The dark side

There is more "dark matter" in the universe than there is normal matter -- the baryonic matter of which planets and stars are made and that is visible.   Dark matter's presence can only be inferred by its influence on visible matter -- it can't be seen.  And a lot of it has just been discovered:

Astronomers have discovered an object that appears to be an invisible galaxy made almost entirely of dark matter.

The team, led by Cardiff University, UK, claims it is the first such object to be detected.

A dark galaxy is an area in the Universe containing a large amount of mass that rotates like a galaxy, but contains no stars.

The galaxy is so large that if it were an ordinary galaxy it would be easily visible with an amateur telescope.

Astronomers say the discovery marks an important breakthrough because, according to cosmological models, dark matter is five times more abundant than the baryonic matter.