You know that picture of the universe that reads you are here? I have always been intrigued by it and yet never truly realized what it meant. How big it all was. To give you an idea, let’s look at the solar system.
Our Sun is 150 million kilometers from us. But that’s pretty close. Pluto is 5.9 billion kilometers from us. Seems kind of far? Understand that our Solar system extends far beyond where any planets are. The furthest planet is a dwarf planet known as Eris that inhabits an area known as the Kuiper Belt which also includes Makemake and Haumea not to mention Pluto. So as you can see the Solar system is quite big. But a Solar system is not defined by its planets but by the reach of its gravity.
Housed in the furthest reaches of our humble Solar system is what is known as the Oort cloud. The Oort cloud is theorized to be a cloud of icy objects. It is the birth place of the long-period comets, or so we believe. But still we have not reached the end of the Sun’s dominance.
The Solar system ends, or rather the Sun’s gravity no longer has influence when you go out approximately 11 trillion miles; out past the Oort cloud to within two light-years of Proxima Centauri, the next nearest star.
Let’s take this further. Certainly there are other solar systems? Not exactly; Sol means sun so obviously the word solar refers to our star. So, technically there are no other solar systems. But yes, other systems exist and without the benefit of having been there, are very similar. At present it is suspected that there are 460 planetary systems that surround their stars. I say suspected because there may be more. In each of these systems there is at least one star and then a number of planets that are captured by its gravitational field. But that is just specific to our galaxy.
The Milky Way galaxy is a million trillion miles across. To put that into focus, it would take 10 billion years using our fastest plane to go from one side to the other.
So then how big is the Universe? Thanks to the Hubble space telescope deep field images have been taken of tiny regions of the sky. Just these tiny regions have shown the Universe to have thousands of galaxies. Based on that number, there are most likely hundreds of billions of galaxies
Are you feeling smaller now?