For the past decade, astronomers thought they had a reasonable answer to that question. Around stars like our Sun, the two dominant planet types are sub-Neptunes, worlds resembling a shrunken Neptune, with thick gaseous envelopes and super-Earths, rocky planets up to ten times the mass of our own. Surveys had found them everywhere, orbiting star after star, and the assumption quietly took hold that these planets must be equally widespread across the Galaxy as a whole. New research from McMaster University has just demolished that assumption. The problem with the earlier picture was that the stars and planets studied were not fully representative of the plethora of stars in the Galaxy. Sun like stars for example, for all their familiarity, are actually a minority in the Milky Way. The most numerous stars in our Galaxy are mid-to-late M dwarfs (red dwarfs), small, dim, and cool, ranging from just eight to forty percent the size of our Sun.…