Why is it useful to know the density of a celestial object?

Because it is important to know the composition of the object

Density is the ratio of the mass of a sample to the volume occupied by that mass, and expresses how much mass there is per unit volume of a given portion of matter. Density is a physical property of extreme importance in the characterization, identification and use of substances or materials.

length of the cultivating season was not a problem of new england agriculture

answer; i believe that the correct answer is,lies(political rhetoric);