Do you say eclipse, occultation or transit? Certainly, Phobos\u2019s irregular potato-shape silhouette lends itself to more of a misshapen annular eclipse of the Sun. Orbiting Mars at just under 6,000 kilometers above the planet\u2019s surface, speedy Phobos takes just 7 hours and 39 minutes to orbit the Red Planet, faster than the planet rotates. It covers just a quarter of the apparent disk of the Sun at its maximum, and you would see it moving in real time, taking under a minute to cross the Sun\u2019s disk.<\/p>\n I know what you\u2019re thinking\u2026 is it safe for Percy to stare at the Sun? \u201cMastcam-Z used solar filters, much like eclipse glasses, to take the images,\u201d Mark Lemmon (Space Science Institute) told Universe Today. \u201cThe filter change was done before aiming at the Sun; the other order would not have resulted in damage, but that is a simple precaution. None of the instruments on the remote sensing mast can be damaged by the Sun when they are aimed that way and not in use.\u201d\u00a0 <\/p>\n The rovers witness other strange sights, including dusty blue sunsets<\/a>, and transits of the lesser of the two Martian moons, Deimos. The rovers have even been tasked to try and spot interstellar comet 3I\/ATLAS<\/a> on its close 29 million kilometer pass near Mars on October 3rd, 2025, and the close 140,000 kilometer pass of Comet C\/2013 A1 Siding Spring<\/a> past Mars on October 19th, 2014.<\/p>\n And just recently, Perseverance caught a bizarre occultation of the Earth<\/a> by Phobos. Mars is the only place in the solar system that you could stand on solid ground, and witness an asteroid-shaped body crossing in front of the Sun. <\/p>\n You\u2019ll note that Percy also caught a few sunspots on the solar disk. These sorts of observations come in handy when Mars is near solar conjunction on the farside of the Sun versus the Earth. Percy noted a massive sunspot region<\/a> in early May 2024, which later rotated into view for Earthbound observers and sparked an historic solar storm and auroral show about a week later. <\/p>\n The Science Behind the Image<\/p>\n Catching sight of Phobos crossing the Sun also allows researchers the chance to help and refine the positional orbits of the two Martian moons. <\/p>\n \u201cWe image the transits because they give precise measurements, better than 100-meter accuracy, of the location of Phobos at a specific instant,\u201d says Lemmon. \u201cThis constrains the Phobos orbit much better than can be done with the biggest telescope on Earth, since the rover is so much closer. The Sun makes for a great target as a reference for Phobos’ position. Better knowledge of the orbit is nice for planning: the first time transit imaging was done from Mars, Deimos was 40-kilometers off course using Viking-era ephemerides, but this problem is at the kilometer level now. However, the major purpose is to use the orbital evolution as a probe of the Martian (and Phobos’) interior. Tides raised by Phobos on Mars cause the orbit to change; the changes probe the flexibility of the Martian mantle. This is why we keep doing it, we want a long time baseline of these high-quality measurements. From the Spirit and Opportunity measurements, to Curiosity and now Perseverance, we are in the third decade of this experiment. In addition, orbiter teams have been working on this with images of Phobos’ shadow and occasional images of Phobos with stars from orbit.\u201d\u00a0 <\/p>\n This will prove handy when we want to approach, land on and explore the two moons. And that\u2019s coming right up, as the joint JAXA\/NASA Mars Moons Explorer (MMX) is launching on a H3-24L rocket from the Tanegashima Space Center in Japan this year on October 19th. The mission will approach Phobos in 2027, and return samples to Earth starting sometime in 2031. <\/p>\n Finally, watch for more Mars-based astronomy, currently underway. \u201cWe are in the middle of a nighttime Phobos imaging campaign that will be 5-6 nights in the end,\u201d says Lemmon. \u201cThree are done, with image data on the ground for two. These were designed to complement the solar images by observing Phobos near background stars in different parts of its orbit. These are intended to add to the above measurements, since a complete description of an orbit at a moment in time requires 6 parameters, and the transit only measures two at high precision (of course, it measure the one that is by far most important compared to how well known it is, which is how far along the orbital path Phobos is). For this, we use short exposures to see where Phobos is and long exposures to measure the star trails for a position reference.\u201d <\/p>\n Phobos was discovered by American astronomer Asaph Hall using the U.S. Naval Observatory\u2019s new 26\u201d refractor (the largest in the world at the time) during a favorable Mars opposition in 1877. Modern astrophotographers have managed to tease out the elusive moons from the glare of Mars near opposition season. Currently high in the pre-dawn sky in the astronomical constellation Gemini, Mars is once again approaching opposition<\/a> on February 19th, 2027. <\/p>\n![\"A](\"https:\/\/www.europesays.com\/us\/wp-content\/uploads\/2026\/08\/PIA26811-ezgif.com-optimize_20260831_164113.gif\"\/)
<\/a> A real-time view, of this month’s Phobos solar transit. Credit: NASA\/JPL-Caltech\/ASU\/MSS\/SSI<\/p>\n![\"Percy](\"https:\/\/www.europesays.com\/us\/wp-content\/uploads\/2026\/08\/e2-M2020_3IATLAS_clean-ezgif.com-video-to-gif-converter_20260831_164605.gif\"\/)
<\/a> Percy follows Comet 3I\/ATLAS on October 4th, 2025. Credit: NASA\/JPL-Caltech\/ASU\/MSSS.<\/p>\n![\"The](\"https:\/\/www.europesays.com\/us\/wp-content\/uploads\/2026\/08\/PIA26249-MarsPerseveranceRover-TransitDeimos-Video-20240119.webm.480p.vp9-ezgif.com-video-to-gif-con.gif\"\/)
<\/a> The start of a Deimos solar transit in 2024. Credit: NASA\/JPL-Caltech\/ASU\/MSSS.<\/p>\n![\"Sunspots](\"https:\/\/www.europesays.com\/us\/wp-content\/uploads\/2026\/08\/PIA26301_20260831_165002.jpg\"\/)
<\/a> Sunspots on the solar farside seen by Perseverance in 2024. Credit: NASA\/JPL-Caltech\/ASU\/MSSS.<\/p>\n![\"Phobos,](\"https:\/\/www.europesays.com\/us\/wp-content\/uploads\/2026\/08\/ZR0_1963_0841177767_178ECM_N0910606ZCAM01578_1100LMJ01_1200_20260831_171518.jpg\"\/)
<\/a> Phobos, imaged at night by Perseverance on August 28th, 2026. Credit: NASA\/JPL-Caltech\/ASU.<\/p>\n
![\"An](\"https:\/\/www.europesays.com\/us\/wp-content\/uploads\/2026\/08\/28889614167_e8db626997_c_1_20260831_164321.jpg\"\/)
<\/a> An astrophotographer image of Mars (over-exposed) Phobos and Deimos (annotated). Credit: Shahrin Ahmad.<\/p>\n