The orbits of the planets Earth and Mars provide a geometric line up that is out of this world! Every 26 months Mars is opposite the Sun in our nighttime sky. Since the repair of the Hubble telescope in 1993, Mars has been at such an "opposition" with the Sun six times. A color composite from each of the six Hubble opposition observations has been assembled in this mosaic to showcase the beauty and splendor that is "The Red Planet."
This mosaic of all six globes of Mars shows relative variations in the apparent angular size of Mars over the years. Mars was the closest in 2003 when it came within 35 million miles (56 million km) of Earth. The part of Mars that is tilted towards the Earth also shifts over time, resulting in the changing visibility of the polar caps. Clouds and dust storms as well as the size of the ice caps can change the appearance of Mars on time scales of days, weeks, and months. Other features of Mars, though, such as some of the large dark markings, have remained unchanged for centuries, and will probably look essentially like this for the next few millennia.
Acknowledgment: J. Bell (Cornell University) and M. Wolff (Space Science Institute)