Panic, Fear, and Planetary Science…

Good Woden’s day, all.

So – last week I posted about Earth’s moon out of, basically, laziness – so it seemed only fair that I talk a bit about the far more interesting and exciting topic of The Moons of Mars! (capitalized for excitement and because I’m in charge.)

Mars has 2 (two) moons PHOBOS, and DEIMOS – they’re small and junky-looking and all cratery and kind of useless. But what they lack in sizeable awesomeness, they more than make up for in speed, weirdness, and eventual destruction… so that’s nice.

Let’s meet Deimos… the outer moon. The Greek mythology ‘Deimos’ was one of the sons of Mars and Venus and it’s also the Greek word for ‘panic’… so you Douglas Adams fans will now have an even nerdier way of telling people to chillax.

Deimos is about 12 km across and looks like an asteroid – all pitted and cratered, actually – this is it right here:

Pretty dull, right? Well the reason for that is most likely because Deimos and Phobos (the other moon) are both probably asteroids that got pulled in by Jupiter’s gravity, which slowed them up enough to be captured by Mars and forced into a somewhat stable orbit. So the moons of Mars, unlike our own moon – are more or less unwilling captives.

Seen from Mars, Deimos is very tiny and would almost look like just another star in the sky because it’s very far away, and it moves slowly (also due to distance) orbiting the planet once every 30 hours or so – which means the from the surface of mars it would take a little over 2 days for it to rise and set.

Now… on to Phobos!

That is Phobos.

In Greek, Phobos means ‘fear’ and was also a son of Mars – and fear is just about right for a couple good reasons.

Phobos is about twice the size of Deimos – 22km across – and closer to its planet than any other moon in the solar system, and being so close means it moves wicked fast – rising and setting in about 4 hours and a bit. If you were standing on Mars you would see the moon rise and fall twice everyday and your werewolves would be f–king exhausted.

In keeping with its brother Deimos, Phobos is very much like an asteroid – all pitted with lots of high porous craters – which have led to some interesting speculation about it – including that it might be hollow, or that it might have a huge frozen water reservoir inside somewhere… both of which seem pretty far fetched, but so do a lot of things, so who knows?

The larger moon of Mars has another interesting aspect, which is that in 11 million years it will be destroyed.

There we go… that woke you up, right?

Phobos, just like we discussed with Earth’s moon, is subject to tidal friction with the planet – but unlike our Moon, which responds by moving away and slowing us down, Phobos is so close and small and locked to the planet that it will one day get drawn in too close – past what is called The Roche limit – and it will begin to either break up, or crash into the planet!

Now, being a rather destructively minded sort, I hope for the planetary collision, but the most likely result will be the break up of the moon, and a ring around Mars… which should be fairly pretty. So if you’re around in 11 million years, you can enjoy that.

So there you go… more information than you could ever want about two orbital bodies that you’ve never bothered to worry about before. Which brings up the question; WHO CARES?

Well, you should – that’s who. Studying these moons and those like them can give us amazing insights into how planetary bodies are formed, which leads to notions of how the solar system was formed, and how other systems might be formed. It teaches us how baby-solar systems we observe might wind up forming in the future or present so we can plan missions there… and it also lets up get a glimpse at what might have been, and what could still happen in the future of out planet and others.


So respect planetary sciences, and don’t let me catch you not doing a science ever again.

Stay well.


6 thoughts on “Panic, Fear, and Planetary Science…

  1. pythoneer says:

    Nice one!

    Did my PhD on Phobos. Well, not actually *on* Phobos, obviously – about Phobos, I should say. It was many moons ago, though (excuse the pun 🙂

  2. Grace says:

    Are Martian werewolves bound by the same rules as the Earthling variety?

  3. RandomNerd says:

    “Phobos” may mean “fear” or “panic” in English, but it appears that you can only use “phobos” as a noun, not a verb. I DEMAND CLARIFICATION.

    • Phobos means fear, Deimos is panic. Though what the ancient Greek for the verb of fear is – I’ve no idea. Do a philology!

      • RandomNerd says:

        Haha, I always do mistakes when I am trying to correct someone… anyway, I did a Google Translate and found that panic can mean πανικοβάλλω (look, it’s Pi :D) or αλαφιάζω.

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