Hmm, regarding that Oort Cloud, here it shows it to be waayy outside of the Heliosphere and even out of the realm of the Heliopause. In other words where the sun's gravity actually ends and the Oort Cloud seems to be well in the realm of interstellar space.
http://coast.jpl.nasa.gov/interstellar/probe/introduction/scale.html

Then this one says:

Heliosphere.
The region in space that extends to the heliopause. The heliosphere is the cavity around the Sun in the local interstellar medium that is produced by the solar wind. The heliosphere contains most of the solar system, but not the most distant comets, such as in the Oort cloud.
http://www.mpi-hd.mpg.de/galileo/gloss.html#HELIOCENTRIC

Ok, but here, it says:

Oort cloud.
Reservoir of long period comets that occupies a spherical region of about 50,000 AU radius around the Sun.

http://www.mpi-hd.mpg.de/galileo/gloss.html#OORTCLOUD

Now, if it says in the first link that the Oort Cloud stretches at about 100,000 AU, why would it say that the OC is at 'about' 50,000 AU from the sun in that other site. I've seen conflicting info on this one.

By all means, let's find out! See pdf below:
http://interstellar.jpl.nasa.gov/interstellar/ISP_Space2K_v4.pdf

Marcia
*I don't know why, but I love this topic. *g* Even Elfven waves seem cool to me now.