NASA’s Mars Perseverance rover shared incredible footage of the moon Phobos crossing in front of the sun. The video may look like something you could record with a light source and potato, but it’s still actually an amazing capture. And one that NASA scientists will use to learn more about both Mars and Phobos. The Curiosity, Spirit, and Opportunity rovers have previously witnessed the event. But Perseverance’s high resolution and color capabilities make this Mars solar eclipse video even better.
But Is it Really a Mars Solar Eclipse?
A solar eclipse is when a moon crosses the path of the sun. On Earth, total eclipses are possible, but only because of a random quirk. The sun is about 400 times larger than the moon and also 400 times farther from Earth. So they look relatively the same size in our sky.
This coincidence does not apply on Mars. The moons are too small to completely fully cover the sun, so there are no total eclipses. So is this actually a transit instead? The terminology is unclear, even on NASA’s website. Perseverance (or whoever runs the Twitter account) called it an eclipse, rather than a transit. What is clear is that this is a cool phenomenon and the Perseverance rover has incredible technology.
The Moons of Mars
Mars has two moons, Phobos and Deimos, both of which look very different from our own. Planetary bodies require a certain mass to be rounded by gravity and these are both too small. They look more like asteroids, lumpy and full of craters. They may even be former asteroids that Mars’ gravity captured and pulled into orbit. We don’t actually know how they came to be there!
Phobos is really close to Mars, its orbit is 3,700 miles above the planet’s surface. In comparison, our moon ranges between 225,000 to 250,000 miles away. Phobos completes each rotation in under eight hours. Which means when everything lines up for an eclipse/transit, it happens multiple times in a row.
Truly fascinating. I zoomed in with my Mastcam-Z camera on a Phobos solar eclipse. This detailed video can help scientists on my team better understand the Martian moon’s orbit and how its gravity affects the interior of Mars, including its crust & mantle. https://t.co/jVdJ4UwhDx pic.twitter.com/q45HwKwLIS— NASA's Perseverance Mars Rover (@NASAPersevere) April 20, 2022
If you can’t get enough space content, here’s Perseverance’s video of Deimos. It looks more like a bright star because Deimos is both smaller and farther from Mars. Or check out this video that replaces our moon with planets to show a size comparison.
Featured Image: NASA Jet Propulsion Laboratory
Melissa is Nerdist’s science & technology staff writer. She also moderates “science of” panels at conventions and co-hosts Star Warsologies, a podcast about science and Star Wars. Follow her on Twitter @melissatruth.