A mosaic of three separate images taken by Viking 1 on October 19, 1978. The large crater (mostly in darkness) on the upper left is Stickney.
It is thought that the impact which created Stickney was so severe that it nearly broke up Phobos. Radiating grooves can be seen around Stickney.
Stickney could be seen with the naked eye from the surface of Mars.[2] It is at the middle of the left edge of Phobos's face, on the Mars-facing side. It is located at 5°S 55°W on Phobos.
It has a smaller, unnamed crater within it, resulting from a later impact.
References 
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- ↑ https://en.wikipedia.org/wiki/Stickney_(crater)
- ↑ Angular Size: With a diameter of 9km and a distance of 9250km, we get 9/9250*206265 = 200". An object needs to 60" to be resolved by the naked eye.
