WIMPS and MACHOS

The Universe is not heavy enough.  This finding comes from watching galaxies rotate.  They are rotating faster than they ought to be.  Speed of rotation is something Newton worked out, and it's taught in sophomore physics.  Using Newton's math, one can observe the period and diameter of a satellite's orbit, and compute the mass of the primary quite exactly. The stronger the gravitational field, the faster an object has to move, to create enough centrifugal force to keep from falling. 
   They figured the mass of  galaxies by counting the stars in them on the assumption that the mass is all/mostly stars, which shine by their own light and can been seen at great distances.  Assume the astronomers took a few short cuts, like counting the stars in a tiny patch of galaxy and extrapolating the total number of stars in that galaxy. When they computed the mass required to account for the observed rotation speed, they came up short.  The needed mass was two, three, and more times the observed (luminous) mass of the galaxy.  And so, everyone, astronomers, physicists, science writers and so on, accept that there is a LOT of dark (non luminous) matter in the universe.  Like more dark matter than luminous matter. Most of the universe is dark matter.
   The obvious question " What is this dark matter?"  came up with two possibilities.  The universe could be rich in an as yet undiscovered particle. Something as hard to detect as a neutrino but with mass like a proton. These were dubbed Weakly Interacting Massive Particles" or WIMPS for short.  The physicists loved WIMPS,. It gave them a new particle to hunt for.  Now that the Higg's Boson  has been claimed, there are a lot of accelerators and accelerator physicists looking for something else to do.
  The other possibility is simply ordinary matter that is not stars.  Like the earth, or Jupiter.  Jupiter is an interesting case.  It is a near star, it's pure hydrogen, and it radiates more heat than it absorbs from the Sun.  Jupiter must be running low level nuclear fusion way down at its core.  If Jupiter had been a little larger, it would be a star and shine by its own light, and we would live in a binary solar system.  Binary systems are pretty common out there in the galaxy, say 10% or more.
   Stars are formed by a not yet well understood process of gravitational attraction.  Plenty of stars large enough to shine were formed.  You can see them in the night sky.  But, if the process can yield large stars, why can it not yield a lot of small ones like Jupiter? Ones too small to shine.
  This is the Massive Compact Halo Object, or MACHO.   And, this year, somebody detected one.  It turned up in the search for extraterrestrial planets.  It was a Jupiter sized object, way out in deep space, all by itself.
   Right now, WIMPS are ahead, at least they get a lot of good press, and MACHO's are not talked about much.  Me, I kinda like the MACHO idea.  It's perfectly plausible and it doesn't require new invisible and undetectable particles.