Planets are celestial bodies orbiting the Sun. Thus, we see them moving from west to east over the starry background.
But, sometimes, we can see a planet stopping and coming back, from east to west. This is possible only with external planets as Mars, Jupiter, Saturn, Uranus, Neptune or Pluto, that orbit the Sun at greater distances than the Earth. Orbiting faster around its smaller orbit, our planet goes ahead them, and we see their trajectory as a big loop.
During the first half of 1997, Mars drawed over the sky a big loop during its retrogradation. On February 6th, 1997, it stopped its direct path from west to east, starting a wide retrograde loop to the west, from the constellation Virgo to Leo. On April 29, it stopped again and resumed its normal direct path eastwards.
We obtained a series of snapshots of Mars between January and June, 1997. Each exposure was 8 seconds long with a CCD electronic camera and a 50 mm photographic lens piggybacked on a telescope provided with an equatorial mount, in order to avoid stars appearing as trails. The final image is a mosaic of two frames, 12° wide each.