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The NASA Curiosity rover has just spied the transits of the two Martian moons on the face of the Sun – including one after sunset.
Phobos, in transit on the face of the sun on Sol 2 359 (Tuesday, March 26).
NASA / JPL-Caltech / MSSS / Sequence: Dave Dickinson
In Andy Weir's book The Martian, the failed astronaut Mark Watney uses the rise and fall times of the Martian moons, Phobos and Deimos, as an approximate form of "calculating to death" to help him find his way. Last week, a clever observer browsing the recent images of the Curiosity rover revealed another equally interesting point: the innermost moon shadow, Phobos, as it glided silently across the face of the Sun – after bedtime of the sun.
A few days earlier, Curiosity had also captured a transit of Deimos and NASA has now released a series of images from both solar transits, as they are seen from the rover's point of view, at the same time. using solar filters connected to Curiosity's Mastcam.
Tiny Deimos scrolls on the face of the sun, seen from the surface of Mars.
NASA / JPL-Caltech / MSSS
"More observations over time help to pin down the details of each orbit," says Mark Lemmon (Institute of Space Science / Texas A & M University) in a recent press release. "These orbits change all the time in response to the gravitational pull of Mars, Jupiter or even each Martian moon pulling on each other."
Curiosity had already spotted such transits before, but this is the first time he sees the shadow of Phobos crossing the sky after the Martian sunset.
Chasing Shadow Moon on Mars
This unique phenomenon was first reported by user FredK at the unmanned space flight forum on March 26th. The images, taken by Curiosity's Navcam right, seemed to show a shadow crossing the sky, probably projected through a thin layer of dust suspended in the tenuous Martian atmosphere.
This piqued the interest of Jet Propulsion Laboratory Doug Ellison, who processed and stacked some of the images, and then posted the thread on Twitter (he is @doug_ellison). NASA then released an official sequence of the incredible show:
The shadow of Phobos glides to the right after sunset, in this view of Curiosity on Sol 2 358.
NASA / JPL / Caltech
"We knew it was going to happen (we had planned the sighting to capture it after all)," says Ellison, "but it was amazing to see someone outside to understand it … c & # 39; 39; was subtle enough in the raw audience .jpgs! "
Now, Curiosity is no stranger to irregular transits of Phobos. (WWe call them transits rather than eclipses, since the moon averages 12 minutes of arc and never completely covers the Sun with a 20.5 arc in diameter, as seen from the Martian surface.) of NASA have even used the observation of such events for down the precise orbits for the moon. Opportunities have also occurred in the past for tiny Deimos transits.
What's unique this time is that the final sequence captures the event after local sunset. Ellison described the circumstances for the rover for about 4:49 pm on March 26, in Universal Time (UT). and confirmed the transit. Heck, the same shade looks strangely like a redux of the shadow of the Moon seen crossing the sky during a total solar eclipse on Earth.
The shadow of the Moon of the Earth that slides into the sky during the 2017 total solar eclipse.
Alan Dyer / Amazing Sky
Phobos and his shadow also appeared on other images: NASA's Mars Global Surveyor orbiter saw the deformed shadow of the moon cross the Martian landscape.
The shadow of Phobos, seen by Mars Global Surveyor in 2000.
NASA / JPL / MSSS
And Mars Insight has also recently documented a distinct darkening when Phobos crossed the midday sun, seen from the location of the LG:
The shadow of Phobos softens the view of the Insight landing site.
NASA / JPL-Caltech
Insight should even detect small land tides raised by Phobos as it passes over his head.
Phobos orbits around Mars once every 7 hours and 39 minutes, just 5921 kilometers above sea level, above the Martian surface – the nearest moons around its host planet in the solar system. As it turns around the planet, a Mars-based observer will see Phobos rise Where is and put in the east – a really weird show.
The passage after sundown testifies to what attentive observers can find in the planetary images, with a little talent and patience. Maybe one day human eyes will see the subtle shadow of Phobos sliding over his head. Our best bet though is to travel on the slopes of Elysium Mons, where on November 10, 2084, we could spy on Phobos, the Earth and the Moon crossing the Sun at the same time.
Of course, there is a small uncertainty in calculating such an event so far; we promise to rerun the simulation from 2083. Let's see, I'll be there right now. . .
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