9/26/2016 Introductions to Constellations

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9/26/2016 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

9/26/2016 Patterns of stars Boundaries

9/26/2016 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

9/26/2016 The Northern Hemisphere

9/26/2016 About Constellations Stars in a constellation usually NOT physically associated with each others

9/26/2016 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

9/26/2016 What are the 88 Constellations? o14 men and women o9 birds o19 land animals o2 insects o10 water creatures o2 centaurs o1 head of hair o1 serpent o1 dragon o1 flying horse o1 river o29 inanimate objects, include scientific instruments (Microscopium, Telescopium)

9/26/2016 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

9/26/2016 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

9/26/2016 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

9/26/2016 History of modern constellations Oldest systematic description of constellations: Phaenomena, in 270 B.C. by Greek poet Aratus

9/26/2016 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 16 th century

9/26/2016 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

9/26/2016 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 10 th century Different cultures grouped stars and named constellation differently

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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

9/26/2016 What are circumpolar Constellations?

9/26/2016 Star Trail Anglo Australian Observatory 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

9/26/2016 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) –Ursa Major – Larger Bear –Ursa Minor – Smaller bear –Cassiopeia – Queen –Cepheus – King –Draco – Dragon –Camelopardalis – The Giraffe

9/26/2016 Circumpolar Constellations at Amherst Ursa MajorUrsa Minor Cassiopeia Cepheus Draco Camelopardalis

9/26/2016 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

9/26/2016 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

9/26/2016 Find the big dipper

9/26/2016 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.

9/26/2016 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!

9/26/2016 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