The Mars Science Laboratory we know as Curiosity recently witnessed a transit of Mercury. We can see the transit captured by the Curiosity Mast cam. This is the first solar transit of a planet viewed from another planet.
Mercury appears to be a faint dot in the images, faint because the planet takes up only about 16 percent of a pixel from such a distance. The two large dots are sun spots, those two spots are each about the size of Earth.
The next Mercury transit visible from Earth will occur on 09 May 2016. From Mars the transits occur more frequently. From Mars: the next Mercury transit will be in April 2015, A Venus transit won’t occur until 2030, and an Earth transit is way out there on the calendar – November 2084.
Note: I am posting this from a Wifi hotspot because my internet provider is failing me. I will try to post Wednesday but if you don’t hear from me you will know my connection is still down. Hopefully not.