NASA's Curiosity rover was able to capture never-before seen images of Mercury passing in front of the sun recently.

The images show Mercury as a faint dark spot moving across the sun. They are the first to demonstrate a planet's pass-by of the sun as seen from any planet other than Earth, according to NASA.

It is also the first instance when Mercury's photos have been captured from Mars as well.

"Mercury fills only about one-sixth of one pixel as seen from such great distance, so the darkening does not have a distinct shape, but its position follows Mercury's expected path based on orbital calculations," NASA said, in a statement.

Curiosity made the observations from Mars' Gale Crater on June 3, showing Mercury as two "sunspots" approximately the size of our planet.

A video clip, based on the images, shows the sunspots which appear to be moving at the pace of the sun's rotation, which is much slower than Mercury's movement, according to NASA.

NASA recently confirmed that on May 9, 2016, Mercury can be seen transiting the sun from Earth, while a similar incident will be visible from Mars as early as April 2015.

A Venus transit of the sun will be visible from Mars sometime in August 2030, which will be followed by a transit of the sun by Earth in November 2084, according to NASA.

"This is a nod to the relevance of planetary transits to the history of astronomy on Earth," Mark Lemmon of Texas A&M University, College Station, and a member of the Mastcan science team, said in the statement. "Observations of Venus transits were used to measure the size of the solar system, and Mercury transits were used to measure the size of the sun."

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