This composite image of Earth and Mars was created to allow viewers to gain a better understanding of the relative sizes of the two planets. The Earth image was acquired from the Galileo orbiter at about 6:10 a.m. Pacific Standard Time on Dec. 11, 1990, when the spacecraft was about 1.3 million miles from the planet during the first of two Earth flybys on its way to Jupiter. The Mars image was acquired by the Mars Global Surveyor in April of 1999.