NASA’s Mars rover Curiosity has captured several stunning videos of solar eclipses from the surface of the Red Planet.
Phobos transits the Sun’s disk, as seen by NASA’s Mars rover Curiosity on March 26, 2019. Image credit: NASA / JPL-Caltech / MSSS.
Martian moons Phobos and Deimos orbit in synchronous rotation with inclinations of only 0.01 and 0.92 degrees relative to the equatorial plane of Mars.
Thus, an observer at near-equatorial latitudes on the planet could occasionally observe solar eclipses by these tiny moons.
To date, there have been about 40 observations of Phobos eclipsing the Sun from Mars rovers Spirit, Opportunity or Curiosity; and there have been 8 observations of Deimos.
Besides being cool, these events also serve a scientific purpose, helping planetary researchers fine-tune their understanding of the orbits of the small moons.
“Before the Spirit and Opportunity rovers landed in 2004, there was much higher uncertainty in the orbit of each moon,” said Dr. Mark Lemmon, senior research scientist at Space Science Institute.
“More observations over time help pin down the details of each orbit.”
“Those orbits change all the time in response to the gravitational pull of Mars, Jupiter or even each Martian moon pulling on the other.”
Phobos was imaged on March 26, 2019 (the 2,359th Martian day, or Sol, of Curiosity’s mission). Deimos was photographed on March 17, 2019 (Sol 2350).
Phobos, which is as wide as 16 miles (26 km) across, doesn’t completely cover the Sun, so it would be considered an annular eclipse.
Because Deimos, which is just 10 miles (16 km) wide on average, is so small compared to the disk of the Sun, astronomers would say it’s transiting the Sun.
“These events help make Mars relatable,” Dr. Lemmon said.
“Eclipses, sunrises and sunsets and weather phenomena all make Mars real to people, as a world both like and unlike what they see outside, not just a subject in a book.”
In addition to capturing each moon crossing in front of the Sun, Curiosity observed the shadow of Phobos on March 25, 2019.
As the moon’s shadow passed over the rover during sunset, it momentarily darkened the light.
