NASA reports recent running water on Mars.

[Soapy Sam]

http://space.newscientist.com/data/images/ns/cms/dn10740/dn10740-1_627.jpg

While I see a difference in these two photographs, I can't honestly say it looks like water flow to me.
However if we learned one thing from the "Moon hoax" pictures , it is that terrestrial bias in photo interpretation can be counter productive on other worlds.

What do others think? Water? Avalanche?Dry ice? Other?

ETA. Should have known. Beaten to it:-
http://forums.randi.org/showthread.php?t=70032

[andyandy]

sand?

a giant white snake?

[andyandy]

The appearance of gullies, revealed in orbital images from a Nasa probe, suggests that water could have flowed on the surface in the last few years.

But some scientists think these fresh gullies could also have been cut by liquid carbon dioxide (CO2). http://news.bbc.co.uk/1/hi/sci/tech/6214834.stm

liquid CO_2 perhaps.....

[drkitten]

http://news.bbc.co.uk/1/hi/sci/tech/6214834.stm

liquid CO_2 perhaps.....

No effin' way it's liquid carbon dioxide. The BBC researchers are on crack., unless I'm woefully misremembering my secondary school chemistry.

Dry ice sublimes -- evaporates directly from a solid to a gas -- at pressures less than about 5atm. The chance of carbon dioxide becoming or staying liquid at Martian atmospheric pressures makes "monkeys flying out of my butt" look like a good safe bet.

[andyandy]

No effin' way it's liquid carbon dioxide. The BBC researchers are on crack., unless I'm woefully misremembering my secondary school chemistry.

.

you remember that from secondary school chemistry? All i took away from my lessons is that magnesium ribbon glows when you put it in a bunsen burner :D

[drkitten]

you remember that from secondary school chemistry?

We used to make dry ice bombs to scare the students in the classroom next door.

We had to use dry ice because the teacher wouldn't let us at the magnesium....

.... which is probably why the school is still standing.

[Paul C. Anagnostopoulos]

I'm not sure those tracks are liquid water. I think they are residue left behind by running water, supposedly.

~~ Paul

[Foster Zygote]

Well whatever it is, it's damned intriguing. I can't wait to hear more.

[trvlr2]

Where would the sun's light have been on the two different days? Artifact of shadow?

[Molinaro]

A bright shiny shadow?

[Hamish]

No effin' way it's liquid carbon dioxide. The BBC researchers are on crack., unless I'm woefully misremembering my secondary school chemistry.

Dry ice sublimes -- evaporates directly from a solid to a gas -- at pressures less than about 5atm. The chance of carbon dioxide becoming or staying liquid at Martian atmospheric pressures makes "monkeys flying out of my butt" look like a good safe bet.

And to back you up here's some carbon dioxide facts, including a phase diagram:
http://scifun.chem.wisc.edu/chemweek/CO2/CO2.html. No liquid carbon dioxed below 5.11 atm. Not likely on Mars.

I'd be interested to know where that "liquid CO2" idea came from. It certainly doesn't appear in the NASA press release (at least as far as i can tell).

[Level]

Phil's got some comments up too: http://www.badastronomy.com/bablog/2006/12/06/liquid-water-on-mars/

[Hamish]

Aha! I've found it: http://unisci.com/stories/20012/0402013.htm

The idea seems to be that the CO2 is trapped in the rock where the pressure of the rock above is enough for it to reach the liquid phase. As it escapes it forms CO2 snow and gas which combine with rock dust to form a slurry which flows down the gully.

Sounds a bit more plausible when you put it like that.

[trvlr2]

Molinaro- Nah, Bright & shiny means it's reflecting light well.
What I meant to say was artifact of 'light & shadow'. Without light, there IS no shadow. Put the light at a different angle, different features may appear. (faces on Mars)Sorry, I didn't explain it better. But, they keep hiding my purple crayon, the special posting one.

[Molinaro]

trvlr2, I understood what you meant, I just that comment of mine would be an amusing way of spurring you on to provide a bit clearer explanation. :)

Since these photos where taken for the exact reason of looking for changes in landscape in areas where flows are suspected I would expect NASA to have taken them from as close as is possible to the same sun-mars-satelite geometry as the 1st images.

[Notrump]

Once again the public is enthused by news that might fulfill some of their hopes and wishes with little skepticism. Is that good science?

A Reuters article on the subject inserted the following paragraph:

The scientists conceded the images were only circumstantial evidence not proof. They cited a possible alternative explanation that those features were caused by the movement of dry dust down a slope.

I recall similar hoopla a decade ago when NASA had President Clinton announce that an Antarctic meteorite contained small spheres that were likely fossilized Martian bacteria. That was later debunked.

NASA officials know that much of their funding is dependent on the public believing they are searching for life, or at least water. They tend to make announcements that may be positive to this theme well before sufficient examination has been done. Actually, I'm all for such schemes that cause taxpayers to become willing to pay for the scientific exploration of the solar system. I only object when a significant portion of the funding is diverted to manned missions.

[UnrepentantSinner]

I heard Hoagland on Coast to Coast last night. His reaction was typical of what you'd expect - this is just another incremental dribble of new information leading to the revelation of civilization on Mars by the Masonic/Egyptian/NASA conspiracy. It's been forever since I've checked out his website, but I'm sure he's got the new photos all marked up showing the "evidence." He also mentioned the resolution of the MRO will allow photos showing individual bricks in the buildings at Cydonia.