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About the image:
There are several named nebulae within this image. In the centre of the image is The North American Nebula, which is an emission nebula. It can be found fairly close to the star Deneb (see star chart below). Towards the centre bottom of the image is a small nebulous cloud known as the Pelican Nebula. Within the North American Nebula is a prominent structure known as The Cygnus Wall, which I am currently shooting so check back soon for an update. This is the m shaped structure just slightly up and left from the centre of the image. The whole north american nebula is approximately 140 light years across. Because it is an emission nebula, it is literally glowing in space, with the gases being ionised by a very hot star, believed to be the star named J205551.3+435225, estimated to have a temperature of over 40,000 Kelvin - to put that in perspective, our own sun is only 5,778 Kelvin.
Object Brightness:
Most nebulae, with the exception of a handful, are so faint that they are not visible to the human eye, but just how faint are they? Due to the many hours of image capturing involved to bring this dim objects from out of the darkness into images like the one above, it doesn't really give you an idea of just how faint they are, and some are much fainter than others and require tens of hours of image capture to collect all the details. To signify an objects brightness, it is given a value that is referred to as the 'Apparent Magnitude', this is a logarithmic scale where each point on the scale is 2.5x brighter or fainter than the previous point. The chart below gives you an idea of how much fainter an object is the higher it's apparent magnitude - this scale goes all the way from -27 (The sun) to 32 (Visible light limit of Hubble Space Telescope)
Where in the sky is it?
The North american Nebula can be found in the constellations of Cygnus, check the sky map below (click to expand).
