Shells

Let me drop some more perspective on you. Here's our old friend, the Oort Cloud. Picture billions upon billions of icy little comets tumbling around in a vast sphere, such that our entire solar system is enshrouded in a cloud of ice. A shell, like the electron shell.

It's big - extending almost a light year in all directions from the Sun. And then as you see, far closer in, is another sphere, or shell, of icy bodies, but also rocky bodies too - like Pluto. The Kuiper Belt, another shell - also like the electron shell.

So again picture this from far away in space, looking towards the Sun. First a giant cloud of white ice, floating lazily in a vast sphere. And another sphere of ice and rock far within that, and then tucked inside that shell are planets, and a star.

Every star with planets probably has something similar. And so now look up into the dark sky and picture every star you see as a white egg of ice shells, within beats the bright nucleus of a galactic atom. Together these atoms join with vast clouds of gas to create galaxies, and galaxies join other galaxies strung along in necklaces of dark matter, grouping in vast clouds of millions of galaxies, stretching.... forever?

Is a shell forever?

You Oort to Know

The Oort cloud is a sphere of ice and rock and lots of other frozen stuff that marks the limit of our Sun's gravitational pull. It is hypothesized that comets come from the Oort cloud, getting knocked out of it in any number of ways, and then getting drawn in towards the Sun (and it is likely Earth's oceans came from Comets - thus, the Oort cloud). It is also HUGE - another lesson, folks: Everything's bigger than you can imagine. The Oort cloud represents the end of our Solar System - our home - and it stretches out to 1 light year in a circle around the sun. For perspective, our nearest stellar neighbor, Proxima Centauri, is 4 light years from the Sun. Here's another picture that might give you a sense of the scale:

As you can see, what we traditionally think of as the Solar System - the planets in their orbits - is really, really small compared to what is actually our Solar System - the Oort Cloud and everything within it. So much bigger, in fact, that there's a growing realization there might be other planetoids, like Pluto, hiding out there, hitherto undetected. One such new plaentoid was found recently, named Sedna:

Read the above picture from upper left (inner solar system) to upper right (outer solar system, with Sedna indicated), down to lower right (Sedna's orbit as compared to Neptune and the Gang) than lower left (Sedna's orbit as compared to the Oort Cloud), each frame encompassing the previous. 


If I've done my job, this should all remind you of something, but if not, check back in in a few days - payoff's a'coming.