Introductions to Constellations

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Introductions to Constellations
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http//www.astro.umass.edu/ngow/
http//www.chinapage.com/astronomy/chart/celestial
chart.html
http//www.geocities.com/ResearchTriangle/System/8
870/memory/
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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

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Patterns of stars
Boundaries
http//www.astro.virginia.edu/class/oconnell/astr1
30/im/
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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

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The Northern Hemisphere
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About Constellations

• Stars in a constellation usually NOT physically
  associated with each others

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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

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What are the 88 Constellations?

• 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)

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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

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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

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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

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History of modern constellations

• Oldest systematic description of constellations
  Phaenomena, in 270 B.C. by Greek poet Aratus

http//www.wikipedia.org
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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

http//www.wikipedia.org
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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 todays astronomer, constellations refer not
  so much to the patterns of the stars, but to
  precisely defined areas of the sky

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• Modern constellations
• Greek Constellations
• Latin Names
• Many stars have Arabic names
• Al-Sufin, one of the greatest Arabic astronomers,
  translated Ptolemys book into Arab in the 10th
  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

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What are circumpolar Constellations?
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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
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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

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Circumpolar Constellations at Amherst
Cassiopeia
Ursa Major
Ursa Minor
Draco
Cepheus
Camelopardalis

• www.acmecompany.com/

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Questions

• Where on the earth can we see the maximum number
  of circumpolar constellations?
• - At the earths pole
• Where on the earth can we see the minimum number
  of circumpolar constellations?
• - At the earths equator

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Summary

• Definition of Constellation
• 88, patterns of stars, boundaries
• Asterisms
• Not official
• If theres 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

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Find the big dipper
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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.
  

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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!

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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

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• Summer Triangle
• ?? Altair, alpha Aquila
• ?? Vega, alpha Lyra
• ??? Deneb, alpha Cyg
• Winter Triangle
• Arcturus, the brightest star in the northern sky,
  in Bootes