NASA's Mars rover Curiosity has taken on a second job - moonlighting as an astronomer.

Last week Curiosity outfitted its high-res camera with protective filters, and snapped pictures of the sun as Phobos, one of Mar's two small moons, sailed by.

It was a tricky shoot.

Phobos and its sister moon Deimos are closer to Mars than our moon is to Earth, so they shoot across the sky pretty quick.

Fortunately Curiosity had a partner in the project - it's sister rover Opportunity on the other side of Mars.

Between them they captured some great photos of the eclipse.

But it isn't all about pretty pictures: the images should also help scientists learn more about Mars's internal structure.

Like Earth's moon, Mars' moons have some gravitational pull that slightly change the planet's shape.