The imaginary sphere on which all the objects in the sky appear is the:

The imaginary sphere on which objects in the sky appear to reside when observed from Earth. the arc that goes through the North point on the horizon, Zenith, South point on the horizon and Nadir. the imaginary line projected upon the celestial sphere that defines the apparent path of the Sun through the Earth's sky.

i believe the answer is  the similarity is that both are sacrifices which have the same purpose and sacrifice - jesus christ, but the difference is in offering of that sacrifice.

the similarity is that both are sacrifices which have the same purpose (repenting our sins) and sacrifice - jesus christ.  the difference is in the way of the offering that sacrifice. the sacrifice of jesus on the calvary is sacrifice of his actual living body and blood, but the sacrifice of the mass is the sacrifice of the jesus through bread (body) and blood (wine). in the sacrifice on calvary jesus was offered for us; while at mass he offers himself through us.