Figure: The Martian moons Phobos and Deimos

Image 1 Caption: The Martian moons are Phobos (mean radius 11.1 km) and Deimos (mean radius 6.2 km) are shown to-scale in size and with Mars which means they are NOT visible without doing a triple-click to see the enlarged image. Although the image is to-scale, it may be a collage and NOT a single image. The vertical of the image is, more or less, Martian east-west.

Further explication:

1. The Martian moons are both irregular in shape because they are too low mass to have been pulled into spherical shape by self-gravity.

2. Both moons are tidally locked to Mars which means they have a near side always facing mars and a far side always facing away from Mars (Wikipedia: Moons of Mars: Characteristics). Most large and/or close-host-planet moons in the Solar System are tidally locked to their host planets (Wikipedia: Natural satellite: Tidal locking). In fact, Most large and/or close-host-planet moons throughout the observable universe must be tidally locked to their host planet.

3. The commonest origin theory is that the Martian moons are captured asteroids, but rival theories exist (see Wikipedia: Moons of Mars: Origin).

4. The Martian moons were discovered in 1877 during the same FAVORABLE opposition that resulted in emphasis given to the possible existence of the Martian canals. They were discovered by Asaph Hall (1829--1907) at the US Naval Observatory (USNO) in Washington, D.C..

5. Jonathan Swift (1667--1745) (in Gulliver's Travels (1726, 1736)) and Voltaire (1694--1778) fictionally predicted that Mars would have 2 moons. Craters on Deimos are named for Swift and Voltaire. And who can forget that immortal yarn The Secret of the Martian Moons (1955) by Donald A. Wollheim (1914--1990). Vote now for Crater Wollheim.

   

6. Image 2 Caption: The Martian moons are Phobos (mean radius 11.1 km) and Deimos (mean radius 6.2 km) are shown to-scale in size in collage.

   The image is false color in order to bring out details.

7. See the NASA video NASA: The Moons Of Mars, August 27, 2013, ID:11326 | 0:22: Authoritative: In this time-lapsed NASA video assembled from images taken by the Curiosity Mars rover, we see Phobos (mean radius 11.2667 km) (the larger of the two Martian moons) eclipsing Deimos (mean radius 6.2(2) km) (the smaller and much more distant of the Martian moons).

8. There is nothing unusual or fundamentally important about eclipses. They happen throughout the Solar System and the observable universe and their physical effects are of little importance. However, humankind has just always been awed by those that are obvious to us (i.e., lunar and solar eclipses) and that to ancient societies were often seen as irregular and ominous.