lec1 - Astronomy • S tu d y o f th e U n i v e r s e •...

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Unformatted text preview: Astronomy • S tu d y o f th e U n i v e r s e • T h e o l d e s t s c i e n c e , a n d s ti l l o n e o f th e m o s t a c ti v e s c i e n c e s • W h y i s A s tr o n o m y a S c i e n c e ? • T h e S c i e n ti fi c M e th o d • O b s e r v a ti o n s v s . T h e o r y Astronomers study primarily the “light of distant objects”. A Few Examples of the Tools Used: Ground-based Observatories, e.g., at Mauna Kea, Hawaii Hubble Space Telescope Spitzer Space Telescope The Earth: Our Home T h e S u n : O u r E n e rg y S o u rc e About 109 times as large as the Earth in radius. (Over 1 million Earths would fit inside the Sun’s volume.) Earth orbits the Sun at an average distance of 150 million kilometers= 1 AU. It would take 11,780 Earths lined up side to side to bridge the 1 AU between Earth and Sun. T h e M o o n : T h e E a r th ’ s o n l y N a tu r a l S a te l l i te About 384,000 km (0.0025 AU) away. About ¼ of the Earth in size About 1/100 of the Earth in mass Mars: The Little Red Planet View from Here (actually from HST) View from Pathfinder Spacecraft Jupiter: The “Ruling Gas Giant” Saturn: Another Giant Planet Comets/Meteors/Asteroids: Solar System Debris Comet Hale-Bopp from Val Parola Pass, Italy (blue ion tail and white dust tail) Potato-shaped Asteroid Ida (36 miles long) and its tiny moon Dactyl (1 mile across)! (picture from Galileo spacecraft) The Solar System Boundary between Solar Wind and interstellar space at 100 AU from the Sun The Nearby Stars Proxima Centauri: The Nearest Star (4.2 light years away) Polaris: The North Star (390 ly away) P l e i a d e s S ta r C l u s te r ( “ T h e S e v e n S i s te r s ” ) “Open Cluster” About 400 ly away About 13 ly across About 3000 stars T h e L a r g e s t “ B a l l o f S ta r s ” i n o u r G a l a x y Omega Centauri globular cluster 15,000 ly away 150 ly across 10 million stars! Stellar Births The Orion Nebula About 1500 ly away Stars forming in interstellar gas/dust clouds Stellar Deaths Crab Supernova Remnant Explosion observed on Earth in 1054 AD The Milky Way: Our Home Galaxy You Are Here The Solar System is located at the edge of a spiral arm, 30,000 light-years from the center of the Milky Way Galaxy! It takes us 250 Million years to complete one orbit around the Galaxy’s center! O u r N e ig h b o rin g G a la x ie s The Large Magellanic Cloud galaxy A satellite galaxy to the Milky Way 180,000 ly away Andromeda Galaxy Nearest major galaxy. 2 million ly away. T h e L o c a l G ro u p o f G a la x ie s Contains 3 large spiral galaxies--Milky Way, Andromeda (M31), and Triangulum (M33)—plus a few dozen dwarf galaxies with elliptical or irregular shapes. Gravitationally bound together—orbiting about a common center of mass About 6.5 million light-years in diameter The Local Supercluster A cluster of many groups and clusters of galaxies. Largest cluster is the Virgo cluster containing over a thousand galaxies. Clusters and groups of galaxies are gravitationally bound together into Superclusters. The Local Supercluster is about 130 Million light-years across. “Looking out” as far as we can: 1.3 Billion lightyears Surveys of galaxies reveal a web-like or honeycomb structure to the Universe. Great walls and filaments of matter surrounding voids containing no galaxies. Probably 100 Billion galaxies in the Universe. T h e U n iv e rs e • T h e O b s e rv a b le U n iv e rs e is a b o u t 2 7 b i l l i o n l i g h t y e a r s a c r o s s ( a b o u t 1 3 .5 b i l l i o n y e a r s o l d .) • H o w d i d i t s ta r t? • W h a t w i l l i ts fu tu r e b e ? • W h a t i s d a r k m a tte r ? • W h a t is d a rk e n e rg y ? Review of Basic Math • • • • • P o w e r s o f 1 0 : S c ie n tif ic N o ta tio n L o g a r ith m s S im p le A lg e b r a S im p le G e o m e tr y I n te r p r e tin g G r a p h s • R e v ie w U n it 1 f r o m L a b M a n u a l ...
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