The gullies on Mars are caused by a variety of factors, linked to both water and carbon dioxide
In doing a detailed global analysis of all the known gullies on Mars, scientists now believe the gullies are formed by a variety of factors, linked to both water and carbon dioxide as well as the planet’s radically changing rotational tilt — varying from 11 to 60 degrees — over time.
Noblet’s paper articulates a “hierarchy of factors” that describes where gullies occur, with well-supported explanations as to why they form in one place and not another. None of the explanations in this paper are new. What’s new is how Noblet and coworkers reconcile apparent contradictions and inconsistencies among other researchers’ explanations of gully formation, explaining why an explanation that works for one spot on Mars doesn’t work in another.
The map above, from their paper, shows the global distribution of the gullies, which appear to favor the same mid-latitudes where the planet’s glaciers are mostly found. The data from many different studies suggests that when the planet’s rotational tilt was high, these mid-latitudes regions were warmer, and the near-surface ice there would sublimate away to get redeposited at the poles. When this happened the sublimation would cause the pole-facing gullies to form.
The paper also suggests that any gullies changing today are likely the result of the sublimation of carbon dioxide, not water.
There is a lot more at the article at the link, which is an excellent summation of this research.
On Christmas Eve 1968 three Americans became the first humans to visit another world. What they did to celebrate was unexpected and profound, and will be remembered throughout all human history. Genesis: the Story of Apollo 8, Robert Zimmerman's classic history of humanity's first journey to another world, tells that story, and it is now available as both an ebook and an audiobook, both with a foreword by Valerie Anders and a new introduction by Robert Zimmerman.
The print edition can be purchased at Amazon. from any other book seller, or direct from my ebook publisher, ebookit.
The ebook is available everywhere for $5.99 (before discount) at amazon, or direct from my ebook publisher, ebookit. If you buy it from ebookit you don't support the big tech companies and the author gets a bigger cut much sooner.
The audiobook is also available at all these vendors, and is also free with a 30-day trial membership to Audible.
"Not simply about one mission, [Genesis] is also the history of America's quest for the moon... Zimmerman has done a masterful job of tying disparate events together into a solid account of one of America's greatest human triumphs."--San Antonio Express-News
In doing a detailed global analysis of all the known gullies on Mars, scientists now believe the gullies are formed by a variety of factors, linked to both water and carbon dioxide as well as the planet’s radically changing rotational tilt — varying from 11 to 60 degrees — over time.
Noblet’s paper articulates a “hierarchy of factors” that describes where gullies occur, with well-supported explanations as to why they form in one place and not another. None of the explanations in this paper are new. What’s new is how Noblet and coworkers reconcile apparent contradictions and inconsistencies among other researchers’ explanations of gully formation, explaining why an explanation that works for one spot on Mars doesn’t work in another.
The map above, from their paper, shows the global distribution of the gullies, which appear to favor the same mid-latitudes where the planet’s glaciers are mostly found. The data from many different studies suggests that when the planet’s rotational tilt was high, these mid-latitudes regions were warmer, and the near-surface ice there would sublimate away to get redeposited at the poles. When this happened the sublimation would cause the pole-facing gullies to form.
The paper also suggests that any gullies changing today are likely the result of the sublimation of carbon dioxide, not water.
There is a lot more at the article at the link, which is an excellent summation of this research.
On Christmas Eve 1968 three Americans became the first humans to visit another world. What they did to celebrate was unexpected and profound, and will be remembered throughout all human history. Genesis: the Story of Apollo 8, Robert Zimmerman's classic history of humanity's first journey to another world, tells that story, and it is now available as both an ebook and an audiobook, both with a foreword by Valerie Anders and a new introduction by Robert Zimmerman.
The print edition can be purchased at Amazon. from any other book seller, or direct from my ebook publisher, ebookit. The ebook is available everywhere for $5.99 (before discount) at amazon, or direct from my ebook publisher, ebookit. If you buy it from ebookit you don't support the big tech companies and the author gets a bigger cut much sooner.
The audiobook is also available at all these vendors, and is also free with a 30-day trial membership to Audible.
"Not simply about one mission, [Genesis] is also the history of America's quest for the moon... Zimmerman has done a masterful job of tying disparate events together into a solid account of one of America's greatest human triumphs."--San Antonio Express-News
Readers: the rules for commenting!
No registration is required. I welcome all opinions, even those that strongly criticize my commentary.
However, name-calling and obscenities will not be tolerated. First time offenders who are new to the site will be warned. Second time offenders or first time offenders who have been here awhile will be suspended for a week. After that, I will ban you. Period.
Note also that first time commenters as well as any comment with more than one link will be placed in moderation for my approval. Be patient, I will get to it.