Very simply, astrophotography (abbreviated AP) means taking pictures of space.  However, it is very different than daytime photography; different techniques must be used to get an acceptable image. 

A large percentage of celestial objects are extremely dim to the human eye – even under a dark sky.  In order to capture these faint targets, I use a long exposure in order to let the camera sensor collect more light.  When shooting with a DSLR, I use 60 second exposures, but several minute exposures are the norm in the AP community.

Unfortunately, one 60-second exposure of a target is not enough; you need a lot more than that to make a good image.  Random noise in the picture (caused by flawed electronics and cosmic rays), corrupts the image and makes it look ugly after processing.  To mitigate this, several pictures of a target are taken and averaged in software to create one “super-exposure”.  This effectively removes a large percentage of the noise.

However, even after averaging the images, the contrast is extremely low in the resulting image and faint details are invisible to the eye.  I still have to post-process it in image editing software.  I adjust the contrast and brighten up parts of the image to help the detail be seen.  Finally, the image is ready to be displayed!