Replies

I wonder what sort of galactic distribution we're looking at here. Too close to Galactic Center, and the radiation is too great, along with relative scarcity of heavy elements. Too far away, and there's not enough heavy elements floating around to be scarfed up by newly-forming star systems. Galactic distribution of these possible planets may very well be donut-shaped. I wonder if we're at the median distance from the Center (at 33,000+/- light years away), or are we on one of the edges of the distribution? It may help any explorers to know where they're likely to find these worlds (going spinward/antispinward as opposed to coreward/rimward).

Even so, the volume of space to search in is likely pretty big. Anyone know the equation to find the volume of a torus? Now if these planets are plentiful enough, and relatively few of them have intelligent starfaring species on them, and the distances aren't too far between habitable worlds, then things will likely be relatively peaceful, with everyone having room to grow. On the other hand, if habitable planets are really scarce, I suspect that neutron bombs will be part of any terraforming package, to deal with the locals so we can take their real estate.

FROM: http://www.seds.org/messier/more/mw.html

Below we give some data for the Galactic Center (this and all following positions for epoch 2000.0):

Right ascension 17 : 45.6 (h : m)
Declination -28 : 56 (deg : m)
Distance 28 (kly)

Our Sun, together with the whole Solar System, is orbiting the Galactic Center at the distance given, on a nearly circular orbit. We are moving at about 250 km/sec, and need about 220 million years to complete one orbit (so the Solar System has orbited the Galactic Center about 20 to 21 times since its formation about 4.6 billion years ago). The Galactic North Pole is at

Right ascension 12 : 51.4 (h : m)
Declination +27 : 07 (deg : m)

Considering the sense of rotation, the Galaxy, at the Sun's position, is rotating toward the direction of Right Ascension 21:12.0, Declination +48:19. This shows that it rotates "backward" in the Galactic coordinate system, i.e. the Galactic North Pole is actually a physical South Pole with respect to galactic rotation. The coordinate data given here were extracted from the online coordinate calculator at Nasa's Extragalactical Database (NED).