When the Hubble Space Telescope turned its lens on Mars in May 2016, it also spied the tiny moon Phobos swinging out from behind the planet.
Oval in shape and only 26 kilometres long, Phobos is one of the smallest moons in the solar system (though still bigger than Deimos, the other moon of Mars, which is only 12 kilometres across).
Phobos stays close to Mars in a tight orbit only 6000 kilometres above the surface that takes less than 8 hours to complete.
When the photos were taken, Mars and Phobos were some 80 million kilometres from Earth.