          APOD: 2017 November 21 - Big Dipper over Pyramid Mountain

                         Astronomy Picture of the Day

    Discover the cosmos! [1] Each day a different image or photograph of our
 fascinating universe is featured, along with a brief explanation written by a
                           professional astronomer.

                               2017 November 21
                                      [2]
                      Big Dipper over Pyramid Mountain
                  Image Credit & Copyright: Steve Cullen [3]

Explanation: When did you first learn to identify this group of stars?
Although they are familiar to many people around the world, different cultures
have associated this asterism [4]  with different icons and folklore [5] .
Known in the USA [6]  as the Big Dipper [7] , the stars are part of a
constellation designated by the International Astronomical Union [8]  in 1922
as the Great Bear (Ursa Major [9] ). The recognized star names of these stars
are (left to right) Alkaid [10] , Mizar/Alcor [11] , Alioth [12] , Megrez [13]
, Phecda [14] , Merak [15] , and Dubhe [16] . Of course, stars in any given
constellation [17] are unlikely to be physically related [18] . But
surprisingly, most of the Big Dipper stars do seem to be headed in the same
direction as they plough [19]  through space, a property they share with other
stars spread out over an even larger area across the sky. Their measured
common motion [20]  suggests that they all belong to a loose, nearby star
cluster [21] , thought to be on average only about 75 light-years [22]  away
and up to 30 light-years across. The cluster is more properly known as the
Ursa Major Moving Group [23] . The featured image [24]  captured the iconic
stars recently above Pyramid Mountain [25] in Alberta [26] , Canada [27] .

          Free APOD Lectures: January 5 in NYC & January 9 in DC [28]
                      Tomorrow's picture: open space [29]

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Site notes:
  [1] archivepix.html
  [2] image/1711/BigDipperMt2_Cullen_1365.jpg
  [3] https://www.stevecullenmedia.com/about/
  [4] https://en.wikipedia.org/wiki/Asterism_(astronomy)
  [5] https://en.wikipedia.org/wiki/Big_Dipper#Names_and_places
  [6] https://en.wikipedia.org/wiki/United_States
  [7] ap130421.html
  [8] https://www.iau.org/administration/about/
  [9] https://en.wikipedia.org/wiki/Ursa_Major
  [10] https://en.wikipedia.org/wiki/Eta_Ursae_Majoris
  [11] https://en.wikipedia.org/wiki/Mizar_and_Alcor
  [12] https://en.wikipedia.org/wiki/Epsilon_Ursae_Majoris
  [13] https://en.wikipedia.org/wiki/Delta_Ursae_Majoris
  [14] https://en.wikipedia.org/wiki/Gamma_Ursae_Majoris
  [15] https://en.wikipedia.org/wiki/Beta_Ursae_Majoris
  [16] https://en.wikipedia.org/wiki/Alpha_Ursae_Majoris
  [17] http://www.astro.wisc.edu/~dolan/constellations/
extra/constellations.html
  [18] http://www.comfychair.org/~cmbell/myth/myth.html
  [19] http://www.dibonsmith.com/uma_con.htm
  [20] http://www.kencroswell.com/DescendantsOfTheDipper.html
  [21] ap051118.html
  [22]
https://www.grc.nasa.gov/www/k-12/Numbers/Math/Mathematical_Thinking/
how_long_is_a_light_year.htm
  [23] http://en.wikipedia.org/wiki/Ursa_Major_moving_group
  [24]
https://www.facebook.com/cullenmedia/photos/
a.1042986535821786.1073741827.1034682046652235/1446299962157106/?type=3&theater
  [25] https://en.wikipedia.org/wiki/Pyramid_Mountain_(Alberta)
  [26] https://en.wikipedia.org/wiki/Alberta
  [27] https://en.wikipedia.org/wiki/Canada
  [28] http://asterisk.apod.com/viewtopic.php?f=28&t=37750
  [29] ap171122.html
  [30] ap171120.html
  [31] archivepix.html
  [32] lib/apsubmit2015.html
  [33] lib/aptree.html
  [34] https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search
  [35] calendar/allyears.html
  [36] /apod.rss
  [37] lib/edlinks.html
  [38] lib/about_apod.html
  [39] http://asterisk.apod.com/discuss_apod.php?date=171121
  [40] ap171122.html
  [41] http://www.phy.mtu.edu/faculty/Nemiroff.html
  [42] http://www.phy.mtu.edu/
  [43] https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html
  [44] http://www.astro.umd.edu/
  [45] lib/about_apod.html#srapply
  [46] https://www.nasa.gov/about/highlights/HP_Privacy.html
  [47] https://astrophysics.gsfc.nasa.gov/
  [48] https://www.nasa.gov/
  [49] https://www.nasa.gov/centers/goddard/
  [50] http://www.mtu.edu/
