Honors Space Science Unit(Textbook reference Chapters 12, 24, 25 and 26)
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
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 • by George Greaney
Astronomy is a science that attempts to understand the make-up and the history of the universe. What is astronomy? Galaxy M83 in Hydra by George Greaney
Stars • Nebula • Planets • The Sun • Star clusters • Galaxies • Galaxy clusters • Dark matter • Black holes • The Great Andromeda Galaxy • by George Greaney
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. Astronomer Serena Kim at work At Cerro Tololo in Chili Source: Applied Theoretical and Computational Physics DivisionLos Alamos National Laboratory
What is an amateur astronomer? Amateurs and their tools
What is an amateurastronomer? 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 26-5 Hubble’s Law How Did We Get Here? The Big Bang Theory Steady-State Theory Plasma Theory Continued Expansion
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”?(Textbook reference 26-4) • 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 We can see • stars • star clusters • nebulae • galaxies How do we know what our galaxy looks like?
Reviewing Galaxies • Groups of stars, planets, and space debris • Irregular, Elliptical, Spiral • Milky Way is our galaxy
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 26-2 and 26-3) • 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
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 DockeryAstronomical Society of Las Cruces Source: The British Astronomical Association
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
Hertzsprung-Russell Diagram Video on the Hertzsprung-Russell Diagram The Doppler Effect: Red Shift – stars moving away from Earth Blue Shift – stars moving toward Earth Spectroscopy Video
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 (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 26-1, 24-2 and 24-3) • 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
The Sun: Seasons 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
What causes the seasons? • 23.5° tilt of Earth’s axis • Direct vs. indirect sun rays • Length of daylight
Fall Summer Sun Winter Spring
The Sun: Solar Energy 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
The Sun: Winds Winds: Caused by differences in air pressure Larger differences in pressure=stronger winds Local Winds: Where land meets large bodies of water Sea Breeze Land Breeze Global Winds: Trade winds Westerlies Polar easterlies
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
Earth’s Moon Stars are the source of light for all objects in outer space
Phases of the Moon (Textbook reference 25-2) waxing = increasing waning = decreasing gibbous = > ½ crescent = < ½
New Waxing Crescent Full First Quarter Waxing Gibbous Lunar Phases • New Moon • Waxing Crescent • First Quarter • Waxing Gibbous • Full Moon
Full Waning Gibbous Last Quarter Waning Crescent New Lunar Phases • Full Moon • Waning Gibbous • Last Quarter • Waning Crescent • New Moon
Rotate vs. Revolve • Rotation – spin of an object on its axis • Revolution – orbit of an object around another object