[ 115 ] Earth and Space Science GED ® TEST SCIENCE FLASH REVIEW • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • Geocentric model Heliocentric model Earth Moon Mercury Venus Sun Mars Saturn Geocentric model proposed by Ptolemy (top) and heliocentric model proposed by Copernicus (bottom) With the two diagrams shown here, what can you determine about how Ptolemy and Copernicus saw the solar system?