The “North America” Nebula
Posted by Brian Ventrudo
Now to the faint, sprawling nebula NGC 7000 in the constellation Cygnus. This vast region of glowing gas presents an elusive but rewarding target for stargazers armed with simple optics and pristine sky. In optics and certainly in images, this nebula bears an astonishing resemblance to the continent of North America, so it’s often called the North America Nebula…
Like many glowing reddish-pink nebula, the North America Nebula is an HII region (pronounced “H-two”), a large cloud of hydrogen that’s ionized by hot stars embedded within the nebula. Astronomers once thought the star brilliant Deneb set this nebula aglow, but the very hot 6th-magnitude star HD 199579, one of the many stars buried within the nebula, is the culprit.
The North America Nebula is easy enough to find. It lies about 3º east of the star Deneb, the brightest in Cygnus, and 1º west of ξ (xi) Cygni (see map above). It’s large, spanning 2º of sky, but it’s not easy to see in anything but dark and clear sky. Binoculars will do nicely to view its full extent, and you can see parts of the nebula without optics at all. A wide-field and low-power telescope enhances the view somewhat, especially with a light-pollution filter to enhance the contrast. If you have such a filter and if you can’t see the nebula with your naked eye, hold the filter up to your eye to improve contrast. It may pop right out.
Once you see the nebula, look carefully for detail. Mexico and Florida are the faintest regions of the nebula, while Central America and Canada are the easiest to see. The coasts of the “continent” are also well defined. Look also for concentrations of stars around Washington State and the midwestern U.S. These are the open star clusters Collinder 428 and NGC 6997, respectively.
The North America Nebula appears grey to most observers and slightly green to others. Reds and pinks are visible only in photographs (see image below). The nebula, like most objects in Cygnus, lies in a rich and splendid region of the Milky Way. This is also a fairly easy region to photograph with a simple DSLR on a tripod (this free audio recording at Stargazer University will tell you how).
If you can see the North America Nebula, look for the Pelican Nebula about 1º off the “east coast” of NGC 7000. The Pelican, which is much harder to see, is part of the same HII complex and is separated from NGC 7000 by a dark lane of dust. The whole complex lies about 1800 light years away and spans some 50 light years.