“You can’t break even” refers to the

 Sunspots appear dark because they are:

 Another name for the manipulated variable is

The energy of a main sequence star comes from:

An elongated celestial object containing a coma, nucleus, tail, and a hydrogen cloud is a (an):

The frequency of an electromagnetic wave is a function of

Acceleration is defined as

A red rose

Copernicus restated the

You observe a star through your telescope.  If that star appears blue in color, it is