Credit: NASA, ESA, and Z. Levay (STScI)
While photographing Mars, NASA's Hubble Space Telescope captured a cameo appearance of the tiny moon Phobos on its trek around the Red
Planet. Discovered in 1877, the diminutive, potato-shaped moon is so small that it appears star-like in the Hubble pictures. Phobos orbits Mars in just 7 hours and 39 minutes, which is faster than Mars rotates. The moon's orbit is very slowly shrinking, meaning it will eventually shatter
under Mars' gravitational pull, or crash onto the planet. Hubble took 13
separate exposures over 22 minutes to create a time-lapse video showing the moon's orbital path.