A star is a very hot and luminous object, so luminous that we can see some of them which are thousands of lightyears away with our naked eye. It is powered by nuclear fusion, a process that occurs in its core. For a large part of the star’s lifetime, around 90%, it is hydrogen burning that dominates. Protons (i.e. Hydrogen nuclei) are merged together to form Helium nuclei, releasing energy in the form of heat and electromagnetic radiation, which reaches us partly as visible light.

Historically, the word “nebulosity” or “nebula” was used to describe all Deep Sky object. As it was unknown that galaxies beyond the Milky Way existed, it was assumed that all the hazy objects seen through early telescopes must be similar. In the Deep Sky Classification Article, we’ve started to look at the different deep sky objects and the types of nebulae you will encounter as you practice astrophotography.

In the article Deep Sky Classification, we learned about the large-scale structures that galaxies can form. Here I will focus on the different types of galaxies and give you some tricks on how to observe them.

Celestial objects which are not individual stars outside our Solar System are referred to as deep sky objects. These nebulae, star clusters and galaxies come in different types and arrangements. Here’s a brief overview of their classification with a list of objects you’ll just want to photograph in your first observation!

Nebulae

The word nebula comes from Latin and means cloud: a nebula is an interstellar cloud of gas and dust.

The discipline of Astrophotography, as the name suggests, is the art of photographing celestial objects. A camera is mounted on the telescope to record the light coming through as “seen” by the telescope.