November 2017

                              Tony Martinez

Each month I will describe sights of interest in the night skies of South Carolina. These sights will be broken down into four sections; what you can see with the naked eye, with binoculars, with a small refracting telescope and with a Dobsonian reflector. The best time to view the night sky is at and around the times when the Moon is not visible, what is known as a New Moon; which will occur this month on November 18th. For November, your best viewing nights will be from November 8th to the 23rd. The Star chart below is set for Florence, SC on November 15th at 9 pm. Note: A table of contents for earlier columns is located in the November 2016 column.

The Northern Cross (Cygnus the Swan):

The cooler weather is bringing clearer skies, so enjoy. You may notice that this is the only season that has no impressive constellations low in the southern sky. Remember, Winter – Orion, Spring – Leo, Summer – Scorpius and Sagittarius. You will also notice the absence of stars in the south. There is only one somewhat bright star in the south this month, Fomalhaut in the constellation Piscis Austrinus. Don’t feel bad, most amateurs have never heard of that constellation.

So this month I suggest you spend some time observing the prominent constellation Cygnus, high in the western sky. This constellation can be enjoyed with simple amateur equipment, but it also contains some objects that are challenging for the advanced amateur astronomer.

First, observe the naked eye view. Cygnus represents a swan in flight.  The brightest star in this constellation is Deneb, derived from the Arabic word for tail. We can also see the long neck of the swan ending at an interesting star, Albireo; and of course, we can see the extended wings. From its rising in the spring and through the summer, it looks like a swan in flight, and it is flying along the Milky Way. This time of year, it looks like it is diving/falling down from the sky, and as such, it now looks like the asterism, the Northern Cross. Specifically, it is in the shape of a perfect Christian cross. Many people ask me if there is a Southern Cross; the answer is yes; it is called the constellation Crux, and it is the smallest constellation in the sky.

I have searched it out on my many trips to Mexico, and it is not a very impressive cross asterism. On a clear dark night, you can see seven stars forming the Northern Cross, however, the Southern Cross is defined by only four stars, and a fifth star interferes with the cross asterism. However, in the southern hemisphere, it is highly regarded, and is found on the national flags of five countries.

Cygnus also contains my favorite star, Albireo (the bottom star of the cross or the head of the swan). Albireo is a double star. There are hundreds of double stars in the sky, but Albireo is special because of the colors. One star is sapphire blue, and the other is golden yellow.

The best way to see this colorful double star is through a simple telescope at low power, or through large binoculars; check it out.

There are only two Messier objects in Cygnus, M29 and M39, both are unimpressive open star clusters. There is an interesting Messier M27 (The Dumbbell) that many people assume is in Cygnus, but it is in a small constellation nearby called Vulpecula; see its location in the Cygnus image above. While visiting Cygnus, check it out. M27 is called a planetary nebula, which is the remnant of a dead star, see image below.

This object is faint and fuzzy, but you will see the dumbbell shape.  When viewing this object through large binoculars (25 X 100 mm) at a dark sky location, for some unknown reason, it gives a 3D optical illusion. It appears to be standing out in front of the background stars.

There are two challenging objects to locate in Cygnus; the North America nebula, and the Veil Nebula. As I discussed last month, having good dark sky viewing in our part of the country can be quite difficult. Whenever attempting to view most nebulae, a dark clear sky is essential. I have been in several dark sky sites, but I have yet to see the North America or Veil nebulae. This month the North America nebula is found just to the left of the star Deneb; see below.

The best way to view the North America nebula is at low power, with a large aperture. If you use a large Dobsonian telescope, you may have trouble attaining a low enough power. Your best chance is by viewing with both eyes. Therefore, large binoculars should work. I have tried and failed with 25 X 100 mm binoculars, but I believe it is possible if conditions are perfect. Our new 25 X 150 mm binoculars may supply the extra light gathering needed to see this elusive nebula. Below is an impressive image of the North America nebula.

Note in the North America nebula image, there is a second nebula to the right called the Pelican. If you do get to see the North America nebula, it is not likely that you will see the super dim Pelican. This image is from long exposure astrophotography.

I have been told that viewing the Veil nebula is next to impossible without the use of special nebula filters. The Veil nebula was formed from a super nova, and exists as two sections to the left of the star Gienah; see image above.

Enjoy your tour of Cygnus.

Naked Eye Sights: The Northern Cross (Cygnus the Swan)

Binocular Sights (7 to 10 power): M27 (The Dumbbell), try for the North America Nebula, M31 (the Andromeda Galaxy).

Telescope Sights (60-100mm): Albireo

Dobsonian telescope (6 -8 inch): Albireo, M27, the North America Nebula; at your lowest power using a wide field eyepiece.

See you next month!

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