From Saturn, we are now going to journey inward to look at more new data on different moons. NASA’s Mars Odyssey, nineteen years after its arrival at the red planet, is still finding time to do science. For its latest work, it teamed up with the Sun to catch the moon Phobos fully illuminated in December, in eclipse in February, and coming out of eclipse in March. These images, taken with the Thermal Emission Imaging System (THEMIS) camera, which observes in the infrared and captures temperature information, allow scientists to see how quickly Phobos heats and cools as it orbits in and out of the Sun’s light. 

Under normal conditions, at least one side of Phobos is facing the Sun, and the world is being heated. During an eclipse, however, Phobos can hide in Mars’ shadow, radiate away built-up heat and cool off. The rate at which it cools is determined by its composition, and variations in heating and cooling can represent variations in composition from place to place. These images, combined with earlier data showing Phobos during its crescent phases, indicate that the 16 km across Phobos is fairly uniform and made up of very fine-grained material. Nothing exciting really, but sometimes reality isn’t exciting, and in 2020, I’ll honestly take all the “not very exciting” I can get.

More Information

NASA’s JPL press release