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Bruce Murray Space Image Library

Movie of Phobos and Deimos mutual event, Curiosity sol 351

Movie of Phobos and Deimos mutual event, Curiosity sol 351
Movie of Phobos and Deimos mutual event, Curiosity sol 351 This movie clip shows Phobos, the larger of the two moons of Mars, passing in front of the other Martian moon, Deimos, on August 1 2013, from the perspective of NASA's Mars rover Curiosity. The clip includes interpolated frames smoothing out the motion between frames from Curiosity's Mast Camera (Mastcam). Mastcam took images 1.4 seconds apart. With the interpolated frames, this clip has 10 frames per second. It runs for 20 seconds, matching the actual time elapsed. NASA / JPL-Caltech / Malin Space Science Systems / Texas A&M University

Here are the 41 original frames:

Transit of Deimos by Phobos, Curiosity sol 351
Transit of Deimos by Phobos, Curiosity sol 351 This movie clip shows the larger of Mars' two moons, Phobos, passing in front of the smaller Martian moon, Deimos, as observed by NASA's Mars rover Curiosity. The series of 41 images is shown at increased speed. The actual elapsed time is 55 seconds. The sequence was taken on August 1, 2011.Image: NASA / JPL / MSSS / Texas A&M

Most of the images were taken with some image compression, but ten of them were returned to Earth with lossless compression. Six of those ten are shown here:

Six frames from the occultation of Deimos by Phobos, Curiosity sol 351
Six frames from the occultation of Deimos by Phobos, Curiosity sol 351 These six images from NASA's Mars rover Curiosity show the two moons of Mars moments before (left three) and after (right three) the larger moon, Phobos, occulted Deimos on August 1, 2013. On each side, the top image is earlier in time than the ones beneath it.Image: NASA / JPL / MSSS / Texas A&M

Here is a comparison image, showing the apparent size of Phobos as compared to the apparent size of our Moon in our sky. Phobos is less than 1% the diameter of our Moon but is roughly 100 times closer to Mars than our Moon is to Earth.

Apparent sizes of Phobos and Deimos in Curiosity's sky compared to the Moon in Earth's sky
Apparent sizes of Phobos and Deimos in Curiosity's sky compared to the Moon in Earth's sky This illustration provides a comparison for how big the moons of Mars appear to be, as seen from the surface of Mars, in relation to the size that Earth's moon appears to be when seen from the surface of Earth. Earth's moon actually has a diameter more than 100 times greater than the larger Martian moon, Phobos. However, the Martian moons orbit much closer to their planet than the distance between Earth and Earth's moon.Image: NASA / JPL / MSSS / Texas A&M