NASA Mars Curiosity: MastCam Image of Phobos moon taking a bite out of the Sun

NASA Mars Rover Curiosity's Mastcam captures the eclipse on Sol 37 (September 13, 2012). 

Credit: NASA/JPL-Caltech/Malin Space Science Systems

People often go to exotic locations to try and get the perfect view of a solar eclipse, but the Curiosity rover on Mars only had to look up to see an eclipse of a different kind.

Careful planning by the mission engineers ensured that the NASA rover had its cameras ready to capture the transit of Mars’s moon Phobos across the face of the Sun.

The partial eclipse occurred on September 13 (Sol (Martian day) 37 of Curiosity's time on the planet) and it took around 15 minutes for Phobos to graze the edge of the Sun.

The NASA Mars Rover Curiosity's MastCam camera is capable of filtering out some sunlight, meaning that it can safely look at the Sun.

Curiosity took more photos of the Mars' two moons crossing the face of the Sun on September 17.

Unlike a total solar eclipse on Earth, the moon Phobos is not large enough to completely block out the Sun’s disc.

Phobos is an irregular shaped moon measuring 27 by 22 by 18 kilometres, so it will only disrupt a portion of the Sun’s light.

In contrast, our Moon is 3,480 kilometres across, is 400 times smaller than the Sun and 400 times closer to Earth than the Sun, meaning that on Earth we can occasionally see a total solar eclipse.

Earth is the only planet in the solar system where a total solar eclipse can occur.

Mars’ moon Deimos is even smaller than Phobos, measuring 15 by 12 by 11 kilometres, and has a higher altitude, meaning that it will blot out far less of the Sun than Phobos when it transits the face of the disc.

Phobos has previously been caught in the act of eclipsing the Sun by the Opportunity rover in December 2010.

Opportunity’s twin, Spirit, also witnessed Phobos fade from the night sky as it passed within Mars’ shadow, in the equivalent of a lunar eclipse.

Phobos orbits Mars at a very low altitude of 9,400 kilometres, so it needs to travel fast in order to stop it from spiralling down towards the red planet.

This high speed means that it orbits Mars three times for every one rotation of the planet.