The Autumn Night Sky

As we move into autumn, the time changes, and it starts to get dark earlier. It is a great time to go stargazing. Here are a few notes taken from two earlier FAS Astronomers Blogs on what to look for in October, November, and December.

The Night Sky

During the Fall, find the Great Square of Pegasus to the south. Add a few more stars to find Pegasus itself, the upside-down flying horse, high in the sky. Off to the east of Pegasus is the constellation of Andromeda. If you wait to a little later in the evening, the constellation Perseus will be visible even more toward the east. It looks something like an upside down Y or maybe the wishbone from your Thanksgiving turkey.

Turn around and find the queen Cassiopeia to the north looking like a big W or M. Nearby is the faint King Cepheus resembling a child’s drawing of a house. Low in the horizon is the Big Dipper. Follow the two stars at the end of the bowl to find Polaris (the North Star) at the end of the tail of the Little Dipper. Notice that the Little Dipper is always found curved in toward the Big Dipper.

See our introduction to The Night Sky and a few suggested smart phone and tablet apps along with links to various star maps including Stellarium Web. The Astronomical League has monthly sky charts. You might also visit the new Kaleideum Digital Dome Planetarium for their sky tours (general museum admission rates apply).

The Deep Sky (Pegasus and Andromeda)

To the right and just above the nose of Pegasus (Enif) is the globular cluster [M15]. Draw a line from the intersection of the neck and head of Pegasus (Baham/Theta Pegasi) to Enif and extend it out just under ½ the distance to the cluster.

The wide, but diffuse, Andromeda Galaxy [M31] is found in Andromeda. It will appear as a fuzzy patch of light, but through a telescope from a dark sky location you might see the brighter central portion of the galaxy. To find it:

  1. Start with the star in the upper left corner of the Great Square of Pegasus – as it appears when looking south (Alpheratz).
  2. Hop one-two left across the bottom row of the Andromeda constellation through Delta Andromedae to the star Mirach.
  3. Then hop up one-two through Mu Andromedae to find the galaxy.

Below Mirach, around the same distance as to Andromeda, but in the opposite direction is the Triangulum Galaxy [M33]. It is technically in the constellation Triangulum – hence its name. Although a relatively wide galaxy, it is somewhat diffuse, so it might be difficult to see.

Several other galaxies (not shown in the diagram) can be found in and around Pegasus.

  • Stephan’s Quintet [NGC 7317 – NGC 7320] are five galaxies off the lower front leg of Pegasus.
  • The Deer Lick Group ([NGC 7331/C30] is found below Pegasus’ front legs.
  • The Propeller / Superman Galaxy [NGC 7479/C44] is a distant face-on spiral toward the front of Pegasus.
  • The Little Sombrero Galaxy [NGC 7814/C43] is a distant galaxy toward the rear of Pegasus.

The Deep Sky (Adjacent to Pegasus and Andromeda)

Aquarius, situated below the head of Pegasus, is the home to two deep-sky objects.

  • A favorite object is the Helix Nebula [NGC 7293 / C63], also known as The “Eye of God”, near the feet of Aquarius and above the star Fomalhaut in Piscis Austrinus. Draw a line from the junction of the neck and head of Pegasus through the four stars that make up the “squiggly” shape in Aquarius down 3/4 of the way toward Fomalhaut (while keeping a little to the right).
  • For more of a challenge, try to locate the globular cluster [M2] in Aquarius below the head of Pegasus.
    • Draw a line from the lower right corner of the Pegasus great square (Markab/Alpha Pegasi) through the intersection of the neck and head of Pegasus (Baham/Theta Pegasi). Extend it around ¾ of the distance to the cluster.
    • You can also use the top of the constellation Aquarius, and the four stars that make up a “squiggly” shape. Draw a line from Eta Aquarii (the left star) through Sadalmelik/Alpha Aquarii (the right star) and extend it roughly the same distance to the cluster.

Below the body of Pegasus down toward Pisces are two galaxies.

  • The face-on spiral Phantom Galaxy [M74] is half way up from the bend in Pisces near the right end of Aries.
  • Well below the Circlet of Pisces on the boarder between Sculptor and Cetus is the Sculptor Galaxy [NGC 253 / C65].

At the end of Andromeda, and off toward Perseus, are two additional deep-sky objects. Look for these after viewing Cepheus and Cassiopeia.

  • At the end of Andromeda’s upper row of stars, and on a line toward the double cluster in Perseus, is the Little Dumbbell Nebula [M76].
  • At the end of Andromeda’s lower row of stars (Almach), and on a line toward Perseus, is the Silver Silver (Outer Limits) Galaxy [NGC 891].

The Deep Sky (Cassiopeia, Cepheus, and Perseus)

One of the more interesting open clusters, and another Caldwell object, is the ET/Owl Cluster [C13, NGC 457] found near Cassiopeia. You can see two bright stars for its eyes, two stars for its feet, a row of stars representing its body, and several stars off in either direction for its arms. Many think it looks like an extra-terrestrial (ET) or an owl.

  • It can be found by drawing a line from the left of Cassiopeia’s W or right of Cassiopeia’s M (Segin) to Ruchbah and extending it half that distance. The cluster is just off the line toward Andromeda and Perseus.
  • You can also draw a line from the center star of the W or M (Navi) that intersects with the above line to create a right angle near the cluster.

A few other objects are found around Cepheus and Cassiopeia.

  • Up toward Cygnus from Cepheus is the Fireworks Galaxy [C12 / NGC 6946].
  • On the side of the Cepheus base toward Draco is the Iris Nebula [C4 / NGC 7023].
  • Under the base of Cepheus near the Garnet star is the Elephant Truck Nebula [IC 1396].
  • On the side of the Cepheus base toward Cassiopeia is the Wizard Nebula [NGC 7380] and the Cave Nebula [C9 / SH 2-155].
  • Situated between the Cepheus base and a bit more toward Cassiopeia are the Lobster Claw Nebula [SH 2-157], the Bubble Nebula [C11 / NGC 7635], and the Scorpion Cluster [M52].
  • On the side of the Cepheus roof toward Cassiopeia is the Teddy Bear Nebula [NGC 7822].
  • Above the left side of Cassiopeia’s M near the star Shedar is the Pacman Nebula [NGC 281].
  • At the center of Cassiopeia near the star Navi is the Ghost of Cassiopeia [IC 63].

The Perseus Double Cluster [C14, NGC 869 and NGC 884] is a Caldwell object worth looking for between Perseus and Cassiopeia.

  • Draw a line from the left base of the triangle at the top of Perseus (Al Fakhbir/Gamma Persei) through the two stars marking the left middle of Cassiopeia’s W or right middle of Cassiopeia’s M (Ruchbah and Navi). The Double Cluster is halfway between Al Fakhbir and Ruchbah.
  • Or draw a line from Navi and Ruchbah through the intersection of the Perseus upside-down Y and brightest star in Perseus (Mirfak). The Double Cluster is around 1/3 of the way from Ruchbah to Mirfak.

In the same general area of the Double Cluster are the wide Heart Nebula [IC 1805] and Soul Nebula [IC 1848]. Hanging off the lower part of the Heart Nebula is the Fish Head Nebula [IC 1795].

Two other open clusters are found around Perseus.

  • The Perseus Open Cluster [M34] is located just a bit toward Perseus from the middle of the line between the lower right end of the Perseus upside down Y (Algol) and the end of the lower row of Andromeda (Almach).
  • The Alpha Persei Cluster [Mel 20] is a wide cluster surrounding the star Mirfak.

Following Cassiopeia, along a line from the star Segin, is the Hidden Galaxy [C5 / IC 342] in Camelopardalis.

A Few References

Posted

by

Bruce Gavett

on

in

Tags:

, , , ,