Well, as I said before, the Universe is BIG, I mean really, really BIG. It's bigger than you or I can imagine!
So, Deep Space really is a "catch all" for anything that is outside of our Solar System. It is synonymous with what we call the known Universe.
Our Solar System is big enough with all the planets, minor planets, moons, asteroids, comets, and human built spacecraft and debris. To demonstrate the size of our solar system, the National Optical Observatory has what they call, the thousand yard model. It's a bit dated, but in a nutshell, our solar system is about 1 light-year across, or about six million million miles. The nearest star from us is Proxima Centauri, which 4.2 light years from us.
The edge of the solar system varies depending on the strength of the Solar Winds which strengthen and abate on the sun's 11 year cycle. If generally accepted the Termination Shock varies from 85 to 105 AU. That is 85 to 105 distances from the Earth to the Sun. This is between 85 and 105 billion miles (give or take). (The discrepancy between the 100 billion just quoted and the 1 light year above is that the solar system is not static, nor particular circular. And the size depends on whom you ask.
But our Solar System is part of the Milky Way galaxy. This is a rather large galaxy, and extends about 100,000 light years across. The Milky Way can be considered deep space.'
But it's only one of millions of galaxies and other objects that we can see and detect in the known universe. The picture at the top of this window is a galaxy. It’s called the “Sombrero Galaxy" and the picture is a composite of images from the Hubble and the Spitzer Space Telescopes.
There are also clusters of stars that are close together that have not formed into galaxies. (Star Clusters).
There are also huge pockets of gas that are coalescing to form stars (Planetary Nebulae) and even huger ones that are slowly forming new galaxies (Nebulae).
Stars like everything have life cycles. There are young stars, middle-age stars (our sun is a middle age star), and old ones.
Depending on the type of star, when they are old, they can collapse or explode. Stars that collapse can become pulsars, and stars that explode can become nova or, if they are really big stars, they can explode and become SuperNova.
The problem is that all of the known material in the known universe (everything just mentioned), accounts for a small percentage of matter.
So what's left? Well, there is a great question, and to be honest -- while we are theorizing today -- we honestly don't know the full answer.
There are theories of dark matter, anti-matter, black holes. This branch of science is called "Cosmology". There is another branch of science which ponders the why of the Universe. How did this happen? This branch is called "Cosmogony".
All of this is "Deep Space".
The following pages explore some of the elements that make up "Deep Space" I hope you enjoy them.