EARTH SCIENCECHAPTER IAstronomy

LESSON 1: INTRODUCTION TO ASTRONOMY

History of AstronomyPlace Year Astronomical Contributions / Events

Southern England

1075 BC – 2800 BC

STONEHENGE – contains more than a dozen astrological alignments

- perhaps an astrological observatory

- used as calendar

America CARACOL TEMPLE – aligned where Venus rose and set

Asia ARTIFACTS – sketches on bones and stones such as phases of the moon

Egypt 2700 BC COFFIN LIDS –divided the stars of the equatorial belt into 36 groups ( 365 days + 5 days = 36 ten-day period)

Babylon 2000 BC LUNAR MONTH – measurement of time

1 Babylonian Year = 12 months

(stars of the zodiac, the 12

constellation / 30 days each)

1 week = 7 days named after moon,

sun & 5 planets

1 day = 24 hours

1 hour = 60 minutes

1 minute = 60 seconds

Mesopotamia 2000 BC

1000 BC

700 BC

400 BC

Venus returned to the same position 5 times in 8 years

Observations became relatively accurate and systematically recorded

Calculations of revolution of the visible planets

Accurate predictions of astronomical events like lunar eclipse

Developed an algebraic method of analysing the periodic phenomena in the sky but they did not use geometrical methods to interpret their observations

Ancient astronomical information was introduced by Greek astronomy based on the contributions of philosophers.

Philisopher Year Astronomical Contributions / Statements

Thales of Miletus

625 – 547 BC “Universe is rational and man can understand it.”

“The universe is not unknowable.”

He had correct prediction of solar eclipse.

Pythagoras

580 – 500 BC “Universe is divided into 3 parts – OLYMPUS,

COSMOS, URANUS / EARTH.”

“Earth is a sphere.”

“Stars, sun, 5 visible planets and moon are carried

by rotating sphere.”

Plato

428 – 322 BC “Universe is essentially mathematical and reality is

an optical illusion.”

He adopted Pythagoras ideas and added that

those astronomical bodies were spherical in

shape.

Aristotle

384 – 322 BC

“The rotating spheres are real physical bodies not

just geometrical constructions.”

“The universe is finite in size and divided into 2

parts – EARTH which is the center of the

universe and HEAVEN.”

“There are four terrestrial elements – EARTH,

WATER, FIRE and QUINTESSENCE, the purer

elements that are found in heaven.”

Astronomical Instruments

An important part of the science of astronomy is the use of astronomical instruments. An astronomical instrument generally refers to a type of equipment used for the study, observation, or measurement of celestial objects.

A telescope is an instrument that aids in the observation of remote objects by collecting electromagnetic radiation (such as visible light). The first known practical telescopes were invented in the Netherlands at the beginning of the 17th century, using glass lenses.

The word "telescope" (from the Greek tele "far" and skopein "to look or see"; teleskopos "far-seeing") was coined in 1611 by the Greek mathematician Giovanni Demisiani for one of Galileo Galilei's instruments.

Optical TelescopeAn optical telescope gathers and focuses light mainly from the visible part of the electromagnetic spectrum (although some work in the infrared and ultraviolet). It increases the apparent angular size of distant objects as well as their apparent brightness. There are three main optical types:

The reflecting telescope which uses an arrangement of mirrors to form an image.

The refracting telescope which uses lenses to form an image.

The catdioptric telescope which uses mirrors combined with lenses to form an image

Radio TelescopeRadio telescopes are directional radio antennas used for radio astronomy. The dishes are sometimes constructed of a conductive wire mesh whose openings are smaller than the wavelength being observed.

Space TelescopesSpace telescopes are placed above the atmosphere that can receive much sharper images. These can receive infra-red, ultra-violet and X-ray energy that cannot be received on Earth because of the atmosphere.

An observatory is a building specially designed to house telescope. It is built high up on mountain tops where it is above most of the pollution, dust and waste vapour in the atmosphere.

A rocket is a spacecraft that obtains thrust from a rocket engine. It lifts satellites, space probes and astronauts. A rocket propelled upwards by hot exhaust gases streaming from nozzles at the tail. These gases are the result

by burning a mixture of liquid oxygen and fuel (such as liquid hydrogen) inside the combustion chamber. Carrying its own oxygen supply enables the rocket engine to function in the airless vacuum of space. There are two types of rockets.

Space ProbesFly-bys are space probes lifted into space by rockets, which are computer-controlled robots packed with scientific instruments. It sent to fly by a planet or even orbit around it, sending data and images back to the earth. After they have completed their planned missions, some probes continue on into space.

A lander is a spacecraft which descends toward and comes to rest on the surface of an astronomical body. It is first a re-entry vehicle.

A rover (or sometimes planetary rover) is a space exploration vehicle designed to move across the surface of a planet or other celestial body. Some rovers have been designed to transport members of a human spaceflight crew; others have been partially or fully autonomous robots. Rovers usually arrive at the planetary surface on a lander-style spacecraft.

Mariner 2 was the first

successful fly-by mission outside the Earth- moon system which passed Venus

Lunar rover Mission to Mars – Mars Global Surveyor

Space Station is a large space craft designed to stay permanently in orbit. Crews live and work here for several months at a time.

International Space Station where scientists from different countries work together.

Space Travels and Space Explorations

ASTRONAUTS came from two Greek words astron and nautes meaning “star voyager”. These are people who fly on American space missions.

COSMONAUT means “voyager into the cosmos”. These are Russian who fly into the space.

Date Space Craft Astronomer / Animal

3 Nov 1957 Sputnik 2 LAIKA, a Russian dog that was the first living creature in space. Laika died in space

Aug 1960 Koralb – Sputnik 2 BELKA and STRELKA, 2 Russian dogs that were the fiert creatures to return to Earth after orbiting it for 24 hours.

April 1961 Vostok 1 YURI GAGARIN is the world’s first spaceman who was a Russian.

1962 Mercury Space Capsule JOHN GLENN, an American who first to orbit the Earth.

1971 Apollo 14 ALAN AHEPARD played golf on the moon.

LESSON 2: THE UNIVERSE

GALAXY is an enormous spinning cloud of gas and they continue to spin, the speed of rotation affects their shapes. LARGE GALAXY may have billions of stars. SMALL GALAXY may have a few hundred thousand-but not so big that it takes light thousands of years to cross.

BASIC TYPES OF GALAXIES

1. ELLIPTICAL GALAXY. This ranges from ball shaped to egg-shaped. It contains

3. BARRED-SPIRAL GALAXY. It is like the spiral galaxies, but the nucleus is elongated into a bar.

mainly old stars. And it is the most common type of galaxy

Its spiral arms extend from the ends of the bar.

2. SPIRAL GALAXY. This is disc-shaped galaxy. Most materials are in the spiral arms where new stars are formed. The old stars are in the nucleus.

4. IRREGULAR GALAXY. It does not fit any known pattern. It is the rarest type. Most of the stars here are young stats.

CLUSTER is group of a few to a thousand galaxies. Its average distance between galaxies in clusters is about 10 galaxy diameter. It is just small part of a giant supercluster. SUPERCLUSTER tends to be flattened into discs or sheets, at elongated into filaments. Its diameter is about 100 million ly.

LOCAL GROUP is our own group. Its diameter is about 5 million ly. It contains about 30 galaxies. And the largest galaxies in the local cluster are ANDROMEDA (M31), TRIANGULUM (M33) and our MILKY WAY GALAXY.

VIRGO CLUSTER-60 million ly away, major cluster to ours

MILKY WAY GALAXY is a spiral galaxy. Its nucleus is the brightest region and about 6 000 ly across. Nucleus has the old stars surrounded by a halo of even older stars. All the young stars, like the sun, are located in the spiralarms. Spiral arms contain most of the galaxy gas and dust and this is where star forming regions are formed. ORION ARM/SOLAR ARM is where the solar system is situated about 2/3 from the galaxy center, at the edge of a spiral arm.

Milky Way Galaxy rotates and 1 complete revolution is 220 million years COSMIC YEAR.

It takes 1000 000 ly to travel from the edge to edge. All stars we see as a great milky river of star across the clear night sky are in the Milky Way.

The side view of Milky Way Galaxy looks like a giant lens with flattened edges and a bright central nucleus. Around the nucleus is a roughly spherical halo.

STAR is enormous spinning ball of gas. Its two main gases are H and He, held together by gravity at the core and they are very densely packed. Within the core, immense amounts of energy are produced. All the chemical elements heavier than H, He and Li were made by nuclear reactions inside stars.

1 solar mass (mass of the sun) is used as standard for measuring the mass of a star.

STRUCTURES OF STAR 1. Energy is released at the SURFACE as light and heat. 2. Temperature and pressure increase towards and the CORE. 3. Energy is produced by nuclear reactions in the CORE.

NUCLEAR FUSION is a process by which star produced energy. Within the core, an H nucleus proton collide and fuse to form first DEUTERIUM, a heavy H and forms He. During fusion, energy is given off. This reaction, which found in most stars, is also called PROTON –PROTON CHAIN REACTION.

LIFE CYCLE OF STARSStars follow a life cycle that last millions and billions of years. All stars begin in the same way in as material in a NEBULA. Stars are not born individually, but in groups called CLUSTER. Initially, the stars in a cluster have roughly the same composition. Despite these early similarities, the stars usually develop at different rates and most clusters drift apart before very long.

STELLAR BIRTHPLACEIn the Orion nebula light from new stars illuminate the dust clouds. The stars themselves remain hidden by the dust.one of these young stars is 10 000 times brighter than the sun.

FORMATION AND EARLY DEVELOPMENT OF A STAR 1. Inside the NEBULA, gravity causes spinning balls of gas to form PROTOSTAR.2. The protostar shrinks and its core become denser.an outer halo of gas and dust develop.3. When the core reaches its critical density, nuclear reactions start. The energy released blows away most of the halo.4. As the young star continues to spin rapidly, the remaining gas and dust become flattened into a disc.5. The disc of gas and dust has formed into a system of orbiting planets our solar system.6. With or without planets, the new star now shines steadily, converting H to He by nuclear fusion.

CONSTELLATION is a pattern formed by the stars seen in the sky. It is a flat pattern against the blackness of space but in fact the stars may be farther in distance from each other than they are seen from earth. The skies around the earth have been divided into 88 different constellations. It is a human invention

IMPORTANCE OF CONSTELLATION1. once helped people sail ships and make calendars2. help one learn his way around the sky

EXAMPLES OF CONSTELLATION1. ORION THE HUNTER climbs into the northern January sky. The 3 stars of Orion’s belt point down to SIRIUS, the sky brighter sky .rising through the trees 2. BIG DIPPER Is a pattern of seven stars of URSA MAJOR, the Great Bear. In Great Britain this pattern is known as the PLOUGH, German call it GREAT WAGON and THREE HORSES3. LEO AND LIONpeople have seen Leo as a starry lion since ancient times. The 6 bright stars

that look like a backward question mark trace out lions head.leo is one the 12 constellation of the zodiac

4. SCORPIUS THE SCORPION is the mortal enemy the Orion. These mortal enemies are opposite each other in the sky as one raises, the other sets. Scorpions is another constellation.

LESSON 3: THE SOLAR SYSTEM

INPUT

The whole solar system moves through space. The planets follow elliptical orbit, all moving in the same direction but at different speeds. Each planet also spins on its axis.

LIGHT from the sun reaches the Earth in 8 minutes.

ORBIT is an elliptical imaginary pathway where planets revolve around the sun. it has two parts; (1) PERIPHELION – part of the orbit nearest or closest to the sun, where planets move faster and (2) APHELION – part of the orbit most distant to the sun.

BIRTH OF THE PLANETSThe solar system was born from a swirling cloud of gas and dust. About 5 million years ago, the cloud began to shrink. Under the force of gravity, most of the materials fell toward the center of the cloud.

Gas collected there, heated up and became the sun. Dust and gas left over in the cloud formed the planets.

1. CLOUD OF DUST AND GAS SHRINK. Perhaps a nearby star explodes and squeezes the cloud like a snowball. The cloud starts shrinking. The sun forms

2. CLOUD BEGINS TO ROTATE. As it shrinks, the cloud begins to spin like a hurricane. It speeds into a flat disc around the new sun.

3. DUST IN DISC FORMS ROCKY LUMPS. The dust particles in the disc begin to stick together and form billions of lumps of rocky materials.

4. ROCKY LUMPS COLLIDE. The se rocky lumps smash together and form thousands of objects as big as small planets

5. THE SOLAR SYSTEM TODAY.The small planets collide for millions of years until only few are left. These are the planets we know today, including mysterious Pluto.

SUN is an average yellow star. It is a medium – size star. It is middle – aged star. Like most other stars, it is a hot, glowing sphere of virtually pure H gas held together by gravitational attraction

FACTORS AFFECTING TEMPERATURE AND DENSITY OF THE SUN1. The specific process by which solar energy is generated. The source is the THERMONUCLEAR

TRANSMUTATION of H to He. Since H constitutes most of the sun’s mass, and since each creation of a He nucleus liberates a huge quantity of energy, the process is adequate to the sun’s energy requirement.

2. The process by which energy is transported to the surface.a. RADIATION – energy is transported most easily by radiation at the high temperature of the

solar interiorb. CONVECTION – convection assists radiative transport in 2 regions in the interior, inside a

small central core and in a shell lying just below the photosphere. H plays secondary role.c. CONDUCTION – it seems to play no important role whatever

3. The chemical composition of the interior

HELIOSEISMOLOGY – study of sun’s vibration

PLANETS are smaller bodies than the sun that revolves around it because they are captured by its gravity

CLASSIFICATIONS

A. Based on CompositionsB. Based on Size

1. TERRESTRIAL / ROCKY PLANETS

Mercury – smallestVenusEarthMars

2. JOVIAN / GASEOUS PLANETS

Jupiter – biggest

Saturn Uranus

Neptune

C. Based on Location (Asteroid Belt)

1. INNER PLANETSMercury – innermostVenusEarthMars

2. OUTER PLANETSJupiter

Saturn

Uranus

Neptune – outermost

D. Based on Human’s Capability to be Seen

1. Planets that can be seen with the naked eyes because they shine brightly in our sky

Mercury Jupiter

Venus Saturn Mars

2. Planets that lie far from the sun that you need binoculars or even telescope to see them

Uranus

Neptune

MERCURY is a small rock world with a large dense core. It is named after the fleet-footed messenger of the Roman gods because it travels so quickly across the Earth’s sky. It has no real atmosphere; its atmosphere is extremely thin - > 1 trillionths of Earth’s. Na & K are present in the daytime only, at night these elements are absorbed into the surface rocks.

Dominated by sun, Mercury experiences the greatest variation in surface temperature of any planet in the solar system. It has a relatively weak magnetic field indicating that part of the magnetic core is still fluid. It rotates very slowly on an almost upright axis tilted at just 2º.

It can only be seen from Earth at twilight – dawn or just after sunset.

VENUS is a rock planet with a dense atmosphere, which is almost the same size as the earth.

It spins backward compared to the other planets; perhaps a giant asteroid hit Venus and flipped it upside down. Driven by powerful winds, its atmosphere moves at its own in a much faster pace. Overhead are thick clouds of sulfuric droplets.

MAAT MONS is an extinct volcano about 8 km high.

Two large continent – like areas rise above the average surface1. ISHTAR TERRA 2. APHRODITE TERRA - twice as large as Ishtar Terra

EARTH. The name Earth came from the Anglo – saxon word earthe meaning “land”. Its axis of rotation is tilted at 23.5º that causes seasonal variations in climate. It has a much stronger magnetic field than any of the other rock planets produced by the rapid rotation of the nickel – iron core that produced magnetic field called magnetosphere.

Wind and rain have worn away most of Earth’s impact craters. If Earth had no atmosphere to create weather, it would have as many craters as the moon. It has the range of temperature that permit liquid water to exist and has developed an oxygen rich atmosphere – enabled the rocky planet to evolve the myriad varieties of life.

Its atmosphere acts like a huge solar – powered engine, transporting and redistributing water around the planet as clouds and rain. The oxygen in the atmosphere is the result of life. The process of oxygenation began with bacteria about 2 000 million years ago.

EARTH’S MOON is the only satellites of the Earth which is about one quarter the size of our planet. It is waterless, airless and lifeless place. It is covered with Maria and craters. MARIA is a Latin word the means “seas.” But Maria on the moon has never been filled with water. They are actually flat plains of ancient lava’

Its battered surface is covered by craters, from the Greek word krater meaning “bowl.” These scars of a massive meteorite bombardment that took place billion years ago. Most of the craters were made about 3 000 million years ago, and are only faintly visible. Some newer craters are identifiable by conspicuous rays of pale ejected materials fanning out from the crater wall. Approximately, has the same surface area as the continents of North and South America.

The pull of the Moon’s gravity is largely responsible for the twice daily rise and fall of tides in Earth’s seas and oceans

PHASES OF THE MOONThe moon appears to change its shape because as it travels around us, different amounts of the face we see are hit by the sun. When the moon comes between us and the sun, the near side of the moon – the side that faces us – is dark. This phase is called NEW MOON. Two weeks later, the moon has moved halfway around its orbit. Now the near side is completely lit by the sun and we see a FULL MOON. The moon takes past over

29 days to go from New Moon to New Moon.

1. NEW MOON. The side of the moon facing us is dark. This phase is invisible. 2. WAXING CRESCENT. You can see this phase in the western evening sky just after New Moon3. FIRST QUARTER. Look high in the evening sky as the sun sets in the west4. WAXING GIBBOUS. This moon is in the early evening sky 9 to 12 days after New Moon5. FULL MOON. This bright moon rises in the east just has the sun sets in the west.6. LAST QUARTER. This moon rises after midnight. It is high in the sky at dawn7. WANING CRESCENT. Get up early to see this moon. It is low in the east at dawn.

MARS is a red-hued rock planet; the red color is caused by the presence of iron oxide.

VALLES MARINERIS is the largest of the Martian canyons, has a length of about 4 500 km and a maximum depth of 7 km.

THARSIS is Martian volcanic area.OLYMPUS MONS is a giant shield volcano and the tallest mountain in the solar system that towers

25 km high.

MARTIAN MOONS1. PHOBOS is the inner moon that is a potato –

shaped and 27 km long. It orbits Mars at a distance of 9 380 km every hours and 40 minutes.

2. DEIMOS is the outer smaller and darker moon that is only 15 km long, no bigger than a small city. It orbits Mars at a distance of 23 462 km and taken about 30 hours to circle the planet.

Both are irregularly shaped and have every appearance of being asteroids that were captured by Mars’ gravity. Phobos means “fear” and Deimos means “terror” – suitable companions for the planet named after the god of war.

JUPITER is the largest of the planets, has 2 ½ times more mass than all other planets together. It has strong magnetic field (15 times stronger than that of the Earth) because of (1) its rapid rotation and (2) its fluid metallic interior. It does not have solid surface.

GREAT RED SPOT is the most prominent feature of Jupiter which is a gigantic rotating storm bigger than the Earth. It spins like a hurricane in the clouds that can last at least 300 years.

JUPITER’S REMARKABLE SATELLITE 1. METIS is the innermost moon of Jupiter, zips around the planet

so quickly that it could cross North America in just 2.5 minutes2. AMALTHEA is an irregular, cratered object which is the largest of

the 4 inner moons. Its dark surface is very red, probably contaminated by sulfur from Io.

THE GALILEAN MOONSFour of Jupiter’s moons are bigger than Pluto. The astronomer Galileo discovered these four giant

moons in 1610, acquiring the name Galilean moons.

1. Fiery IO is a world of volcanoes . This is about 20 times faster than materials from volcanoes on Earth. Its interior is still molten and has the first

active volcanoes to be discovered outside the Earth. Volcanoes not only erupt with molten rock but they also pour liquid sulfur over the surface. The sulfur cools and hardens into a wildly colored crust of yellows, oranges and reds. Some people think that this moon looks like a pizza

2. Icy EUROPA is covered by a smooth layer of solid ice. It has sufficient internal heat to have seas of liquid water lying beneath its featureless surface – perhaps the only other ocean in the solar system beyond Earth.

3. Gigantic GANYMEDE is the biggest moon in the solar system larger than the planet Pluto and Mercury. It is twice as large as Pluto and bit larger than Mercury. It is so big that if it orbited the sun instead of Jupiter, we would call it a planet. It is believed to consist mainly of ice and slush. It may have a silicate rock core.

4. Cratered CALLISTO has thousands of craters covered with cracked and dirty ice around a rock core. It is scared by many craters, VALHALLA being the largest with a diameter of 3 000 km. Apart from the occasional impact of a comet, this cold moon has hardly changed for billions of years.

SATURN is the second largest planet in the solar system. It is famous for its magnificent ring system. Its atmosphere is very similar to Jupiter’s but it is colder. Its cloud layers are much thicker and have muted bands. Rotating storms shaped by powerful jet stream show cyclonic activity in Saturn

SATURN RING WORLDSaturn’s rings are a blizzard of snowballs. From a distance, the rings look solid, but from close-up, you would see they are made of billions of ice chunks the size of hailstones and snowballs. If you could pack all the ring particles together, you could make a single giant snowball about 100 km across the size of a small moon of Saturn. The rings consist of billions of ice-covered rock fragments found in the inner rings closest to the planet, while fine dust accumulates in the outer rings.

SATURN’S RING SETS1. RING A – outer ring2. RING B – most prominent middle ring3. RING C – faint ring often referred to in the past as the CREPE RING

Saturn has 18 moons, one is very large, seven are of average size and the rest are small and irregular shaped. Some of the small moons are co-orbital, both a pair and a triplet that is they share an orbit with another moon. (HELENE & DIONE / TETHYS, TELESTO & CALYPSO – Saturn is the only planet that has 3 moons sharing the same orbit). In addition, 2 other moons, JANUS & EPITMETHEUS, have orbits that are extremely close to each other. Astronomers believe that these 2 were once a single moon that broke up. Most of Saturn’s moons are named after members of the titans, a family of Greek supergods ruled by the giant Titan.

URANUS is seventh planet from the sun. It is a cold gas giant.

Eleven rings encircle Uranus. These are composed of some of the darkest material yet observed in the solar system. Rings are composed of rock fragments about 1 m. There are bright dust lanes between

dark lines. The outermost Uranian ring has no fragments less than 20 cm and sharply defined. Little surface detail can be seen, and even close – up pictures of Uranus show only a few clouds of frozen methane gas. Its atmosphere is dominated by methane giving the planet a bluish appearance.

NEPTUNE is the outermost of the gas giant. It is a near twin to Uranus. It is too faint to be seen easily from Earth. It was first observed in 1846 exactly where it was predicted to be.

Methane in its atmosphere gives it deep blue coloration. It radiates 2.6 times more heat that it receives from the sun – a sign of an internal source of heat. Far too distant from the sun for the tilt to result in a similar cycle of seasons as that of Uranus. Its high – altitude cirrus clouds of frozen methane crystals are situated

about 40 km above the main cloud layer. And its dark low – altitude clouds of hydrosulfide.

Its atmospheric conditions are dominated by winds blowing at op to 2 000 km / s which carry the dark storms around the planet. The highest level of the atmosphere contains a thin hydrocarbon haze.

GREAT DARK SPOT is the largest storm on Neptune which is about the same size as Earth. It rotates in an anti – clockwise direction.

OTHER HEAVENLY BODIES

METEOROID

COMET ASTEROID

1. A comet is an icy small Solar System body that, when passing close to the Sun, heats up and begins to outgas, displaying a visible atmosphere or coma, and sometimes also a tail. It has its own orbit around the sun. It is also known as dirty snowball. It has three parts; (1) central NUCLEUS, (2) COMA – the central atmosphere immediately surrounding the nucleus and (3) TAIL – may be a gas or a dust.

2. Asteroids are minor planets, especially those of the inner Solar System. The larger ones have also been called planetoids.

3. A meteoroid is a small rocky or metallic body travelling through space. Meteoroids are significantly smaller than asteroids, and range in size from small grains to 1 meter-wide objects.

4. A meteorite originates in outer space as a solid piece of debris from such sources as asteroids or comets that survives its impact with the Earth's surface. It is called a meteoroid before its impact.

Meteorites have traditionally been divided into three broad categories: stony meteorites are rocks, mainly composed of silicate minerals; iron meteorites that are largely composed of metallic iron-nickel; and, stony-iron meteorites that contain large amounts of both metallic and rocky material.

5. A meteor shower is a celestial event in which a number of meteors are observed to radiate, or originate, from one point in the night sky. These meteors are caused by streams of cosmic debris called meteoroids entering Earth's atmosphere at extremely high speeds on parallel trajectories. Most meteors are smaller than a grain of sand, so almost all of them disintegrate and never hit the Earth's surface.