Convert from spat to yoctometer

Unit Definition (spat)
The spat is an informal unit of distance formerly used by astronomers. The spat is equal to the terameter (Tm, or 10E12 meters). This is equivalent to about 6.6846 astronomical units. The origin of this usage is not clear; "spat" may be an acronym for "space unit" or "space-time".

Unit Definition (yoctometer)
The yoctometre (or yoctometer), symbol: ym, is a decimal fraction of a metre, from the International System of Units. One yoctometre is 1x10-24 (1e-24) in scientific notation. Very small!