Summertime Constellations Part 1: Ursa Major

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Summertime ConstellationsPart 1 Ursa Major

• Name
• Prominent Stars
• Mythology
• Directions
• Deep Space Objects
• By Richard Fisher

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Ursa MajorQuestions

• Ursa Major is the first constellation of the
  night time sky. It means the Big Bear. Ursa
  Major is often called another name, the Big
  Dipper. This is because the seven brightest
  stars in the constellation look like a ladle or a
  dipper.

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The Stars of Ursa MajorQuestions

• The seven prominent stars of Ursa Major are
  Dubhe (Arabic for bear), Merak (Arabic for the
  flank of the bear), Phecda (Arabic for thigh of
  the bear), Megrez (Arabic for the root of the
  tail), Alioth (meaning bull), Mizar (which means
  the groin of the bear), and Alkaid (Arabic for
  chief of the mourners). Of these Mizar is the
  most interesting. It is a visual binary. If you
  look very closely you will notice another star
  very close to Mizar. They are called visual
  binaries. This means the two stars only appear
  to be together. They are in actuality very far
  apart. Through a telescope you can see that
  Mizar actually does consist of two stars.
  Therefore, Mizar is both a visual binary and a
  true binary star.

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Mythology of Ursa Major

• There are many possible origins for this
  constellation. To the ancient Greeks Ursa Major
  was the bear. According to some Greek legends,
  Callisto, a maiden desired by Zeus, was turned
  into a bear by Hera, Zeuss jealous wife. Zeus
  placed the unfortunate bear in the sky along with
  her son Arcas, who became the Little Bear, Ursa
  Minor. Zeus had to pull on each of the bears
  tails to get them into the sky. For this reason
  their tails are longer than a normal bear. Hera
  applied to the powers of the ocean to avenge this
  offense to her honor and authority, and so the
  bears were forced continually to circle the North
  Star, never allowed to set and rest beneath the
  ocean.

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Directions to Ursa Major

• Ursa Major is always near the Celestial North
  Pole. During the month of July at around 10 PM
  it is slightly West of North. Turn your body so
  that you are facing North. If you are not sure
  of the direction of North either use a compass or
  remember where the sun set earlier in the
  evening. In the case of the latter, North will
  be a 90 degree turn to the right. Look up into
  the sky at a 45 degree angle. You will see seven
  bright stars that form the shape of a milk ladle.
  This is the Big Dipper the most recognizable
  portion of Ursa Major. These seven stars form
  the rear body of the bear and its tail. Use
  these stars and the star diagram on an earlier
  page to find the bears head and legs.

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Deep Space Objects in Ursa Major

• There are several deep space objects in Ursa
  Major. Many of them are galaxies. The more
  easily seen ones are shown above. There is even
  a star in Ursa Major that has planets. In the
  next few pages you will see some of these images.

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M-101Questions

• M-101 is a large face-on spiral galaxy with low
  surface brightness. It is about 7' in diameter.
  It has a brighter core of stars surrounded by an
  envelope which sometimes can be seen as spiral
  arms.

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M-108

• M-108 This galaxy has an evident central bulge, a
  stellar nucleus, and tapering ends. The western
  end appears to be tapered more than the eastern
  end, and dark markings are seen along its
  northern edge.

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M-109

• M-109 is 8'x4. It has a faint stellar nucleus
  with spiral arms that can be seen leading to the
  north and south.

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M-81

• M-81 This is a large and beautiful spiral galaxy,
  that is 10' long and 4' wide. It has a bright
  core with a stellar nucleus, and spiral arms can
  be seen, especially with averted vision.

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M-97Questions

• M-97 The Owl Nebula. This large planetary nebula
  is almost 3' in diameter, and appears as a gray
  puff of light, slightly brighter in the center.
  At times, especially with averted vision, the
  'eyes' of the owl can be seen as two slightly
  darker spots.

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A Star with PlanetsQuestions

• The circle shows the location of the class G1
  star (the sun is a G2 star) 47 Ursae Majoris. It
  has at least two planets. The innermost planet
  is 196 million miles from the star and the second
  is 348 million miles from the star. The planets
  are near the size of Jupiter and Saturn. The
  inner planet orbits the star once every 2.98
  years. The outer planet has a period of 7.1
  years.