When NASA’s Curiosity Mars rover landed in 2012, it brought
along eclipse glasses. The solar filters on its Mast Camera (Mastcam) allow it
to stare directly at the Sun. Over the past few weeks, Curiosity has been
putting them to good use by sending back some spectacular imagery of solar eclipses
caused by Phobos and Deimos,
Mars’ two moons.
Phobos, which is about 7 miles (11.5 kilometers) across,
was imaged on March 26, 2019 (the 2,359th sol, or Martian day, of Curiosity’s mission);
Deimos, which is about 1.5 miles (2.3 kilometers) across, was photographed on
March 17, 2019 (Sol 2350). Phobos doesn’t completely cover the Sun, so it would
be considered an annular eclipse. Because Deimos is so small compared to the
disk of the Sun, scientists would say it’s transiting
In addition to capturing each moon crossing in front of
the Sun, one of Curiosity’s Navigation Cameras (Navcams) observed the shadow of
Phobos on March 25, 2019 (Sol 2358). As the moon’s shadow passed over the rover
during sunset, it momentarily darkened the light.
eclipses have been seen many times by Curiosity
and other rovers
in the past. Besides being cool – who
doesn’t love an eclipse? – these
events also serve a scientific purpose, helping researchers fine-tune their
understanding of each moon’s orbit around Mars.
the Spirit and Opportunity rovers landed in 2004, there was much higher
uncertainty in the orbit of each moon, said Mark Lemmon of Texas A&M
University, College Station, a co-investigator with Curiosity’s Mastcam. The
first time one of the rovers tried to image Deimos eclipsing the Sun, they
found the moon was 25 miles (40 kilometers) away from where they expected.
“More observations over time help pin down the
details of each orbit,” Lemmon said. “Those orbits change all the
time in response to the gravitational pull of Mars, Jupiter or even each
Martian moon pulling on the other.”
These events also help make Mars relatable, 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.”
there have been eight observations of Deimos eclipsing the Sun from either
Spirit, Opportunity or Curiosity; there have been about 40 observations of Phobos.
There’s still a margin of uncertainty in the orbits of both Martian moons, but
that shrinks with every eclipse that’s viewed from the Red Planet’s surface.
Propulsion Laboratory, a division of Caltech, manages the Mars Science
Laboratory Project for NASA’s Science Mission Directorate, Washington. JPL
designed and built the project’s Curiosity rover.
Space Science Systems, San Diego, built and operates the Mastcam instrument and
two other instruments on Curiosity.
More information about Curiosity is at:
More information about Mars is at:
News Media Contact
Jet Propulsion Laboratory, Pasadena, Calif.