Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Introductions to Constellations 4/29/2017 http://www.astro.umass.edu/~ngow/ http://www.chinapage.com/astronomy/chart/celestialchart.html http://www.geocities.com/ResearchTriangle/System/8870/memory/ 4/29/2017 What did the ancient people use stars (patterns of stars) for? • • • • Navigation – sailing, travel Seasons – when to plant and harvest Preserve myths, traditions, etc Group the brighter stars into patterns, - constellations 4/29/2017 Patterns of stars Boundaries http://www.astro.virginia.edu/class/oconnell/astr130/im/ 4/29/2017 Constellation • One of the 88 named Regions of sky defined by the International Astronomical Union (IAU) • Identified with the officially recognized Patterns of Stars that lie within the boundaries of the region 4/29/2017 The Northern Hemisphere 4/29/2017 About Constellations • Stars in a constellation usually NOT physically associated with each others 4/29/2017 About Constellations • Some constellations have a lot of bright stars (Orion), others mainly contain dim stars. • Symbolized figures, some patterns don't look like the subjects 4/29/2017 What are the 88 Constellations? o o o o o o o o o o o o 14 men and women 9 birds 19 land animals 2 insects 10 water creatures 2 centaurs 1 head of hair 1 serpent 1 dragon 1 flying horse 1 river 29 inanimate objects, include scientific instruments (Microscopium, Telescopium) 4/29/2017 Asterism • A generally recognized smaller/cuter pattern of stars that is not one of the officially recognized constellations • Whether or not a region of sky is named after it – yes: constellation; no: asterism 4/29/2017 Asterism • • • • • • The Big Dipper in Ursa Major The Little Dipper in Ursa Minor The “W” of Cassiopeia Lozenge of Draco House (Cepheus) Sword of Orion, Belt of Orion 4/29/2017 History of Modern Constellations • (Uncertain) Origin: Nomad in Mesopotamia named some northern constellations more than 5,000 years ago, including Leo and Taurus • More constellations were added by Babylonian, Egyptian and Greek 4/29/2017 History of modern constellations • Oldest systematic description of constellations: Phaenomena, in 270 B.C. by Greek poet Aratus http://www.wikipedia.org 4/29/2017 History of modern constellations • In 150 A.D., Ptolemy published The Almagest (The Great Book) – A catalog of 1022 stars, with estimates of their brightness, arrange into 48 constellations. The 48 constellations formed the basis for our modern constellations • 44 southern constellations were added after 16th century 4/29/2017 http://www.wikipedia.org History of modern constellations • IAU officially adopted the list of 88 constellations that we use today in 1922 • Definitive boundaries between constellations were set in 1930 – 88 regions cover the ENTIRE sky • For today’s astronomer, constellations refer not so much to the patterns of the stars, but to precisely defined areas of the sky 4/29/2017 • Modern constellations – Greek Constellations – Latin Names – Many stars have Arabic names • Al-Sufin, one of the greatest Arabic astronomers, translated Ptolemy’s book into Arab in the 10th century • Different cultures grouped stars and named constellation differently 4/29/2017 4/29/2017 Are constellations permanent? • Are stars fixed? • Stars all move relative to the Sun, with speed of many kilometers per seconds • Stars are far away, and stars in the constellations are at different distances • Stars will move, shapes of constellations will change, but it takes thousands of years to see the change 4/29/2017 What are circumpolar Constellations? 4/29/2017 Star Trail • Earth rotates about an axis that is pointed very close to the star Polaris • Stars rise in the east and set in the west everyday Anglo Australian Observatory 4/29/2017 Circumpolar Constellations • A Constellation that NEVER rises or sets as seen at a certain latitude • Six circumpolar constellations seen in Amherst (42º N, 72º W) – – – – – – 4/29/2017 Ursa Major – Larger Bear Ursa Minor – Smaller bear Cassiopeia – Queen Cepheus – King Draco – Dragon Camelopardalis – The Giraffe Circumpolar Constellations at Amherst Ursa Major Cepheus Cassiopeia Ursa Minor Draco Camelopardalis 4/29/2017 • www.acmecompany.com/ Questions • Where on the earth can we see the maximum number of circumpolar constellations? • - At the earth’s pole • Where on the earth can we see the minimum number of circumpolar constellations? • - At the earth’s equator 4/29/2017 Summary • Definition of Constellation – 88, patterns of stars, boundaries • Asterisms – Not official – If there’s a region of sky named after it • Stars in a Constellation usually do not have physically connections • Circumpolar constellations – Never rise or set – Remember the 6 circumpolar constellations seen at Amherst 4/29/2017 Find the big dipper 4/29/2017 How to find Polaris from the Big Dipper and Cassiopeia • From the Dipper, follow the two stars at the end of its bowl toward Cassiopeia. There, about five times the separation of these two stars, you'll find Polaris. • Use the middle three stars of Cassiopeia's "W" as an arrow to point in the direction of the Dipper. Halfway there you will encounter Polaris. 4/29/2017 Do we see different constellations at different seasons? • Earth rotates about an axis that is pointed very close to the star Polaris • Stars rise in the east and set in the west everyday • It takes 4 minutes less for a star to come back to the position yesterday • If we observe the sky at the same time every night, (say 9pm), the positions of constellations will change night by night • 4 minutes each day, is 24 hours for 365 days! • At different seasons, we see different constellations! 4/29/2017 Zodiac Constellations • Constellations of stars that lie along the apparent path of the Sun across the heavens (the ecliptic) • Aquarius, Pisces, Aries, Taurus, Gemini, Cancer, Leo, Virgo, Libra, Scorpio, Sagittarius, Capricorn 4/29/2017