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CP Space Science Unit (Textbook reference Chapters 12, 13, 14, 15 and 16) 1 Key Ideas • Galaxies: clusters of stars; different shapes • Stars: Sun; differ in size, temperature and color; source for all bright objects • Gravity: planets, stars, solar system • Know the appearance, composition, position and size, and motion of objects in our solar system • Astronomical units for measuring 2 What is astronomy? What is a Meteor? What is a Star? ? ? ? What is an Open Cluster? What is a Nebula? What is a Comet? ? ? ? What is a Quasar? What is a Black Hole? M33, The Pinwheel Galaxy in Triangulum by George Greaney What is astronomy? M33, The Pinwheel Galaxy in Triangulum by George Greaney Basically, if its off this planet its a study of some realm of astronomy. As one might imagine that covers an awful lot of subjects, even more than we know right now. •NGC 253, galaxy in Sculptor What is astronomy? Astronomy is a science that attempts to understand the make-up and the M83 in Hydra history of the universe.Galaxy by George Greaney •Stars •Nebula •Planets •The Sun •The Great Andromeda Galaxy by George Greaney •Star clusters •Galaxies •Galaxy clusters •Dark matter •Black holes What is an astronomer ? Galileo Galilei (1564-1642) A night watchman with a college education? An astronomer is a scientist, skilled in mathematics, physics, and astronomy. Most professional astronomers work for universities or government agencies. Galileo Observatory in Italy Source: The Berkeley Cosmology Group Few astronomers spend much time looking through a telescope. Most operate telescopes from a control room or even from their computer at home via the Internet. Typical astronomers only spend one or two weeks each year observing, and the rest of their research time analyzing their data. Source: Applied Theoretical and Computational Physics Division Los Alamos National Laboratory Astronomer Serena Kim at work At Cerro Tololo in Chili What is an amateur astronomer? Amateurs and their tools What is an amateur astronomer? Although the term has different meanings for different people, a basic definition would include anyone who looks into the sky, and wants to see or learn more. What is astronomy ? Reflection nebula IC4606 by George Greaney The Expanding Universe 15-5 Theories on How the Universe Formed • The Big Bang Theory • Steady-State Theory and Plasma Theory Hubble’s Law Age of the Universe 15 What is space like? • No air • No gravity-when you’re not very close to a planet, sun, or moon • No wind • No friction • No real “up” or “down” • No pressure What is a “galaxy”? (15.4 Textbook reference) • A large group of stars outside of our own Milky Way • Made of billions to trillions of stars – Also may have gas and dust • Spiral, or elliptical, or irregular shaped Image at http://hubblesite.org/newscenter/archive/releases/galaxy/spiral/2007/41/results/50/ Spiral galaxy--Andromeda NOAO/AURA/NSF Images at http://www.noao.edu/image_gallery/html/im0606.html and http://www.noao.edu/image_gallery/html/im0685.html Elliptical Galaxies Images at http://hubblesite.org/newscenter/archive/releases/galaxy/elliptical/2007/08/image/a/format/large_web/results/50/ and http://hubblesite.org/newscenter/archive/releases/galaxy/elliptical/1995/07/results/50/ Irregular Galaxies NASA and NOAO/AURA/NSF Images at http://hubblesite.org/newscenter/archive/releases/galaxy/irregular/2005/09/results/50/ , http://www.noao.edu/image_gallery/html/im0560.html , and http://www.noao.edu/image_gallery/html/im0993.html Our Galaxy: the Milky Way • has about 200 billion stars, and lots of gas and dust • is a barred-spiral (we think) • about 100,000 light-years wide • our Sun is halfway to the edge, revolving at half a million miles per hour around the center of the Galaxy • takes our Solar System about 200 million years to revolve once around our galaxy The Milky Way Image at http://news.nationalgeographic.com/news/bigphotos/1945371.html Mapping the Milky Way How do we know what our galaxy looks like? We can see – stars – star clusters – nebulae – galaxies Reviewing Galaxies • Groups of stars, planets, and space debris • Irregular, Elliptical, Spiral • Milky Way is our galaxy 24 15.3 Lives of Stars 25 What Is a Star? Image of the Sun from Goddard Space Flight Center What is a Star? Our Sun is the closest star. At the simplest, a star is just a ball of gas that has condensed out of interstellar material. The largest part of its lifetime is spent as a main sequence star during which hydrogen is being converted to helium balancing gravitational contraction so that the radius and energy output remain almost constant. Source: The British Astronomical Association Stars (Textbook reference 15-2 and 15-3) • Bodies of gases that give off tremendous amounts of radiant and heat energy • Constellations are groups of stars used for navigation, storytelling, honoring heroes Life Cycle of a Star Video 28 Nearby Stars: Name Distance from Earth Sun 93 million miles (8 light minutes) Proxima Centauri 4.22 Light Years Alpha Centuri A,B 4.39 Light Years Barnards Star 5.94 Light Years Wolf 359 7.8 Light Years Lalande 21185 8.3 Light Years Sirius A,B 8.6 Light Years Image courtesy of Dave Dockery Astronomical Society of Las Cruces Source: The British Astronomical Association Evolution of Stars 30 How do Black Holes form? 31 Black Holes • Remains of a neutron star that has collapsed due to intense gravity • Event horizon = surface of a black hole from which light cannot escape 32 15.2 Characteristics of Stars • Star sizes – White dwarf, Medium, Large, Giant Star • Spectrograph – Device that breaks light into colors and produces a light emmissions spectrum. • ROYGBIV – Low energy to High energy – Red, Orange, Yellow, Green, Blue, Indigo, Violet • Light Year – Light travels at 300,000 km/second – Distance light travels in one year (9.5 million million km. 33 Hertzsprung-Russell Diagram Video on the Hertzsprung-Russell Diagram The Doppler Effect: Spectroscopy Video Red Shift – stars moving away from Earth Blue Shift – stars moving toward Earth 34 Hertzsprung-Russell Diagram Images from http://www.nasa.gov/centers/goddard/news/topstory/2007/spectrum_plants.html and http://sunearthday.gsfc.nasa.gov/2009/TTT/65_surfacetemp.php Using a Star’s Spectrum • We can use a star’s spectrum to classify it. NOAO/AURA/NSF image at http://antwrp.gsfc.nasa.gov/apod/ap010530.html Time to Create a Stellar Graph • Everyone will receive several “stars” • Place them on the large paper, according to their color and their brightness • This is a version of the Hertzsprung-Russell diagram. Measuring Distances • Parallax – apparent change in position of an object when you look at it from a different position. • (let’s model it) – As Earth orbits the Sun, we see nearby stars move relative to more distant stars – How many degrees did the plate move, relative to the background? – Can you calculate the distance to the plate? – The angles involved for stellar observations are very small and difficult to measure. Proxima Centauri, has a parallax of 0.77 arcsec. This angle is approximately the angle subtended by an object about 2 centimeters in diameter located about 5.3 kilometers away. The Sun (Textbook reference 14-2 • The sun is an ordinary star. • The sun is the biggest, brightest, and hottest object in the solar system. • Its energy is the result of the fusion of hydrogen nuclei into helium nuclei. • The sun is made of about 70% hydrogen and 28% helium. Characteristics of the Sun • Interior: Core, Radiation Zone, Convection Zone • Exterior: Photosphere, Chromosphere, Corona • Features: Sunspots, Prominences, Solar Flares • Central star in our solar system around which planets revolve • Composed of gases (H2 and He) burning at 15,000,000 o C 40 The Sun: Seasons (Textbook Reference 12-1) Seasons: Solstices sun directly overhead two times a year (June 21 and December 21) June=longest day, December=shortest day Equinoxes halfway between solstices neither hemisphere is tilted toward the sun daylight and darkness=equal 41 What causes the seasons? 1. 23.5° tilt of Earth’s axis 2. Direct vs. indirect sun rays 3. Length of daylight 42 Fall Summer Sun Winter Spring 43 The Sun: Solar Energy (14-2) Energy in the Atmosphere: Energy reaches earth’s atmosphere Reflected back or absorbed clouds, dust and gases surface Energy is transferred within the troposphere radiation: heats land and water reflected back into atmosphere convection: moves heat through the troposphere warm air is replaced by denser, cool air conduction: transfers heat from land and water directly into the air nearest Earth’s surface 44 Our Sun is a star that has already spent about 5 billion years on the main sequence. Scientist believe our Sun is roughly halfway through it's life. Source: The British Astronomical Association Stars are the source of light for all objects in outer space Earth’s Moon Phases of the Moon (Textbook reference 12-3) waxing = increasing waning = decreasing gibbous = > ½ crescent = < ½ 47 Lunar Phases • New Moon • Waxing Crescent • First Quarter • Waxing Gibbous • Full Moon New Waxing FirstFull Quarter Gibbous Waxing Crescent 48 Lunar Phases • Full Moon • Waning Gibbous • Last Quarter • Waning Crescent • New Moon Waning Last Full Quarter Gibbous Crescent New 49 Rotate vs. Revolve • Rotation – spin of an object on its axis • Revolution – orbit of an object around another object 50 Why does one side of the moon always face us? • Moon rotates once every 27.3 days • Moon revolves once every 29.5 days • Moon’s rotation approximately equal to its revolution 51 Moon’s Orbit and Phases 52 Eclipses, 12.3 1. Lunar Eclipse 2. Solar Eclipse 3. Total Eclipse 53 54 55 A total eclipse of the sun occurs during the day! Only the corona is visible. 56 Tides •Effect of gravity between the moon and the sun 57 Spring Tides • When the sun, the moon, and the Earth are all o aligned in a 180 angle 58 Neap Tide • When the sun, the moon, and the Earth form a 90° angle 59 Stars are the source of light for all objects in outer space • Complete the standards-based reading handed out in class to address this concept • Answer the assessment questions that accompany the handout 60 SOLAR SYSTEM • The Sun • Eight Planets and Pluto • Sixty-one satellites of the planets • Many Comets and asteroids Formation of the Solar System (Textbook reference 15-5) A collapsing interstellar cloud • Stars and planets form from interstellar clouds – They appear dark because of dust blocking out the light – The light can cause it to glow, or even become heated – Stars and solar systems are “born” this way • Collapse accelerates – The collapse of this cloud is slow, but it accelerates and becomes denser at the center – This collapse and spin results in a flattening at the equatorial plane • Matter condenses – Our solar system may have formed this way when temperature and pressure caused hydrogen to fuse into helium – The temperature differential allowed for different elements to concentrate in different areas around the sun • This is why the inner planets are rocky and have a higher melting point • Outer ones are less dense and made of ice and gas Planetesimals • The planetesimals combined to get larger and in many cases to become the known planets. • Gas giants form – Jupiter was the first to form • Icy planetesimals combined to form it • Its mass (gravity) caused it to collect much of the debris – The others formed the same way, but Jupiter took most of the extraneous material • Terrestrial planets form – the merging of planetesimals in the inner portion of the disk – Made of materials that resist vaporization – Most of the gaseous material and “smaller stuff” consumed by the sun, hence fewer satellites. • Debris – – – – All of the “junk” left over Some became comets Some ejected from solar system or destroyed in collisions The asteroid belt between mars and Jupiter is the rest Planets…Wandering Stars? The Greeks called the five points of light that seemed to move among the stars ______, meaning “______”. • planets • wanderers The ancient Romans later called these planets: • • • • • Mercury Venus Mars Jupiter Saturn Greek Ideas: Earth at the Center (Textbook reference 14-1) Initially the geocentric theory stated that everything moved around the earth. Retrograde motion (apparent westward movement) led astronomers to find a different explanation Describe the ancient Greek beliefs of the solar system. • The ancient Greeks thought Earth was a stationary object and the sun, moon, and planets were on a rotating celestial sphere Checkpoint: What is a geocentric system? • A geocentric system is one in which Earth is at the center of a system of revolving planets. Figure 2: Interpreting Diagrams Where is Earth located in this illustration? • The Earth is in the middle of the solar system • The sun, moon, and a planet are orbiting Earth on a large circle, while moving on a smaller cirlce How is Ptolemy’s model of the solar system differ from the Greeks before him? • The Greeks before Ptolemy thought the universe was unchanging and the sun, moon, and planets moved together on a celestial sphere (like a carousel). Earth was stationary • Ptolemy introduced the idea of the sun, moon and planets rotating on little circles which rotate on bigger circles Copernicus’s Idea: Sun at the Center The heliocentric model (Copernicus) put the sun at the center and planets in orbit around it. Proximity to the sun caused planets to move at different speeds This explained retrograde Heliocentric • A description of the solar system which all planets revolve around the sun Guide For Reading: How do the heliocentric and geocentric descriptions of the solar system differ? • In a geocentric system, Earth is at the center of the revolving planets. • In a heliocentric system, Earth and the other planets revolve around the sun. What two discoveries made by Galileo supported the heliocentric description of the solar system? • Jupiter’s four moons revolve around the planet. • Venus goes through phases similar to those of Earth’s moon. Brahe and Kepler Brahe, a ______ ______, made much more accurate observations by carefully observing the positions of the planets for almost _____ years. • Danish astronomer • 20 What did Kepler discover about the orbits of the planets? • Kepler had discovered that the orbit of each planet is an ellipse. • Ellipse: an elongated circle or oval shape. The Space Program (textbook reference 13-2) • Space Race began in 1957 with the launch of the Soviet satellite Sputnik I – Satellite – an object revolving around another object • Humans in Space – Soviets launched the first human in 1961 • The Moon Landing – 1969, Apollo 11, and Neil Armstrong and Buzz Aldrin 80 Exploring the Solar System (textbook reference 14-1 continued) Ellipse • An elongated circle, or oval shape; the shape of the planets’ orbit • Kepler’s Laws – 1st law in general, the planets orbit the sun in an ellipse The eccentricity of the orbit is how “squashed” the orbit is – 2nd law a line drawn from the sun to any planet, sweeps out equal areas in equal times (although the orbital distance may be different) – 3rd law he defined the size of the ellipse and the orbital period (year) Which planet’s orbit did Kepler calculate to discover that a planet’s orbit is not a circle? • Mars Inertia and Gravity (textbook reference 12-2) 86 Inertia • Inertia: tendency of a moving object to continue in a straight line or a stationary object to remain in place. The more _____ an object has, the more ______ it has. • mass • inertia Gravity • Gravity: The attractive force between two objects; its magnitude depends on their masses and the distance between them. The strength of gravity depends on the ______ of the objects and the ______ between them. • mass • distance Figure 5: Interpreting Diagrams -What would happen if a planet had no inertia? • The planet would be pulled into the sun Figure 5: Interpreting Diagrams -What would happen if a planet had no gravity? • The planet would continue to travel straight off into space Guide For Reading: What two factors keep the planets in their orbits? • Newton concluded that two factors – inertia and gravity – combine to keep the planets in orbit. • Inertia keeps the planets the moving • Gravity from the sun keeps the planets from traveling off in space Reviewing Gravity • Gravity is the attractive force between 2 objects – It is affected by mass and distance • Gravity is what determines the orbit planets follow Dark Matter helps Gravitational Pull • Newton’s explanation of gravity supported Kepler’s laws of planetary motion. Solar System Characteristics (Textbook reference 14-3) • Inner Planets –Mercury, Venus, Earth, Mars • Terrestrial planets with atmosphere and crust 95 The Inner Planets • • • • 96 Terrestrial Planets 4 inner planets Similar densities to Earth Solid rocky surfaces Mercury • closest to the sun • 1/3 Earth’s size(or the size of Earth’s moon) • no moons • solid and covered with craters • almost no atmosphere • the eighth largest planet(second smallest planet) • Surface – covered with craters and plains – the plains formed much like the maria on the moon – the craters are smaller with less ejecta • Interior – the density suggests a dense core similar to the Earth – the magnetic field suggests its partially molten 98 Venus • • Sixth largest planet • Sister planet to Earth • About three-fourths the size of Earth • • Has no moons or rings • The brightest object in our sky besides the sun and moon because of proximity • and albedo 75% Surface is rocky and very hot (covered in craters, volcanoes and mountains) Atmosphere completely hides the surface and traps the heat. Probes and satellites have provided radar images of 98% of the 99 surface Earth • Third planet from the sun • Fifth largest planet • Liquid covers 71 percent of the Earth’s surface. • The Earth has one moon. • Only planet known to have life and liquid water • Atmosphere composed of composed of Nitrogen (78%), Oxygen (21%), and other gases (1%). Earth, from 6,100,000,000 km (3,700,000,000 miles) away – can you find it? Mars Fourth planet from the sun A thin atmosphere that contains mostly carbon dioxide Appears as bright reddish color in the night sky Surface features volcanoes and huge dust storms Has 2 moons: Phobos and Deimos Moons of Mars Phobos Deimos Solar System Characteristics (Textbook reference 25-4) • Outer Planets –Jupiter, Saturn, Uranus, Neptune, Pluto • Jovian planets have ring systems and gas atmospheres (J, S, U, N) 105 • Pluto is neither terrestrial or Jovian The Outer Planets (Textbook reference 14-4) • The Gas Giants • These planets include: Jupiter, Saturn, Uranus and Neptune • All larger than Earth by 15-300 times 106 Jupiter • The largest planet (1/10 of the sun and 11X Earth’s) • Better than 70% of the planetary mass of the solar system • 52% albedo • Has a banded appearance 107 Jupiter • Rings have 3 parts: Halo Ring, Main Ring, Gossamer Ring • Brightest planet in sky • Strong magnetic field • 60+ moons, 5 visible from Earth Density is relatively low for its size The is because of it composition (H and He in gas or liquid form. Rotation Shortest day in the solar system about 10hrs This fast spin distorts the shape This also contributes to its banded appearance Belts are low lying dark-colored clouds Zones are high light-colored clouds Moons More than 60, but some are very small Mostly composed of ice and rock Gravity assist 109 Jupiter’s Red Spot • “the great spot” is a storm of swirling gas that has lasted for better than 300 years • Jupiter does not have a solid surface. The planet is a ball of liquid surrounded by gas. Moons of Jupiter Jupiter has four large Galilean moons, twelve smaller named moons and twentythree more recently discovered but not named moons. We’ll take a look at the four large Galilean moons which were first observed by Galileo in 1610. Io – Io is the fifth moon of Jupiter. It’s the third largest of Jupiter’s moons. – Io has hundreds of volcanic calderas. Some of the volcanoes are active. Europa • Europa is the sixth of Jupiter’s moons and is the fourth largest. • It is slightly smaller than the Earth’s moon. • The surface strongly resembles images of sea ice on Earth. There may be a liquid water sea under the crust. • Europa is one of the five known moons in the solar system to have an atmosphere. Ganymede • Ganymede is the seventh and largest of Jupiter’s known satellites. • Ganymede has extensive cratering and an icy crust. Callisto • Callisto is the eighth of Jupiter’s known satellites and the second largest. • Callisto has the oldest, most cratered surface of any body yet observed in the solar system. Saturn • • • • • • Second largest planet Sixth from the sun. Slightly smaller than Jupiter Easily visible in the night sky Voyager explored Saturn and its rings. Made of materials that are lighter than water. (If you could fit Saturn in a lake, it would float!) Rings of Saturn • • • • 7 major rings made up of ringlets Gravity keeps the rings in place rings are not solid composed of small countless particles • rings are very thin. • Though they’re 250,000 km or more in diameter, they’re less than one kilometer thick • Moons • 55 moons • 31 moons – Largest moon, Titan, • Titan, the largest is bigger than Mercury • Odd among moons because of content with dense atmosphere and methane’s existence in 3 states 118 Uranus • • • • • 7th planet from sun Has a faint ring system (they are dark and hard to observe) 27 known moons Covered with clouds Uranus sits on its side with the north and south poles sticking out the sides. • 4x larger and 15Xmass of the Earth Uranus • Atmosphere Bluish appearance cause by methane gas Clouds are similar in appearance to the surface Liquid surface with a small solid core • Rotation Almost a top to bottom rotation Poles vacillate between 42 years of darkness and light 120 URANUS • Uranus has more moons (15) than any other planet except Jupiter (16) and Saturn (23)! 25 Mercury Earth Mars Jupiter Saturn Uranus Neptune Pluto 20 15 10 5 0 Number of Moons Norm Herr (sample file) Neptune • 4th largest planet • 8th planet from sun – Because of the orbits, from 1979 to 1999, Neptune was the ninth planet. • Discovered through math • 7 known moons • Great Dark Spot thought to be a hole, similar to the hole in the ozone layer on Earth • Like Uranus, the methane gives Neptune its color. • Atmosphere Neptune – Smaller and denser than Uranus but 4XEarth – Similar in color to Uranus (twins??) but does have some color variation on surface – Belts and zones give it texture • Moons and Rings – 13 moons Triton being the largest • Triton has retrograde orbit • Also has nitrogen geysers when heated by the sun • Rings are invisible from Earth but exist 123 The blue coloration of Neptune is probably due to the presence of methane Note the apparent storms 124 Pluto…a planet? • Today, Pluto is called a "dwarf planet.“ • A dwarf planet orbits the sun just like other planets, but it is smaller. • A dwarf planet is so small it cannot clear other objects out of its path. 125 Per NASA.gov. • In 2003, an astronomer saw a new object beyond Pluto. The astronomer thought he had found a new planet. The object he saw was larger than Pluto. He named the object Eris (EER-is). Finding Eris caused other astronomers to talk about what makes a planet a "planet." There is a group of astronomers that names objects in space. This group decided that Pluto was not really a planet because of its size and location in space. So Pluto and objects like it are now called dwarf planets. Pluto is also called a plutoid. A plutoid is a dwarf planet that is farther out in space than the planet Neptune. The three known plutoids are Pluto, Eris and Makemake (MAH-kee-MAH-kee). Astronomers use telescopes to discover new objects like plutoids. 126 Dwarf Planet Pluto • Pluto, is one of three plutoids. • It is a small (smaller than Earth’s moon), solid and icy • It is so far from the sun that it has never been visited by spacecraft. • It orbits the sun very slowly. Sample Quiz Questions Question: Which of the planets are rocky? Answer: The inner planets: Mercury, Venus, Earth and Mars Sample Question 2 • Which of the planets has the most satellites? Saturn! Image by Dave Dockery Astronomical Society of Las Cruces What Are Comets, Asteroids and Meteors? (textbook reference 14-5) Comet Ikeya Zhang Space Debris Comets A comet is basically a ball of ice and dust in space. The typical comet is less than 10 kilometers across. Most of their time Comet Hale Bopp is spent frozen solid in the outer Image by Harvard-Smithsonian Center for Astrophysics A comet orbits around the sun, in a wide, elliptical path. When a comet gets within a few million miles of the sun, it begins to melt, leaving a tail of gas and dust that is blown by solar winds Source: NASA Comet Hale Bopp Image by Harvard-Smithsonian Center for Astrophysics Reviewing Comets • Small icy bodies • Travel past the Sun • Give off gas and dust as they pass by • Tail of gasses called a coma Asteroids • Asteroid – rocks orbiting in space • Asteroid belt – 100,000 asteroids located between Mars and Jupiter –separates inner and outer planets 139 Asteroids • Small bodies • Believed to be left over from the beginning of the solar system billions of years ago • Largest asteroids have been given names Meteoroids • Meteoroid – smallest asteroids or comets – Come from asteroids colliding in space – Come from a comet breaking up and creating a cloud of dust continuing to move through the solar system 141 Meteors • Meteor – meteoroid striking Earth’s atmosphere • Meteorite – meteor that hits Earth’s surface 142 Solar System Activities • • • • • Order the Planets Fun with Planets Constellations of the Northern Sky Planets Solar System Units of Time from Space • Year – 1 revolution of Earth • Day – 1 rotation of Earth • Month – 1 revolution and/or rotation of Moon 144 Measuring Distances • What is a Light Year? – A light year is the distance light travels in a year. Light moves at a velocity of about 300,000 kilometers (km) each second; how far would it move in a year? – About 10 trillion km (or about 6 trillion miles). • Why do we use light years? – Show me how far 5 centimeters is. – Now show me 50 centimeters. – Now tell me (without thinking about it, or calculating it in meters) how far 500 centemeters is. 2000? 20,000? – We need numbers that make sense to us in relationship to objects; we scale up and use meters and kilometers for large numbers. Measurements in Space • Light year – distance light travels in one Earth year • Astronomical Unit – distance from Earth to Sun http://www.youtube.com/watch?v= 3bmb0YE9VGM 146 Are We Alone in the Universe? (textbook reference 14-6) • SETI Pseudoscience http://www.seti.org/seti-institute/about-seti/scientists vs http://www.chem1.com/acad/sci/pseudosci.html • “If it is just us, it seems like an awful waste of space.” – Ellie Arroway in Carl Sagan’s Contact 147