Planet X

Epigrammata LIII

Named for Hades, Pluto’s bright side is instantly recognizable. [source]

A confused legend in its own right
A name whose referent fell out of sight
Not an invisible shadow to Earth
Or identical twin but separate from birth;
Ruddy world, made mostly of ice
An ocean beneath, a sea without life --
Despite what we call "infath'mable cold"?
Is now not a planet, or so I am told
"X" stands for Ten, as was of old.