Notes

Just a few things:

Poynting–Robertson drag: solar radiation will cause dust grains to spiral inward.

From the perspective of the dust grain, solar radiation appears to be coming from a slightly forward direction. This is the aberration of light; at the instant of any observation of an object, the apparent position of the object (the sun) is displaced (see figure below). Absorbing this light leads to a force component against the direction of movement.

From the perspective of the solar system (the other reference frame), the dust absorbs sunlight in only the radial direction and its angular momentum is unchanged. However, by absorbing the photons it gains mass, and to conserve angular momentum L = r x mv, the dust must drop to a lower orbit.

Light from location 1 will appear to be coming from location 2 for a moving telescope due to the finite speed of light, a phenomenon known as the aberration of light.

Paucity of intelligent life: part of this
We've highly overestimated intelligent, technologically advanced life (they would have come knocking). Why? One reason is that there is no evolutionary pressure to gain technology; another is that the lifespan of an 'advanced' civilization is perhaps on a very small order, and that they die out quickly.

Heliosphere map and IBEX: listen to this short 2009 broadcast

The sun's corona boils off into space, producing the solar wind of hot ionized gas, flowing out at a million miles an hour. This inflates the bubble of the heliosphere. IBEX, the interstellar boundary explorer, measures neutral particles that propagate in from the outer reaches of the heliosphere, about 10 billion miles out. In the space between the termination shock and the ISM, the gas becomes heated and slower. The neutralized particles are produced in this interaction region between solar-material and outer-space material. IBEX took 6 months to map these particles.

It was expected to see a variation in the particle flux, relatively small (tens of percent) and to vary over  large angular ranges. Instead, there is very narrow 'ribbon' in the sky, where the flux is two or three times of anywhere else. The ribbon appears to line up with the external magnetic field (outside of the solar field) where it drapes around and squeezes hardest on our heliosphere. Most likely, the ribbon of incoming particles is correlated to the higher density of particles outside.

Pretty awesome stuff. :P