Curiosity looks up, spies Martian double-mooning As Curiosity trundles across the Martian surface, the bulk of NASA's interest has been focused downwards at the ground, but the rover has also been looking up and has captured some remarkable video of the two moons of Mars overlapping each other overhead. The images captured by the telephoto lens in Curiosity's Mast Camera …
There have been tides for all those years, just not the liquid water ones that you're thinking of. The Earth's Moon actually stretches the solid Earth, the oceans and the atmosphere. The rock tides are so small you can't see them without instruments, the air tides are also are invisible to the unaided human observer, so we tend to focus on the water tides as 'the tides'. But the other ones are still there.
Similarly for Phobos and Mars. There is no liquid water to make water tides, but there are both rock tides and air tides. And as already shown above, they're actually comparable in size to the ones we have here.
Or in other words, the forces are there and they will do things; the mere absence of liquid water won't make them go away.
The tidal effects still exist, even though there are no seas to rise and fall. Our moon is ~6 million times the mass of Phobos, while Phobos is ~40x closer to its planet (less than 10,000 km), which means the tides (inversely proportional to distance cubed) are about 100 times less.
Even though Phobos is a bit of a flyspeck, because it's so close to Mars it actually appears about one quarter of the size of Earth's Moon from the surface there.
Fun Fact: Earth's Moon, Luna, is moving away from Earth at the rate of about 1.5" per year.
This means that early in Earth's history Luna orbited more closely and faster, and the Earth's days were shorter, than today. This has been corroborated by studies of growth-rings in (hundreds of millions of years old) fossil corals.
Actually, that should be:
the tides ... are about 100 25 times less
and
appears about one quarter one half of the size of Earth's Moon
Phobos is so close that Mars's radius significantly affects the answer. Also the tides are much stronger on the side of the planet facing the moon (unlike on Earth where the tides 12 hours apart are of similar strength).
Deimos is both smaller and much further away, so the tidal effects it generates are swamped by the eccentricity of Phobos's orbit.
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Occult originally just means 'hidden' (e.g. occult knowledge), but in astronomy it means a body being hidden by another one passing between it and an observer. Occlude means to obstruct completely - e.g. the sky is currently occluded by cloud.
Sorry, if my irony detector is malfunctioning :)
"Yo Dawg, I herd you like moons, so I put an extra moon in your lunar eclipse so you can hide one moon while you look at another moon."
...and if you look really closely, you can see two imps and a Hell Knight drinking the blood of some UAC employees while some lone grunt with a chainsaw in his hands looks on looking rather angry.
Steven "Yeah, I know it's probably not a proper lunar eclipse but I don't know how to descrive it to fit that meme so why don't you come up with something better. Although I hope you like the Doom reference" Raith
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