Wired online reports that the American Astronomical Society has produced a report following its conference on 8-12 January 2012.

One section seemed to me of particular interest to the explorers of that galaxy in the 41st Millenium:-

Microlensing reveals a best estimate of the Milky Way's planetary population

There are three ways to hunt exoplanets. The radial velocity method measures how much a star wiggles due to a revolving planet's gravitational force. The transit method measures periodic blinks in the brightness of a star, suggesting the yearly orbit of a planet.

The third, gravitational microlensing, is the hardest to pull off. You need two stars in a straight line towards Earth so the light from the background star is amplified by the gravity of the foreground star, turning the whole set-up into a giant magnifying glass.

It's the hardest to do, but brings out smaller planets that are similar to Earth and Mars. In a six-year hunt, a team of astronomers witnessed 40 of these microlensing events, and spotted planets in three of those instances. A good haul, says astronomer Uffe Graae Jorgensen.

Take the exoplanet statistics we've found with all three methods so far and the conclusion is stunning: the Milky Way could host 100 billion alien planets -- 10 billion of which could be Earth-like worlds. Invoking the Drake Equation at this point is advised for anyone wanting to work out how these figures translate into estimates of worlds that could host intelligent life.

Pretty interesting stuff, but I think 10 billion worlds is too high a number. That means 1 out of 10 planets is Earth-like. I guess the question is: what does Earth-like mean? Does it mean that it is made of dirt instead of ice or gasses? Does it mean that it has life? If it were the first definition, I would say that could be plausable. If the second . . . no.

Then again, of the nine planets in our solar system (**** you scientists, I still say Pluto is a planet), one has life, and another may have had life at some point in time. Perhaps it is possible that there is a lot of life out there.

In any case, there are somewhere between 200 and 400 billion stars out there, so the fact that the Imperium of Man encompasses one million worlds (some of which are possibly only moon bases) is entirely plausible.

thesavage said:

even more so when you consider how many of those worlds are airless rocks, or asteroid belts, etc

Now, just work out the probabilty of a habitable planet having life and the probability that any of that life is "intelligent" and that any of that life is sufficiently intelligent that it can be detected/communicated with and you're good to go. As Drake was concerned with DETECTABLE civilizations, would humanity even fit his bill? One of the problems with Drake's equation is that the constants you feed into it still are largely in flux, and some would vary with our own technical capabilities to actually detect that life.

For extra credit, work out how many Eldar souls Slaanesh will eat between now and the time we make it to our nearest stellar neighbor.

Actually, Drake based his Detectable off of the technological abilities and output of the human race at the time. We're quite a bit more advanced now and spewing out even more detectable transmissions.

So yes, we apply.