Notes Toward a Better Understanding of Our Solar System

Sedna, discovered a decade ago, is a trans-Neptunian object (most likely a Dwarf planet) which may turn out to be "the first known member of the Inner Oort Cloud".   The red oval below depicts Sedna's extreme orbit about our Sun.

TNO's:  Trans-Neptunian Objects

Planetary bodies which orbit the Sun farther away than Neptune are known as Trans-Neptunian Objects, or TNOs.   I wrote about them last year in my Science & Speculation blog, Dark Side of the Wild.

Eris & Dysnomia

Eris is a Trans-Neptunian object classified as a dwarf planet, dwelling in the scattered disc.  It's moon is named Dysnomia.  

Oort Cloud >  Scattered Field >  Kuiper Belt >  Solar System >   (SUN)   < Solar System  < Kuiper Belt  < Scattered Field  < Oort Cloud  

It's important for us to try harder to visualize our solar system as it really is.  In order to do that, one must discard our old preconception of the "flat pancake of nine planets" orbiting our Sun, and get prepared to have your mind blown, because the real thing is far more staggering than any of us previously imagined.   Before we even begin trying to visualize what a galaxy is, we need to scale it down a bit, and focus on being able to correctly visualize a solar system, first.  

Parallax is used to gain depth-perception.  It is a displacement in the apparent position of an object viewed along two different lines of sight.  Stellar parallax is the effect of parallax on distant stars in astronomy.  Astronomy is the natural science that studies celestial objects and their evolution outside the atmosphere of Earth.  

Earth is the planet that we human beings all happen to reside upon.  There are five branches of natural science:  astronomy, biology, chemistry, physics, and the Earth sciences, which include ecology and geology.   Cosmology is the study of the universe as a whole, and in that regard, may be seen as a larger aspect of astronomy itself, one of the oldest sciences; the Egyptian monuments, for instance, are examples of some of the oldest astronomical artifacts.     

One may begin the exercise of visualizing our solar system from the Outside going inwards, or they may start from the Inside, going outwards from our Sun.   I think doing both is best, starting from the inner core of our solar system, the Sun.  But before we do that, we must remember that the star we revolve about daily itself was formulated back during that mysterious event of our solar system's birth.


Stars are formed from molecular clouds.   Our Sun is about 8.5 kiloparsecs from the center of our Milky Way Galaxy.   A parsec is 3.26 light years.  A kiloparsec (kpc) is one thousand times that, so three-thousand two-hundred and sixty-two light years.   To give us a better idea, our galaxy is measured as being somewhere in between 31 and 37 kiloparsecs in diameter, while being only one-third of a kiloparsec thick.   Here's a rough diagram (appropriated courtesy of the GNU Free Documentation License under Creative Commons):

The Globular clusters are spherical collections of stars which orbit a galactic core as a satellite.  

They exist within the galactic halo, that spherical region surrounding a galaxy which extends past the more visible and flattened disc-like portion more immediate to it.   There is both an inner halo and an outer halo; our Sun appears to be situated roughly where the inner halo ends and the outer halo begins.

 a 360 degree view of our galaxy

It's best to think of the cosmos as a nested set of spheres within spheres.  Our Milky Way Galaxy is a gigantic sphere of stars, wherein each star is nested, in turn, within a great spherical area of planetary bodies, such as our own Oort Cloud, for example.  At the core of which burns a single star.  

The Sun