Mars Retrograde 2018

Roughly every 2 years, as the Earth approaches and overtakes Mars in its orbit, Mars appears to move backwards in the sky for several months. This apparent backwards, or retrograde motion puzzled early astronomers, and is one of the reasons they named these objects ‘Planets,’ as Planet comes from the Greek word for ‘Wanderer.‘

To create this piece, images of Mars were taken a week or so apart, to highlight how it appears to slow, reverse its direction across the sky and then return to its normal movement, over the course of several months.

However, due to the slight difference in Earth and Mars’ orbital inclination around the sun, Mars doesn’t move in a straight line across the night sky, it follows a more complex path, like the beautiful loop shown in this image.