Mars' Moon Phobos is doomed

Tidewater

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I guess astronomers need to make headlines every now and then.
I read this. Interesting story. Phobos orbits Mars every 7.5 hours. It is getting closer to Mars (2 meters every century).
Then, buried in the article, I see Phobos has only 30-50 millions years left. Good thing I got to see pictures before it was gone.

On a related note, there is a crater named Stickney, which, in relation to the diameter of the moon, is enormous.

There are lighter-colored rays emanating from the crater, which astronomers thought was crater ejections. Now, they see that these do not emanate directly from the crater, and think that these are tidal stretch marks. Phobos appears to be a "pile of rubble" loosely held together, and covered with a powdery regolith (had to look that one up). I am surprised the Stickney impact did not blow Phobos apart.
Anyway, as it gets closer to Mars, the strength of gravity on the face closer to Mars will exceed that on the outer side so much, that Mars' gravity will pull the moon apart.
Found the story interesting and thought I would share.
 
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TIDE-HSV

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I guess astronomers need to make headlines every now and then.
I read this. Interesting story. Phobos orbits Mars every 7.5 hours. It is getting closer to Mars (2 meters every century).
Then, buried in the article, I see Phobos has only 30-50 millions years left. Good thing I got to see pictures before it was gone.

On a related note, there is a crater named Stickney, which, in relation to the diameter of the moon, is enormous.

There are lighter-colored rays emanating from the crater, which astronomers thought was crater ejections. Now, they see that these do not emanate directly from the crater, and think that these are tidal stretch marks. Mars appears to be a "pile of rubble" loosely held together, and covered with a powdery regolith (had to look that one up). I am surprised the Stickney impact did not blow Phobos apart.
Anyway, as it gets closer to Mars, the strength of gravity on the face closer to Mars will exceed that on the outer side so much, that Mars' gravity will pull the moon apart.
Found the story interesting and thought I would share.
Did you really mean Mars was a "pile of rubble," or that Phobos was?
 

Tidewater

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Did you really mean Mars was a "pile of rubble," or that Phobos was?
I think what they mean was that, being on the edge of the asteroid belt, Phobos assembled itself from rocks that that banged into each other. It is a pile of rocks, held together by their own weak gravity, and covered by a layer of talcum powder. Frankly, if true, I am surprised the Stickney impact did not knock all that loose again. The size of that crater (9 km in diameter) compared to the size of the moon itself (22 km in diameter, average), indicates to me that whatever made Stickney was relatively big (or maybe travelling pretty fast).

And yes, Mars does have a a bit of a run-down appearance. Whoever owns it has let the place go to pot.
 
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TIDE-HSV

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I think what they mean was that, being on the edge of the asteroid belt, Phobos assembled itself from rocks that that banged into each other. It is a pile of rocks, held together by their own weak gravity, and covered by a layer of talcum powder. Frankly, if true, I am surprised the Stickney impact did not knock all that loose again. The size of that crater (9 km in diameter) compared to the size of the moon itself (22 km in diameter, average), indicates to me that whatever made Stickney was relatively big (or maybe travelling pretty fast).

And yes, Mars does have a a bit of a run-down appearance. Whoever owns it has let the place go to pot.
Thanks. This is what you said: "Mars appears to be a "pile of rubble" loosely held together, and covered with a powdery regolith (had to look that one up)." I was pretty sure you meant Phobos. Phobos is so tiny, it appears to be right on the very edge to have enough mass/gravity to pull itself into a sphere...
 

Tidewater

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Thanks. This is what you said: "Mars appears to be a "pile of rubble" loosely held together, and covered with a powdery regolith (had to look that one up)." I was pretty sure you meant Phobos. Phobos is so tiny, it appears to be right on the very edge to have enough mass/gravity to pull itself into a sphere...
Oops, my bad. I did mean Phobos. Thanks for the correction.

Today, I found a video of a flight around Phobos.
Cool video.
What struck me was how oblong Phobos is.
 

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Tangentially, Larry Niven wrote a short story, "Neutron Star", that involved the catastrophic potential of tidal forces. A good read, particularly if you're a fan of hard science fiction.
 

Tidewater

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I have to confess to being an astronomy geek. (The only C grade I ever earned in college was in astronomy at UA). In the late 1970s, I eagerly read and clipped the newspaper reports from the Viking Mars landers. I remember watching the Apollo missions, but for some reason, Viking interested me a lot more.
Now, we having rovers driving around Mars. (well, one rover, anyway).
 

crimson fan man

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Tangentially, Larry Niven wrote a short story, "Neutron Star", that involved the catastrophic potential of tidal forces. A good read, particularly if you're a fan of hard science fiction.
I started enjoying reading science fiction back when I was a young teenager. The ones I enjoyed the most was the ones that put real science behind the story. Have read several Larry Niven books. He has been around for awhile.
 
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AUDub

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Give me ambiguity or give me something else.
I have to confess to being an astronomy geek. (The only C grade I ever earned in college was in astronomy at UA). In the late 1970s, I eagerly read and clipped the newspaper reports from the Viking Mars landers. I remember watching the Apollo missions, but for some reason, Viking interested me a lot more.
Now, we having rovers driving around Mars. (well, one rover, anyway).
Likewise. Been a hobbyist since high school.

It was nice when we lived out in the middle of nowhere. Perfect for the telescope. Hasn't been the same since we moved back into town.

ETA: Cracked had a great article on astronomy yesterday. Can't link because of profanity. Google "Six Things About Space You're Picturing Almost Exactly Wrong"
 
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Tidewater

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Likewise. Been a hobbyist since high school.

It was nice when we lived out in the middle of nowhere. Perfect for the telescope. Hasn't been the same since we moved back into town.

ETA: Cracked had a great article on astronomy yesterday. Can't link because of profanity. Google "Six Things About Space You're Picturing Almost Exactly Wrong"
Good video.

The thing I like about astronomy is that it is truly a passive science. Scientists in that field do not get to interact with the subject (at least not much). They only get to observe it, so they have to be very creative in how they observe things.
And they are creative about it.
 

crimsonaudio

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ETA: Cracked had a great article on astronomy yesterday. Can't link because of profanity. Google "Six Things About Space You're Picturing Almost Exactly Wrong"
Fun read - as I'm a NASA geek, little was surprising.

The last part reminded me of this animated gif of our solar system hurtling through the universe that I saw some time ago:

 

Tidewater

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I would have thought that the ecliptic would be closer in alignment to the galactic equator. I was wrong.
Since we are showing interesting diagrams:


The Sun executes oscillations around its mean orbit in the Galaxy, periodically crossing the Galactic plane. borrowed illustration (not to scale!) from to show this oscillatory motion. As the Sun is currently above the plane and moving upwards, and each cycle takes about 70 million years with an amplitude of 100pc (Matese et al. 1995), it will be roughly 30 million years before we cross the plane again.


Love the topic by the way. Who started this one?
 

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