The upper left panel diagrams the current positions of Mars and Earth in their orbits around the Sun. Note that Mars has a highly elliptical orbit compared to the Earth. For much of the time, Mars is too close to the Sun (as viewed from Earth) to be observed by Earth-based telescopes. For a QuickTime animation [1.1 MB] of the orbits of Earth and Mars and their relative positions through 2000 and 2001 click here
. The panel also shows the interplanetary trajectory of Mars Global Surveyor
. That spacecraft entered Mars orbit in 1997. Much information on the Martian surface and atmosphere is being gathered by the Global Surveyor which began the mapping phase of its mission in spring 1999.