An animated GIF of Mars's moon Phobos transiting across the sun looking like a blob
That slow-moving blob is Mars's moon Phobos transiting across the sun.
  • A "ring of fire" solar eclipse will take place on Saturday, October 14.
  • It promises to be a lot more eye-catching than last year's solar eclipse on Mars.
  • NASA's Perseverance Mars rover captured the eclipse, which was a little disappointing.

There are probably many interesting sights you could see from Mars. The Earth and its moon would appear as bright stars, for example. But a solar eclipse? Well, it's a little lackluster. 

Solar eclipses on Earth look the way they do because the size of the moon in the sky is nearly exactly the same size as the sun in the sky. So, when the two align, it's like two halves of an Oreo coming together, which makes for an especially amazing view. But Mars' moons are tiny compared to Earth's.

Neither of Mars' two moons, Phobos and Deimos, are nearly large enough to fully block the sun. Phobos looks about a third the size of Earth's moon, and Deimos is even tinier, appearing like a little speck compared to the sun.

As a result, Mars has what's called annular eclipses or transits, where you can still see most of the sun as one of the moons moves past.

Earth has its own annular eclipse due to start in southwestern Oregon at 9:13 a.m. PDT on Saturday, October 14. But as shown below, Earth's moon covers much more of the sun, just leaving the fringes visible which creates an effect that looks like a ring of fire, hence the nickname for this type of eclipse on Earth.

A side-by-side image of Phobos transitting the sun and a solar eclipse of Earth's moon with a bright ring of fire around the dark shape
Phobos is on the left and Earth's moon is on the right, both during solar eclipses.

The event on Earth promises to be breathtaking, especially for those in parts of the US where residents will see the moon overtake most of the sun. However, only watch with the proper protective eyewear.

The transit of Mars' moon Phobos across the sun

In 2022, NASA's Perseverance rover observed Phobos' transit. The image is far from breathtaking. Instead, it starts off looking a bit like an overhead projector where someone's finger is obscuring the image. 

Slowly, slowly the dark blob moves across the bright yellow ball. Eventually, the potato-shaped Phobos moves out of frame. The cosmic ballet continues. 

Solar eclipse on Mars.
Phobos crossing the sun as seen by NASA's Perseverance rover on Mars.

So this may not be Perseverance's finest photo. That's OK. It still has plenty of spectacular images in its portfolio. Its 23 cameras have picked up craters, sand dunes, dust devils, and much more on the red planet. 

And even if the transit itself wasn't as impressive as eclipses here on Earth, looking back at other images and video of similar events taken from other NASA spacecraft does highlight the impressiveness of Perseverance's technology.

For comparison, here's a shot of what Opportunity saw in 2004 and what the Curiosity rover saw during a 2019 eclipse:

The sun in three images with Mars's moons in transit going past, looking like small dark blobs
Deimos (top left) and Phobos (top right) in transit captured by Opportunity in 2004, and Phobos in transit (bottom) captured by Curiosity in 2019.

Perseverance landed on Mars on February 18, 2021. It should last at least another decade, so it will have plenty of opportunities to capture stunning photos and videos, eclipses and all. 

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