meet old Mars

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Re: meet old Mars

by rob42 » Sat Feb 02, 2013 1:21 pm

falkor wrote:nice one Rob
Liquid water is essential for life as we know it, but it's a rare commodity in our solar system.

The so-called Goldilocks zone is a narrow region between the orbits of Venus and Mars where the temperature is 'just right' for water to remain liquid - not too hot and not too cold.

On a planet orbiting closer to the Sun water boils away; on a planet orbiting further away water turns to ice.

Our blue planet sits perfectly within this 'just right' zone. Mars sits on the outskirts of this zone, farthest away from the Sun. It gets very cold: minus 60 degrees Celsius on an average day.

These low temperatures, along with Mars' thin atmosphere, make it impossible for liquid water to exist on Mars' surface.
the above from BBC's science site :P so you have it correct
Thanks, but not so fast, as I believe that the BBC is talking about the here-and-now? The thing I can't get my head around is how the planet (Mars) seems to have been warm enough, a billion years ago, to sustain liquid water long enough to create the signs that are being interpreted in that way....

such as... http://www.slate.com/blogs/bad_astronom ... _mars.html

and

http://www.slate.com/blogs/bad_astronom ... there.html

... (to name but two), let alone sustain any form of vegetation and earth-like life-forms.

Maybe what is being suggested is that a billion years ago+, the orbits of the planet was such that all were closer to our Sun than they are today?

More research needed on my part, I think... :geek:

Re: meet old Mars

by falkor » Mon Jan 28, 2013 11:15 pm

nice one Rob
Liquid water is essential for life as we know it, but it's a rare commodity in our solar system.

The so-called Goldilocks zone is a narrow region between the orbits of Venus and Mars where the temperature is 'just right' for water to remain liquid - not too hot and not too cold.

On a planet orbiting closer to the Sun water boils away; on a planet orbiting further away water turns to ice.

Our blue planet sits perfectly within this 'just right' zone. Mars sits on the outskirts of this zone, farthest away from the Sun. It gets very cold: minus 60 degrees Celsius on an average day.

These low temperatures, along with Mars' thin atmosphere, make it impossible for liquid water to exist on Mars' surface.
the above from BBC's science site :P so you have it correct

Re: meet old Mars

by rob42 » Fri Jan 11, 2013 10:36 pm

I still don't understand how you can have liquid water on a planet where the temperature would be below zero degs C for much of the time, even if Mars did once have some sort of an atmosphere.

The distance between the Sun and the Earth is about 93 million miles.

Mars has an elliptical orbit and as such is somewhat more complex: At its closest, Mars is about 128.5 million miles away and when it's at its farthest, it is about 155 million miles away from the Sun. Is that not a little far away to have sustainable liquid water? I'm sure that on the hottest day of the hottest year you may get liquid water, but the rest of the time (which is most of the time), I don't see how it could be. :?

Re: meet old Mars

by falkor » Mon Jan 07, 2013 10:34 pm

I don't think the Sun is changing size (yet) although it will do towards the end of it's life :o
Evidence gathered by rovers and satellites such as Curiosity and the Mars Reconnaissance Orbiter suggests that, billions of years ago, the Red Planet was once covered in lakes and oceans, and that it had a thicker atmosphere. It may have even supported life. Any liquid water and life is now gone, but once upon a time, Mars might’ve looked a lot like Earth.
if the Red Planet was once covered in lakes and oceans then surely it must have been pretty similar to Earth

from what I recall, the slow disappation of it's atmosphere lead to it's barren like state :conF:

It is amazing to think that Terraformers could "return that atmosphere" within 100 years

======================== new article
http://www.bbc.co.uk/science/0/20915340

Image
look how small Mars is!!

Re: meet old Mars

by rob42 » Mon Jan 07, 2013 9:15 pm

It's very pretty.

I'm trying to get my head around the fact that all this implies that Mars must have been, at one time, in a similar so called "Goldilocks" zone to the Earth? But as Mars is further out from the Sun and the Sun is getting bigger as it ages, it must have been, billions of years ago, smaller? If it was smaller, then Mars would have received even less energy from the Sun than it does now. I don't see how that would make it more "Earth-like".

I know that my knowledge of Astronomy is VERY limited, so if someone could explain this, or point me to a good site where it is explained? :?

Re: meet old Mars

by mj12cz » Sun Jan 06, 2013 7:16 pm

WOW thats pretty cool!

meet old Mars

by falkor » Fri Jan 04, 2013 10:10 pm

Image
Image
What Mars might’ve looked like, billions of years ago
By Sebastian Anthony on January 4, 2013 at 8:06 am
A long time ago, Mars wasn’t the barren lump of rock and dust that it is today. Evidence gathered by rovers and satellites such as Curiosity and the Mars Reconnaissance Orbiter suggests that, billions of years ago, the Red Planet was once covered in lakes and oceans, and that it had a thicker atmosphere. It may have even supported life. Any liquid water and life is now gone, but once upon a time, Mars might’ve looked a lot like Earth.

In the beautiful images above and below, Kevin Gill has attempted to recreate what Mars may have looked like billions of years ago. The images are somewhere between an artist’s concept and a scientific approximation. Gill used real elevation data to plot out Mars’ oceans, mountains, valleys, and other geological features — but then he used his own judgment to paint in the deserts, forests, and so on, using textures from NASA’s Blue Marble imagery. “There is no scientific reasoning behind how I painted it; I tried to envision how the land would appear given certain features or the effects of likely atmospheric climate. For example, I didn’t see much green taking hold within the area of Olympus Mons and the surrounding volcanoes, both due to the volcanic activity and the proximity to the equator,” Gill says.

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