Curiosity Captures Sunset Eclipse And More On Mars

The Martian moon Phobos crosses in front of the Sun on March 26, 2019. Curiosity’s used its telephoto-lens camera, called Mastcam, equipped with a solar filter to capture the event which lasted only 35 seconds. It’s sped up here by a factor of 10. NASA/JPL-Caltech/MSSS

NASA’s Curiosity rover whipped out its eclipse glasses over the last few weeks to capture these amazing images of the moons Phobos and Deimos eclipsing the sun. The rover snapped pictures Phobos, the larger of the two planet’s moons at 16 miles (26 km) across, on March 26. Deimos (10 miles / 16 km) had its day in the sun on March 17.

Deimos transits the sun on March 17, 2019. The images have been sped up by a factor of 10. A typical transit last about 2 minutes. NASA/JPL-Caltech/MSSS

Phobos doesn’t completely cover the sun, so this would be considered an annular solar eclipse. Annular eclipses on Earth happen when the moon is farthest from the Earth and only covers the center of the sun, not the edges. At maximum eclipse, a brilliant ring (annulus) of sunlight surrounds the blackened moon.

Deimos is so small compared to the disk of the Sun, we call it a transit instead. It reminds me a lot of the dual transits of Venus we saw in 2004 and 2012. Through a solar filter Venus was plainly visible as a perfectly round black dot without a telescope; Deimos would be even easier. If we could watch from Mars it would appear 2½ times as big.

Phobos and Deimos up close. NASA

In addition to capturing each moon crossing in front of the sun, one of Curiosity’s Navigation Cameras caught the shadow of Phobos during sunset against the dusty Martian atmosphere. It’s a pretty incredible sequence. As the moon’s shadow passed over the rover during, it momentarily darkened the light. Notice the photo caption (below) reads “as Phobos was rising.” Phobos orbits so close to Mars that it completes an orbit every 7 hours 39 minutes. That’s fast enough to outpace the planet’s rotation, making Phobos rise in the west and set in the east!

Because Phobos orbits close to Mars and almost in line with its equator, annular eclipses of the moon are visible most days of the year from somewhere on the planet. The sun looks about a third smaller from Mars than it does from Earth (21 arcminutes vs. 30 arcminutes wide), because Mars is half again as far from the sun than the Earth.

The shadow of Phobos sweeps over NASA’s Curiosity Mars rover and darkens the sunlight on Monday, March 25. The sequence has been contrast-enhanced and sped up by a factor of four.
The image was taken after the Sun had dropped behind the local horizon, just as Phobos was rising and throwing its elongated shadow across the Martian surface. Dust particles in the atmosphere acted as a screen against which the shadow was projected. NASA/JPL-Caltech/MSSS

Besides just being amazing to look at these events help researchers fine-tune the orbits of the moons. Before the Spirit and Opportunity rovers landed in 2004 we only had an approximate idea of . The first time one of the rovers tried to get an image of Deimos in eclipse, the moon was 25 miles (40 km) off from predictions. The orbits of these small objects are always changing because of the pull of Mars, Jupiter and even the slight tug each moon exerts on the other. Every eclipse Curiosity observes adds precision to predicting the next. To date, eight Deimos and 40 Phobos events have been recorded.

Wouldn’t you love to see this? This is a simulation of the Phobos sunset eclipse on March 25, 2019 from Curiosity’s viewpoint in Gale Crater. Stellarium

For fun I used Stellarium to simulate the March 25th Phobos sunset eclipse. A nearby rise blocked the view for Curiosity, but if you had walked to the top you would have seen something like the image above. Wow …!

8 Responses

  1. kevan hubbard

    It’s a fantastic picture!on an equally fantastic note I believe that this April’s the month that Voyager 2 overtakes pioneer 10 as the second most remote man-made object from Earth.based on a rough idea of where pioneer 10 would now be as long as it has been hit by something….? although we must forget the rocket boosters of the pioneer and Voyager probes as it’s thought that some of them may be heading out of our star syestem too.

  2. Brian Rajala

    No doubt you are aware of the following article I read a few moments ago.

    My question is: How is it possible to capture meaningful picture images from Black Holes which will not allow light to escape?

    “” (Of all the forces or objects in the Universe that we cannot see—dark energy and dark matter—none has frustrated human curiosity so much as the invisible maws that shred and swallow entire stars like so many specks of dust, known as black holesClose the lightbox
    Of all the forces or objects in the Universe that we cannot see—dark energy and dark matter—none has frustrated human curiosity so much as the invisible maws that shred and swallow entire stars like so many specks of dust, known as black holes
    The world, it seems, is soon to see the first picture of a black hole.

    On Wednesday, astronomers across the globe will hold “six major press conferences” simultaneously to announce the first results of the Event Horizon Telescope (EHT), which was designed precisely for that purpose.

    It has been a long wait.

    Of all the forces or objects in the Universe that we cannot see—including dark energy and dark matter—none has frustrated human curiosity so much as the invisible maws that shred and swallow stars like so many specks of dust.

    Astronomers began speculating about these omnivorous “dark stars” in the 1700s, and since then indirect evidence has slowly accumulated.

    “More than 50 years ago, scientists saw that there was something very bright at the centre of our galaxy,” Paul McNamara, an astrophysicist at the European Space Agency and an expert on black holes, told AFP.

    “It has a gravitational pull strong enough to make stars orbit around it very quickly—as fast as 20 years.”

    To put that in perspective, our Solar System takes about 230 million years to circle the centre of the Milky Way.

    Eventually, astronomers speculated that these bright spots were in fact “black holes”—a term coined by American physicist John Archibald Wheeler in the mid-1960s—surrounded by a swirling band of white-hot gas and plasma.

    At the inner edge of these luminous accretion disks, things abruptly go dark.

    “The event horizon”—a.k.a. the point-of-no-return—”is not a physical barrier, you couldn’t stand on it,” McNamara explained.

    “If you’re on the inside of it, you can’t escape because you would need infinite energy. And if you are on the other side, you can—in principle.”

    A golf ball on the moon

    At its centre, the mass of a black hole is compressed into a single, zero-dimensional point.

    The distance between this so-called “singularity” and the event horizon is the radius, or half the width, of a black hole.

    The EHT that collected the data for the first-ever image is unlike any ever devised.

    “Instead of constructing a giant telescope—which would collapse under its own weight—we combined several observatories as if they were fragments of a giant mirror,” Michael Bremer, an astronomer at the Institute for Millimetric Radio Astronomy in Grenoble, told AFP.

    At its center, the mass of a black hole is compressed into a single, zero-dimensional point. The distance between this so-called “singularity” and the event horizon is the radius, or half the width, of the black hole
    In April 2017, eight such radio telescopes scattered across the globe—in Hawaii, Arizona, Spain, Mexico, Chile, and the South Pole—were trained on two black holes in very different corners of the Universe to collect data.

    Studies that could be unveiled next week are likely to zoom in on one or the other.

    Oddsmakers favour Sagittarius A*, the black hole at the centre of our own elliptical galaxy that first caught the eye of astronomers.

    Sag A* has four million times the mass of our sun, which means that the black hole is generates is about 44 million kilometres across.

    That may sound like a big target, but for the telescope array on Earth some 26,000 light-years (or 245 trillion kilometres) away, it’s like trying to photograph a golf ball on the Moon.

    Testing Einstein

    The other candidate is a monster black hole—1,500 times more massive even than Sag A*—in an elliptical galaxy known as M87.

    It’s also a lot farther from Earth, but distance and size balance out, making it roughly as easy (or difficult) to pinpoint.

    One reason this dark horse might be the one revealed next week is light smog within the Milky Way.

    “We are sitting in the plain of our galaxy—you have to look through all the stars and dust to get to the centre,” said McNamara.

    The data collected by the far-flung telescope array still had to be collected and collated.

    “The imaging algorithms we developed fill the gaps of data we are missing in order to reconstruct a picture of a black hole,” the team said on their website.

    Astrophysicists not involved in the project, including McNamara, are eagerly—perhaps anxiously—waiting to see if the findings challenge Einstein’s theory of general relativity, which has never been tested on this scale.

    Breakthrough observations in 2015 that earned the scientists involved a Nobel Prize used gravitational wave detectors to track two black holes smashing together.

    As they merged, ripples in the curvatures of time-space creating a unique, and detectable, signature.

    “Einstein’s theory of general relativity says that this is exactly what should happen,” said McNamara.

    But those were tiny black holes—only 60 times more massive than the Sun—compared to either of the ones under the gaze of the EHT.

    “Maybe the ones that are millions of times more massive are different—we just don’t know yet.”) “”

    Above from Google News

    1. astrobob

      Hi Brian,
      The hole would appear as a dark silhouette edged or partially enshrouded by bright gases and other debris surrounding it that are falling into the hole. As the material falls in, it releases lots of energy, causing it to glow.

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