It Just Keeps Getting Bigger…

I’m always surprised at the things that go on in our galaxy, the Milky Way Galaxy.  In the past year or so, in the reading I do sporadically about the stars and planets and the cosmos, I ‘ve run across several articles about what has turned out to be the most common type of star in the Milky Way Galaxy.  This is the red dwarf star.

I’m not talking about red giant stars here, that’s a different matter altogether.  A red giant is a star in the last stages of its life, and it expands to be bigger than the orbit of Mars before it explodes in a huge supernova and spreads its innards all over the rest of the galaxy.  Like Betelgeuse is about to do.  No, I’m talking about a much smaller star, the red dwarf.  A red dwarf is smaller than our sun–much smaller in many cases–and unlike its larger cousin, isn’t in any hurry to explode.  Red dwarf stars are the most common type of stars in the galaxy, and may make up as much as 80 percent of all the stars in the galaxy.  (The latest estimates put the number of stars in the galaxy at 400 to 500 billion.)  But they’re so small and burn so weakly that you can’t see them by naked eye from Earth.  Some are so small, they’re not much larger than Jupiter.  When you look at the night sky, what you are seeing are the larger stars that burn white (or in some cases, red), like our sun.  We’ve known about red dwarfs for such a short time, they never showed up in most of the sci-fi movies or stories.  I don’t recall hearing anybody mention red dwarfs or see any whizzing by outside the windows of the briefing room on the Enterprise while Captain Picard was discussing the latest problem with his crew.

What’s even more interesting about red dwarfs is that we’re beginning to find planets around them.  Many, if not most red dwarfs may have planets, and they’re turning out to be small rocky planets that may be capable of harboring life.  A few caveats here, though.

Red dwarfs are so weak that the “habitable zone” where conditions are good for life developing on a planet’s surface is much, much closer to the star than the corresponding zone in our solar system.  Some planets orbiting red dwarfs circle around them in a matter of days, in fact.  Closer in, even in hours.  And red dwarfs have an annoying tendency to flare up every now and then, showering any planets in their system with X-rays and UV rays.  Not good for living organisms trying to get a foothold on a planet’s surface.  But the possibility exists that somewhere out there, among the billions of red dwarf stars is a small, relatively warm, moist planet with a bacterial, or perhaps slime mold-like organism on it, perhaps shielded under a rock or at the bottom of a lake, that is saying to itself, “I’ve come this far, I can go all the way.”  In short, the galaxy keeps getting stranger and stranger.  What will we find next?

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