGASA and education in the Philippines. PAGASA is presently under the supervision of the Department of Science and Technology (DOST) and is compose of nine branches or divisions, which in turn is composed of sections. The sections in astronomy is under the Atmospheric, Geophysical and Space Sciences Branch (AGSSB), which is basically the research and training arm of PAGASA. The Astronomy Research and Development Section (AsRDS) is staffed by 19 professional-level employees who hold college degrees and graduate studies and by 16 sub-professional-level employees. As earlier mentioned, PAGASA has an astronomical observatory and planetarium, which are both managed by AsRDS, AGSSB. In addition to its seven (7) small telescopes of various sizes, the largest of which is the 30-cm, the observatory acquired five (5) 25-cm and an 18-cm MEADE telescopes in 1998. Four (4) of the above-mentioned 25-cm telescopes where distributed to Legazpi, Cebu, Davao and Cagayan De Oro, the four regional field stations of PAGASA that are located at various parts of the country. The telescopes learn being utilized to promote astronomy in the countryside.  The greatest addition to the observatory is the 45-cm telescope that was donated by The Japanese government through its Cultural Grant-aid Program. To be able to accommodate the donated telescope and its accessories, the observatory was renovated in 1999. It was installed in 2000 and was inaugurated in 2001, replacing the 30-cm reflector type telescope that was formerly installed thereat. The donated telescope has a photometer and a spectrograph and its accessories. Unfortunately, in 2003, the photometer was stolen at the observatory. In 2001, Gunma Astronomical Observatory (GAO) of Japan donated an ST8 CCD. The spectrograph was also repaired of course that so that the donated CCD could be attached to it, Instead of a photographic camera. In addition to telescopes, the observatory is also equipped with aRb/GPS Timing System that replaced the old quartz clock on 20 February 2004. The timing system is being utilized for determining the Philippine Standard Time (PST) up to the nearest tenth of a second. The atomic clock is also equipped with a Network Time Protocol (NTP) system that allows the general public to check their time pieces through the Internet. The PAGASA Planetarium at the Science Garden but seat 100 people. The AsRDS personnel give astronomical lecturers to visitors, who are mostly students and teachers in elementary and high schools. Minor repairs were done inside the dome of the Planetarium in 2005 including the replacement of its worn-out chairs. Such renovation enabled the agency to increase the entrance fee being charged from 0.10 to 0.50 cents that is being used to help defray part of the maintenance expenses. In as much as most of the astronomical facilities or the country are located in Luzon, particularly is Metro Manila, that children and other astronomy enthusiasts who live for from these places are being deprived of making use of the said facilities. With the objective of reaching more people in the countryside thereby promoting astronomy to a greater number of people at a lesser cost, a mobile planetarium was acquired by the AsRDS in 1999. The said Planetarium has been traveling to various places upon request of interested parties on a first-come, first-served basis. Requesting parties in return shoulder all the expenses pertaining to the activity. Astronomy is taught as a part of the general science subject in elementary schools where it is normally given a three-hour per week period in Grades V and VI classes in the Philippines. It is an elective subject, which is taken in one semester (four months) in the first year high school level. Before 2002, there is no single University in the country that offers and astronomy course. In School Year (SY) 2002-2003, the University of the Philippines through its National Institute of Physics offered an astronomy subject entitled "Physics and Astronomy for Pedestrians". SY 2005-2006 marked a great change in history of Philippine Education in the field of astronomy. For the first time, the Rizal Technological University (RTU) offered a graduate program leading to a degree of Master of Science in Astronomy. This course, which is descriptive in nature, is designed for students with any B. s. Degree, who are interested in astronomy. The RTU has taken undisputed leadership in the Field of Space Education in the country. Hence, on the first semester of SY 2007-2008, A 5-yr Bachelor of Science in Astronomy Technology will be offered in the said University. The course will introduce astronomy the younger people who will make science and technology their lifetime careers. The designed course is customized to be white in scope where research and observation will be given priority, to push the frontiers in these fields at least in the Philippines for the meanwhile. In PAGASA, the personnel of the AsDRS who are performing all the previously mentioned astronomical the world activities do not have a formal education in astronomy. The knowledge Now you will ask me in astronomy that they possess is obtained through the infrequent in-service training courses conducted by the agency and through the books that were procured, usually from overseas sources. The Chief of AsRDS, undertook a course on Astronomy and Astronomical Observational GAO in 2001. Seven (7) personnel also participated in the International School for Young Astronomers (ISYA). Three of them attended the ISYA held un Thailand in 2001 while the remaining four are attending the course, which is presently being held in Malaysia. The signing of the Memorandum of Agreement between the IAU/TAD and PAGASA in 2002 led to the conduct of the Astronomers Training Course in the agency in 2003. Five (5) visiting lecturers of the IAU delivered lectures on various topics. PAGASA is still waiting for the availability of a lecture if you lecturer to complete. Three (3) astronomy personnel are also presently pursuing and M.Sc. degree in Astronomy at RTU. They are expected to finish the course in 2009. An AsRDS and personnel is also presently completing a course on space science in India with a research topic on variable star photometry. In the last quarter of 2007, another personnel of the astronomy section will undergo and On-the-Job Training on Outreach and Astronomical Research Activitiesat GAO. The activity will be made possible by a cooperation between IAU/TAD, GAO and PAGASA. Given the preceding information on the past and present resources, activities and educational in astronomy in the Philippines, it is not difficult to make a projection of the status of the science in the near future. In 1996, it was foreseen that, in the next decade, the development of astronomy in the country will remain as lethargic as it has been for the past four decades, unless drastic positive changes were implemented. With the successful implementation of some of the revitalizing activities that were planned in 1997, particularly the installation of the donated 45-cm telescope and the enhancement of astronomical knowledge in astronomy of the PAGASA personnel as well as other astronomy enthusiasts, the Filipinos can always hope for a better and brighter future for astronomy in the Philippines. Rizal Technological University To date, Rizal Technological University offers a 5 year Bachelor of Science in Astronomy Technology, a Graduate Diploma Course in Astronomy, and Master of Science in Astronomy. Since its existence it deliver scientific perspective to enhance astronomy in the country.  CHAPTER 3 EARTH, MOON AND SUN SYSTEM Chapter Objectives: 1. Evaluate the Earth, Moon, and Sun System 2. Differentiate the formation of Earth and Moon 3. Describe how Earth’s movements affect season 4. Explain solar and lunar eclipses 5. Describe the phases of the moon and its reason for occurrences INTRODUCTION Astronomy makes unexpectedly large contributions to formal and informal science education. Astronomy is the study of everything in the universe beyond Earth's atmosphere. That includes objects we can see with our naked eyes, like the Sun , the Moon , the planets, and the stars. In this chapter, we are going to study and evaluate the earth, moon and sun system, describe how earth movements affect seasons, Study the phases of the moon and differentiate the solar and lunar eclipse. THE EARTH SYSTEM In the discovery of the radioactivity also provided the means to determine the age of the earth. Though isotopic dating of meteorites, it has been shown that they are between 4.5 and 4.6 billion years old. Since Earth’s formation approximately 4.6 billion years ago, from a nebular cloud of dust and gas that surrounded the sun. As the gas cooled, more solids formed. The dusty material accreted to the nebular midplane where it formed progressively larger clumps. Eventually, bodies of several kilometers in diameter formed; these are known as planetesimals. The largest planetesimals grew fastest, at the expense of the smaller ones. This process continued until an earth-sized planet had formed. Barth surface is constantly changing because the earth looks very different today from how it looked millions of years ago.  Early in its formation, the earth must have been completely molten. The main source of heat at that time was probably the decay of naturally occurring radioactive elements. As the earth cooled, density differences between the forming minerals caused the interior to become differentiated into three concentric zones; the crust, mantle and core. Earth has been around a long time as well as with the Sun and the other planets in the solar system. In the beginning, the planet was so hot that the entire surface was a sea of liquid rock. As it cooled, the crust began to form. Pieces of the thin crust began to float on the molten rock volcanoes erupted, and continents began to grow. Water accumulated on the surface, and the oceans grew larger. SIZE, SHAPE AND MOTION Earth is the largest of the terrestrial planets. Earth has an estimated 5,9736 X 10kg. Its volume is also the largest of these planets at 108.321 X 1019 km³. Earth’s circumference is 24, 901.55 miles (40, 075.16km). It is slightly smaller between the North & South poles at 24, 859.82 miles (40, 008 km). Earth’s diameter at the poles is 7,899.8 miles (12, 713.5km) while it is 7,926.28 miles (12. 756km) at the equator. Chemically, the earth is composedof the following elements: Earth is not really a perfect sphere. The earth’s circumference and diameter differ because it bulges in the center or Elements Percentage around the equator. This bulging effect Iron 34.6 is due to the rotation of the earth, and Oxygen 29.5 with this bulge the earth is described as Silicon 15.2 having a shape of oblate spheroid. Magnesium 12.7 The bulging around the equator would then finally form a flattened surface along Nickel 2.4 the poles. It is measured at 26.5 miles Sulfur 1.9 (42.72km) and is caused by the Earth’s Titanium 0.05 rotation and gravity. According to Tiller (2005) there are three motions that are independent of motions of the Sun and the galaxy: (1) ayearly revolution around the sun, (2) a daily rotation on its axis, and (3) a slow clockwise wobble of its axis. THREE MOTIONS OF EARTH Earth has three different kinds of motions: Rotation, Revolution and Precession. Rotation is the movement of the earth as it rotates from west to east on its axis. The earth's rotation appears to rise from the east and moves to west. The earth's rotation appears to rise from the east and moves to west. One complete rotation took 24 hours, approximately 12 hours of daylight and 12 hours of nighttime. The Earth tilts at an angle of 23.5° at the North Pole and consequently the same with the South Pole the Earth's rotation can be measured in two ways:  Mean Solar Day- is the time interval from one noon to the next noon day, because it is the time when the sun has reached its highest point in the sky.  Sidereal Day - is the time takes for the earth to make one complete rotation with respect to a star other than the sun. In which, in a sidereal measurement, the earth rotates 360° in 24 hours, or 15° per hour. The evidence of a moving earth comes from at least three different observations: 1. The observation that the other planets and the sun rotate. 2. The observation of the changing plane of a long, heavy pendulum at different latitudes on earth. 3. The observation of the direction of travel of something moving across, but above, earth’s surface, such as a rocket. Revolution is one complete orbit of the earth to the Sun, in about 365,25 days. The direction of revolution counterclockwise as viewed down from the north. The earth is orbiting slightly elliptical, it moves at a speed of about 100,000 kilometers per hour, or 27.78 kilometers per second. The average distance between earth and the Sun is about 150 million km. The Earth’s orbit can be classified into two ways: Perihelion is the point, in which the earth is closer to the sun, and it is the time where the earth moves fastest, this usually happens during summer season.Aphelion it is where the point, in which the earth is farthest to the sun, and it is the time where the earth moves slowest, this usually happens during the rainy season. Precession is the reaction of earth to the gravitational pull of the moon and the sun on its equatorial bulge, however, these results in a slow wobbling of the earth as it turns on its axis. Precession is the slow wobble of the earth’s axis which causes it to swing in a slow circle like the wobble of a spinning top. The generally constant inclination and orientation of the axis, together with the earth’s rotation and revolution, combine to produce three related effects: (1) days and nights that vary in length, (2) changing seasons, and (3) dimates that vary with latitude. SEASONS, SOLSTICE AND CLIMATE Solstice is either of the two moments in the year when the Sun’s apparent path is farthest north or south from the earth’s Equator. The name is derived from Latin solstitium (from sol: “sun” and sistere: “stand still”). In the Northern Hemisphere summer solstice occurs on June 21 or 22 and the winter solstice on December 21 or 22. The situation is exactly the opposite in the Southern Hemisphere, where the seasons are reversed. During winter, solstice, the day is the year's shortest, and during summer solstice, it is the years longest. The position of the sun seen from the earth moves north and south and the changes in direction stands still momentarily, so solstices are those moments of the year when the sun reaches its southernmost or northernmost position, at the Tropic of Capricorn or Tropic of Cancer. Equinoxes are the days in which there are exactly 12 hours of daylight and 12 hours of night time everywhere in the world.. There are two kinds of equinox: 1. Vernal equinox (Spring equinox) - marks the beginning of spring in the Northern Hemisphere, occurs about March 21, when the Sun moves north across the celestial equator. 2. Autumnal equinox - which falls about September 23, as the Sun crosses the celestial equator going south. Note thatin June the North Pole is in sunshine all day, therefore, at the South Pole, the sun never rises. In December, the North Pole receives no sunshine; therefore, the South Pole receives sunshine all day. THE MOON SYSTEM The Moon has fascinated humans since the dawn of time. It is our nearest satellite, and has the distinction of being the only other world where humans have walked. The Apollo 11-17 mission in 1959 took astronauts to the Moon. They spent time doing scientific studies of the Moon’s surface. They brought back a treasury of rocks and due that helped researchers understand the origin and evolution of our closest natural satellite. It is about 3,476 kilometers in diameter, slightly more than the diameter of Earth. The Moon has no significant atmosphere, just a trace of hydrogen, helium, neon, and argon atoms, along with other traces in even lesser quantities. It is made of solid rock. It has a mass of only 1/81 the mass of Earth, and its density is about 3,3 times the density of water, which is less than the density of Earth. PHASES OF THE MOON The Moon’s appearance in our skies changes over time. Those changes are called lunar phases, and they occur over a period of twenty-nine and a half days, beginning with New Moon and going through quarter moon, slim crescent, and Full Moon before returning to New Moon again. The Moon orbits Earth once every twenty-seven days, and it always shows the same face to us. This is because it is locked into synchronous rotation, which means that it takes as long to rotate once on its axis as it does to orbit Earth.New Moon is the beginning of the monthly lunar cycle, or lunation. At this time, the near side faces away from the sun, making it the dark side. A few days later, the Moon is a new crescent, or waxing crescent, meaning a crescent moon whose bright are is getting larger. This phase happens as the moon moves away from the sun earth line while orbiting Earth. Fully half of the moon is always lit up, facing the sun, but during a crescent moon, we can’t see most of this illuminated area that faces away from Earth. As the Moon moves around its orbit, it reaches a point where the Earth-Moon line is at right angles to the Earth-Sun line. At this stage is the half-moon, or also known as quarter moon. When illuminated part of the Moon that we can see grows larger than the quarter (half) Moon and smaller than the full Moon, which is waxing gibbous Moon. When the Moon is on the far side of its orbit, opposite the Sun in the sky, the lunar hemisphere that faces Earth is fully lit, creating full Moon. As the moon continues around its orbit, the illuminated portion gets smaller and the moon becomes gibbous again, less than full and more than a quarter Moon (a waning gibbous Moon). Soon the Moon appears as a quarter Moon again, called last quarter. As the moon nears the line between Earth and the Sun, it becomes a waning crescent Moon. Soon it becomes a new Moon again, and the cycle of phases starts over.The total eclipse of the Moon occurs when it is immersed in Earth’s shadow. No direct sunlight falls on it, but some light from the sun gets bent around the edges of Earth’s atmosphere (as visible from the Moon) and falls on the Moon. The sunlight gets strongly filtered as it passes through our atmosphere, so mostly the red and orange light gets through. This effect differs from one lunar eclipse to the next, depending on meteorological conditions and the clouds in Earth’s atmosphere. The totally eclipsed moon. Therefore, can look a dull orange, an even duller red, or a very dark red. THE SURFACE OF THE MOON When we look at the Moon, it shows dark and light areas. Those dark areas are often referred to as maria(pronounced as may yah), the plural form of the Latin word mare, which means “sea” Early Moon watchers thought those regions were watery oceans, but a close look with a telescope or a pair of binoculars shows no water on the surface, just rocky plains. The low-altitude maria formed as volcanic vents called lunar domes emptied out their molten basaltic lava and flooded the surface. The light areas are called the lunar highlands, They are mostly hilly regions that lie at higher altitudes than the maria. The whole surface is peppered with impact craters, made as solar system debris crashed into the Moon. INSIDE OF THE MOON The Moon is primarily composed of basaltic rock. Because it lacks an atmosphere, or water on the surface, erosion (except erosion by impact of micrometeorites) is an insignificant process on the Moon. The history of the surface is preserved. The surface is covered with a thick layer of dusty material called regolith. Below that is the crust, and it's made mostly of a mineral called plagioclase, which is also found on Earth. The crust ranges in thickness from 60 to 150 kilometers. The interior of the Moon is solid. It has no molten core, and therefore is geologically dead. Quite sensitive seismology equipment, carried to the Moon by Apollo astronauts, detected vibration caused by tidal interaction with the Earth, and vibrations caused by impact from meteors, but no significant moon-quakes, which would indicate a geologically active core and allow the interior to be probed. Early Ideas on the origin of the moon. Until the mid-1980’s, the origin of the moon was a difficult issue for astronomers because the Moon is unusually large compared to Earth and moves in a circular orbit. A variety of theories, ranging from capture of a passing body by Earth’s gravity, to ejection of a chunk of matter by a rapidly spinning Earth, to information in place at the same time as had been suggested. Attempts to model the third theory, formation in place, with computers presents problems. The Moon’s density is consistent with little or no iron content. Capture of the Moon, while possible, is unlikely, and capture into a circular orbit is even more unlikely. Finally, there are problems with the physical plausibility of a molten Earth spinning rapidly enough to throw off the Moon. APOLLO’S CLUES AND NEW THEORIES Rock and dust samples brought back from the Moon by the Apollo missions in the 1980’s virtually eliminated all of the early theories. Although the Moon’s small size limits possible geologic activity, Moon rocks are more similar to Earth’s mantle than to meteorites like those that would have accreted to form the Moon. Moon rocks are also richer in silicates and poorer in metals and volatile elements than Earth’s rock. Simplistically put, Moon rocks could be made by heating rocks from Earth’s mantle until they vaporize, and then recompensing the less volatile materials. This geochemical mystery has prompted planetary scientists to consider a new theory that the Moon is the result of giant impact, a huge collision between Earth and another planet-sized body. How likely is such an impact? Early formation of the solar system. Conditions were right for this kind of collision. At first, accreting planetesimals would have been small and would have moved in roughly circular orbits. Collisions would have been gentle, largely, resulting in accretion. As planets grew larger, however, close passes of these bodies would have sent them into elliptical orbits, which in turn would increase collisions speed. By the time the terrestrial planets had formed, catastrophic collisions with the solar- system debris travelling in high speed elliptical orbits would have been likely. Small bodies hitting big ones would vaporized and melt, adding to the larger body. Big bodies hitting other big bodies would have had disastrous results. It was probably a giant impact the knocked Uranus on its side and spun out a disk from which its moons formed. THE GIANT IMPACT THEORY Computer simulations show that, if a planet as big as Mars, or slightly bigger, a big chunk of Earth’s mantle, but very little iron core, would have been spun off. Also, part of the material ejected would have entered a circular orbit, forming a ring around Earth. The rest of the ejected material would have recreated into Earth or been lost into orbit around the sun. The material ejected would have left a sizable hole, but the spinning of the still malleable Earth would quickly have restored the planet's normal shape. Most of the material ejected into space would have been vaporized, with only the least volatile materials remaining solid. Much of the volatile material (water and less dense ions) would be lost. This hypothesis is consistent with the lower density minerals with which rocks from the lunar highlands are enriched. Since little of Earth's core was ejected, little iron would be present. Material in the ring then collected to form the Moon. For the first billion years of its life, the newly formed Moon was bombarded by meteorites. They created great craters and melted the surface that is now the lunar crust. About a billion years into the Moon's life, accretion and radioactive decay produced enough heat to cause melting and differentiation in the upper 500 kilometers or so. Volcanoes erupted, pouring out huge floods of basalt, which now form the Maria. By about 3 billion years ago, the Moon had cooled enough that volcanic activity ceased. With the exception of few major impacts and small lava flows, the moon has remained virtually unchanged since then. The oldest rocks recovered from the moon date to 4.4-4.5 billion years ago, so it certainly didn’t occur any later. This age also sets a time by which Earth’s core must have formed. Formation of the core had occur before the impact that formed the Moon, because the Moon is poor in iron Most likely, the Moon formed early in Earth’s history, close to or before 4.5 billion years ago. INFORMATION ABOUT THE MOON  Origin of the moon - Formed from material thrown from a still liquid Earth following the giant object 4.5 billion years ago.  Craters - Largest craters resulted from an intensely bombardment by rock objects around 3.9 billion years ago.  Presence of water –Most dry, but water brought in by the impact of comets may be trapped in very cold places at the poles.  Age of rocks in terrae highlands - Most are older than 4.1 billion years; highland anorthosites (igneous rocks composed almost totally of feldspar) are dated at 4.4 billion years. \  Age of rocks in Maria Varies- widely from 2 billion to 4.3 billion years  Composition of terrae highlands - Wide variety of rock types, but all contain more aluminum than rocks of Maria plains.  Composition of Maria plains - Wide variety of basalt.  Composition of mantle - Varying amount mostly olivine ad pyroxene. THE SUN SYSTEM The Sun is a star and the biggest source of heat and light in our solar system. It's one of at least several hundred billion stars in the Milky Galaxy. Without it, life might not exist, and that makes it very important to us. To early people the Sun was something to worship. Ancient Greeks venerated Helios as the Sun God, but they had insatiable scientific curiosity about it. In 1600's, Italian astronomer Galileo Galilei speculated about what the Sun could be. So did Johannes Kepler a few decades later. In the 1800's, astronomers developed scientific instruments to measure the Sun's properties, which marked the beginning of solar physics as a scientific discipline. STRUCTURE OF THE SUN The Sun is essentially a big sphere of superheated gas. An imaginary voyage into its heart shows its structure. The Sun is so massive, it is approximately 330, 000 times the mass of Earth - that its powerful gravity can hold all the hot gas together. The hotter the gas, and the more gravity (or any other force) that squeezes it together, the higher the pressure. And gas pressure inflates the Sun, just like air pressure inflates an automobile tire. Gravity pulls in; pressure pushes out. At a certain diameter, the two opposite effects are equal and in balance, maintaining a uniform size. The certain diameter is about 1,391,000 km, or about 109 times Earth's diameter. That we could fit 1,300,000 Earths inside the Sun. The Sun is round because gravity pulls equally in all directions toward the center, and pressure pushes out equally in all directions. Since the Sun rotates at a very slow rate, every 25 days at the equator. The Sun has two main regions on the inside and three on the outside. The visible surface of the Sun is called the photosphere(meaning "sphere of light"). The inside of the Sun, the region below the photosphere is called the stellar interior. At its center is the core. In the heart of the core, nuclear fusion generates all the Sun's energy, and it releases it in the form of gamma rays, a very energetic type of light, and neutrinos, strange subatomic particles. The gamma rays bounce off one atom to another, back and forth, but on average move upward and outward. The neutrinos zip right through the whole Sun and flu out into space. The farther out in the solar interior; the cooler the temperature gets. At a distance of about 494,000 kilometers, the core gives way to the next major region, the convection zone. The Sun's convective zone has granular areas, like boiling a sugar syrup. The temperature of the convective zone drops from about 2.2 million °C at its center when it reaches the next region, the photosphere. It is the layer of gas that produces all the visible light of the Sun, except at the time of a total eclipse. The dark spots on the photosphere, sunspots, are the most easily observable solar features. Above the photosphere, the successive regions of the Sun gel hotter, not cooler. The chromosphere, or color sphere, is just above the photosphere. It about 1,600 km thick, but the temperature of the chromosphere reaches 10,000°C. Above the chromosphere is the corona a region so rarefied and electrified that the Sun's magnetics field determines its shape. There are loops which extend from the photosphere up into the corona and contain gas much cooler than the surroundings which are called prominences, which can be seen on the limb of the Sun during a total eclipse. THE SUN-EARTH CONNECTION The northern or southern lights occurs at the upper atmosphere light shows are actually a very benign form of space weather, it describes changes in the near-Earth space environment mainly due to activity originating at the Sun occurrences of aurorae at the north pole is called aurora borealis, while aurora austral is from the south pole. These aurora are upper atmosphere disturbance caused by solar activity. They occur about 80 to 90 kilometers’ above the polar regions of our planet. It is a connection between Earth and Sun more than the heat and light. When the Sun sends a huge blast of charged particles in a giant outburst called a coronal mass ejection, or blast out a giant X-class flare (the largest and most intense type of outburst), that material. rushes out at high speeds. Masses of charged particles arrive anywhere from one to three days later, and they collide with Earth's magnetic field and stir up activity in the ionosphere. A heavy solar outburst causes ionosphere disturbances called geomagnetic storms. These can affect or even shut down communications and global positioning satellites, endanger astronauts in near Earth space, and in some severe cases, shut down power grids on our planet.