13 Most Iconic Science Pictures Ever Taken

5. Sunset On Mars

In 2005, NASA's Mars rover, Spirit, allowed us to glimpse this everyday occurrence on a completely different planet for the first time in human history.

Images such as this allow NASA scientists to determine the composition of the Martian atmosphere. Twilight lasts for many hours on the red planet, due to the abundance of high-altitude dust in the atmosphere scattering the sun's rays long after it has sunk below the horizon, but the thin atmosphere means that the sunsets and sunrises are less colourful that back home.

Perhaps this will be a common sight for future colonists, but for now this is one of the few images of an alien sunset we have.