• And - Andromeda the Princess of Ethiopia

    IAU Constellation
    And - Andromeda the Princess of Ethiopia

    Size

    19 of 88
    Astronomical Regions
    Northern

    Intro and Visual description

    Andromeda contains one corner of the Great Square of Pegasus (the star Alpheratz). Andromeda’s dress flows outward from the corner along three pairs of stars, with each pair slightly farther apart than the previous pair. Perhaps she is petting Pegasus, who bore the hero Perseus across the ocean on his mighty wings to save her from the sea monster Cetus.

  • Cas - Cassiopeia the Queen of Ethiopia

    IAU Constellation
    Cas - Cassiopeia the Queen of Ethiopia

    Size

    25 of 88
    Astronomical Regions
    Circumpolar (northern)
    Northern

    Intro and Visual description

    Trace an imaginary line from the Big Bear’s pointers on past Polaris. At an equal distance on the opposite side from the Big Dipper is Cassiopeia (KASS-ee-oh-PAY-uh), an ancient Queen of Ethiopia.

    As she sits on her W-shaped throne she circles round and round the pole. Like the Big Dipper, Cassiopeia is circumpolar and therefore visible no matter what the season or time of night. In the fall Cassiopeia is in the shape of a W and in the Spring she is in the shape of a M.

  • Peg - Pegasus the Flying Horse

    IAU Constellation
    Peg - Pegasus the Flying Horse

    Size

    7 of 88
    Astronomical Regions
    Northern

    Intro and Visual description

    Farther along on the line from the Pointers to Polaris and Cassiopeia is a large, nearly perfect square of four stars. This is the Great Square of Pegasus. Pegasus, the Winged Horse, lies almost directly overhead in autumn. Located east of Andromeda; signals the coming of Fall. Because Pegasus flies so fast, his hind quarters can’t be seen.

  • Per - Perseus the Hero

    IAU Constellation
    Per - Perseus the Hero

    Size

    24 of 88
    Astronomical Regions
    Northern

    Intro and Visual description

    Resembles a backward lambda. Located in the Milky Way, between Andromeda/Cassiopeia and Auriga/Taurus.

    Look for the Perseid meteor shower on August 12.

  • Psc - Pisces the Fishes

    IAU Constellation
    Psc - Pisces the Fishes

    Size

    14 of 88
    Astronomical Regions
    Zodiac
    Northern
    Equatorial

    Intro and Visual description

    South of Pegasus and Andromeda, near Aquarius. Pisces represents two fish tied together by two cords:

    • The western fish, a pentagon of stars just south of Pegasus, is an asterism known as the circlet.
    • The other fish lies on the opposite side of Pegasus, just under Andromeda.

    The brightest star, alpha-Piscium, is known as El-Rischa or the "knot" because it ties the two cords together with the two fish on the opposite ends. Alpha-Piscium lies nestled up next to Mira, a bright variable star of the constellation Cetus the Whale.

  • M31 - Andromeda Galaxy

    Object image

    M31, Galaxy Evolution Explorer, JPL, NASA

    Object image source

    Galaxy Evolution Explorer, JPL, NASA, Wikipedia
    Permission
    Public domain

    On one side of Andromeda’s dress is a patch of light called M31 or the Andromeda galaxy. The great galaxy in Andromeda shines at mag. 3.5. This beautiful spiral galaxy is the most distant object visible to the naked eye, yet the closest major galaxy to the Milky Way, about 2,200,000 light years away.

    Nearby are two small satellight galaxies, M32 (Elliptical galaxy), mag. 8.2. The other is NGC 205 (Elliptical galaxy), mag. 9.4.

    All the stars that are visible to the naked eye lie within our own Milky Way galaxy. This means that the stars that make up all the constellations, including Virgo and Leo and Coma Berenices, are stars of our own galaxy. The galaxies we see in these constellations are not actually located in the constellations, they are only viewed along the same line of sight. Were we to actually go to another galaxy, even the Andromeda galaxy (which is the closest major galaxy to the Milky Way, only 2.2 million light years away), then the stars of the Milky Way would not be distinguishable. It makes no sense to talk of the constellations of Andromeda or Virgo as seen from another galaxy, since from another galaxy any observer would see all of the Milky Way stars together, just as we see a small patch of fuzzy light when we look at the Andromeda galaxy. It is not that Andromedans would see our constellation Andromeda differently; they would not distinguish it from the Milky Way at all.

    The Andromeda galaxy has been known from early times. Al-Sufi described it as a "little cloud" in 964 AD. Simon Marius observed it in 1612 through a telescope, and described it as like a flame of a candle. It was not easy for astronomers to understand what a galaxy looks like. Early viewers of the Andromeda galaxy did not imagine that it was a star system like our own. Christian Huygens (HOY-gens) thought it was a hole in the heavens through which we might peer into the luminous regions beyond. Edmond Halley agreed, suggesting that the light came from a region of perpetual day, a shining ether filled with the light that originated on the first day of creation, before the formation of the Sun, Moon and stars. In 1845 Lord Rosse, using his great reflecting telescope, first resolved it into stars. In the 1920s Edwin Hubble--using the 100-inch telescope at Mount Wilson--used Cepheid variable stars to show that the Andromeda galaxy lay beyond the Milky Way. Thus Hubble established that the "nebulae" or cloudy spots which could be resolved into stars are actually external galaxies.