As an undergraduate I worked in summers in soil science. Moisture
content in soils is conventionally expressed tersely as "%",
representing "per cent of dry weight". Soil moisture contents of
two or three hundred percent are frequently encountered, and the
moisture content can go even higher in peat. Since I have become
involved in astrophysics in my later years I cannot condemn the
use of conventions* and adherence to them even though they are
misleading to outsiders. This one, if it is a convention, is
truly disorienting to the outsider. Perhaps this book was not
meant for consumption by outsiders.
Leigh
* T Tauri stars are members of a class of objects early in the
process of gravitational accretion from a molecular cloud. The
archetype star of this class, T Tauri, is now thought not to be
a member of the class. The class continues to be called by that
name, however.
Many archaisms are retained in astronomy and astrphysics
precisely because the communication of information across
generations is *facilitated* by resisting changes. The quaint
system of stellar magnitudes we use is no longer needed since we
can count photons, or measure fluxes with bolometers, but we
still keep the system established more than twenty one centuries
ago by the Greek astronomer Hipparchus.