The near coincidence of the perihelion (the EarthÂs closest approach to the Sun) and the winter solstice reminds me of some recent conversations with one of my conservative relatives who listens to talk radio. We disagree on whether global warming is human caused or whether it is simply the result of natural climate cycles. To be clear, I am no global warming apologist. The human planetary chemical experiment of increasing CO2 levels 30% over a century and a half is the most likely cause IMHO, and the appropriate precautionary principle response would be a massive and expensive conversion to renewable energy and sustainable technology. But, some would say that global warming is caused by changes in the Earth's relationship to the Sun, invoking a form of the Milankovitch cycle. Thus, there is nothing that requires a response, since the change is Âall natural. << http://en.wikipedia.org/wiki/Milankovitch_cycles >> This was brought home to me today (and tomorrow) by the relative closeness of the Sun's perihelion to the winter solstice. In another book I am currently reading, the author states that the Sun's solar longitude moves by 1.7463 degrees every 100 years. So, about 5,200 years ago, perihelion would have coincided with spring (about 90 degs of solar longitude away from its current solar longitude), and about 10,000 years ago, at the end of the last ice age, perihelion would have coincided with summer solstice. The solar aphelion (the EarthÂs farthest passage from the Sun) would have coincided with the winter solstice. Again, although I believe in human chemical-based cause for global warming, the current position of the solar perihelion would seem to support the idea that global warming is a consequence, at least in part, of natural climate cycles. - Canopus56(Kurt) __________________________________________ Yahoo! DSL  Something to write home about. Just $16.99/mo. or less. dsl.yahoo.com
Kirt; Most interesting. I read somewhere, about two years ago, that the polar ice caps on Mars were receding due to higher temperatures on the planet. The suggestion was that if Mars was experiencing global warming, then global warming of the earth was in part, at least, to natural causes. Have you or anyone else heard or observed the Martian ice caps to see if they are indeed shrinking and if so, any ideas of what is happening? Thanks, Ed Lunt --- Canopus56 <canopus56@yahoo.com> wrote:
The near coincidence of the perihelion (the EarthÂs closest approach to the Sun) and the winter solstice reminds me of some recent conversations with one of my conservative relatives who listens to talk radio. We disagree on whether global warming is human caused or whether it is simply the result of natural climate cycles. To be clear, I am no global warming apologist. The human planetary chemical experiment of increasing CO2 levels 30% over a century and a half is the most likely cause IMHO, and the appropriate precautionary principle response would be a massive and expensive conversion to renewable energy and sustainable technology.
But, some would say that global warming is caused by changes in the Earth's relationship to the Sun, invoking a form of the Milankovitch cycle. Thus, there is nothing that requires a response, since the change is Âall natural. << http://en.wikipedia.org/wiki/Milankovitch_cycles >>
This was brought home to me today (and tomorrow) by the relative closeness of the Sun's perihelion to the winter solstice. In another book I am currently reading, the author states that the Sun's solar longitude moves by 1.7463 degrees every 100 years. So, about 5,200 years ago, perihelion would have coincided with spring (about 90 degs of solar longitude away from its current solar longitude), and about 10,000 years ago, at the end of the last ice age, perihelion would have coincided with summer solstice. The solar aphelion (the EarthÂs farthest passage from the Sun) would have coincided with the winter solstice.
Again, although I believe in human chemical-based cause for global warming, the current position of the solar perihelion would seem to support the idea that global warming is a consequence, at least in part, of natural climate cycles.
- Canopus56(Kurt)
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--- Edward Lunt <lunco@yahoo.com> wrote:
Kirt; Most interesting. I read somewhere, about two years ago, that the polar ice caps on Mars were receding due to higher temperatures on the planet. The suggestion was that if Mars was experiencing global warming, then global warming of the earth was in part, at least, to natural causes. Have you or anyone else heard or observed the Martian ice caps to see if they are indeed shrinking and if so, any ideas of what is happening? Thanks, Ed Lunt
Ed, Here's a recent article mentioning Martian "Milankovitch cycles" and the Martian polar ice caps. The relevant para is lower down in the section marked "Recent water." Bruce M. Jakosky and Michael T. Mellon. Water on Mars. Physics Today Online. (Online article) http://www.physicstoday.org/vol-57/iss-4/p71.html Unlike Earth, Mars lacks a large moon. This allows a greater range of motion for the obliquity of the Martian ecliptic. The range of motion for the obliquity of the Martian ecliptic is 10 deg to 40 deg as opposed to about 22 deg to 24.5 deg for Earth. In the article, the authors describe how this has alot of implications for the long-term distribution of subsurface and surface water-ice on Mars - that is water is transported from higher to lower latitudes and back again in response to changes in the obliquity of the Martian ecliptic. The authors describe several recently discovered features on Mars (e.g. - ice polygons at lower latitudes), the presence of which they attribute to the Martian "Milankovitch cycles" acting as a transport method. I'm not sure how that relates to any historical changes in the last, let's say, a couple of hundred years, in the size of the Martian ice caps. Are there historical and current photos of the Martian ice caps, lets say from the 1950s and today. Are the Martain ice caps shrinking? - Canopus56(Kurt) __________________________________________ Yahoo! DSL Â Something to write home about. Just $16.99/mo. or less. dsl.yahoo.com
Thanks Kirt. Maybe someone else has an old photo or two that they would share. Ed --- Canopus56 <canopus56@yahoo.com> wrote:
--- Edward Lunt <lunco@yahoo.com> wrote:
Kirt; Most interesting. I read somewhere, about two years ago, that the polar ice caps on Mars were receding due to higher temperatures on the planet. The suggestion was that if Mars was experiencing global warming, then global warming of the earth was in part, at least, to natural causes. Have you or anyone else heard or observed the Martian ice caps to see if they are indeed shrinking and if so, any ideas of what is happening? Thanks, Ed Lunt
Ed,
Here's a recent article mentioning Martian "Milankovitch cycles" and the Martian polar ice caps. The relevant para is lower down in the section marked "Recent water."
Bruce M. Jakosky and Michael T. Mellon. Water on Mars. Physics Today Online. (Online article) http://www.physicstoday.org/vol-57/iss-4/p71.html
Unlike Earth, Mars lacks a large moon. This allows a greater range of motion for the obliquity of the Martian ecliptic. The range of motion for the obliquity of the Martian ecliptic is 10 deg to 40 deg as opposed to about 22 deg to 24.5 deg for Earth.
In the article, the authors describe how this has alot of implications for the long-term distribution of subsurface and surface water-ice on Mars - that is water is transported from higher to lower latitudes and back again in response to changes in the obliquity of the Martian ecliptic.
The authors describe several recently discovered features on Mars (e.g. - ice polygons at lower latitudes), the presence of which they attribute to the Martian "Milankovitch cycles" acting as a transport method.
I'm not sure how that relates to any historical changes in the last, let's say, a couple of hundred years, in the size of the Martian ice caps.
Are there historical and current photos of the Martian ice caps, lets say from the 1950s and today. Are the Martain ice caps shrinking?
- Canopus56(Kurt)
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See the following about global warming on Mars: http://www.space.com/scienceastronomy/mars_ice-age_031208.html And: http://www.newscientist.com/article.ns?id=dn1660 Mars may indeed be undergoing global warming and the cause in part may be the Sun. See the book "The Role of the Sun in Climate Change" by Hughes Scientist Douglas Hoyt and NASA scientist Kenneth Schatten. The Sun is a variable star, thankfully not too variable. Clear Skies Don -----Original Message----- From: utah-astronomy-bounces+djcolton=piol.com@mailman.xmission.com [mailto:utah-astronomy-bounces+djcolton=piol.com@mailman.xmission.com] On Behalf Of Edward Lunt Sent: Wednesday, January 04, 2006 12:29 PM To: Utah Astronomy Subject: Re: [Utah-astronomy] Today's perihelion and global warming Thanks Kirt. Maybe someone else has an old photo or two that they would share. Ed --- Canopus56 <canopus56@yahoo.com> wrote:
--- Edward Lunt <lunco@yahoo.com> wrote:
Kirt; Most interesting. I read somewhere, about two years ago, that the polar ice caps on Mars were receding due to higher temperatures on the planet. The suggestion was that if Mars was experiencing global warming, then global warming of the earth was in part, at least, to natural causes. Have you or anyone else heard or observed the Martian ice caps to see if they are indeed shrinking and if so, any ideas of what is happening? Thanks, Ed Lunt
Ed,
Here's a recent article mentioning Martian "Milankovitch cycles" and the Martian polar ice caps. The relevant para is lower down in the section marked "Recent water."
Bruce M. Jakosky and Michael T. Mellon. Water on Mars. Physics Today Online. (Online article) http://www.physicstoday.org/vol-57/iss-4/p71.html
Unlike Earth, Mars lacks a large moon. This allows a greater range of motion for the obliquity of the Martian ecliptic. The range of motion for the obliquity of the Martian ecliptic is 10 deg to 40 deg as opposed to about 22 deg to 24.5 deg for Earth.
In the article, the authors describe how this has alot of implications for the long-term distribution of subsurface and surface water-ice on Mars - that is water is transported from higher to lower latitudes and back again in response to changes in the obliquity of the Martian ecliptic.
The authors describe several recently discovered features on Mars (e.g. - ice polygons at lower latitudes), the presence of which they attribute to the Martian "Milankovitch cycles" acting as a transport method.
I'm not sure how that relates to any historical changes in the last, let's say, a couple of hundred years, in the size of the Martian ice caps.
Are there historical and current photos of the Martian ice caps, lets say from the 1950s and today. Are the Martain ice caps shrinking?
- Canopus56(Kurt)
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--- "Don J. Colton" <djcolton@piol.com> wrote:
The Sun is a variable star, thankfully not too variable.
I understand there is a similar effect tied to solar insolation on the redness of the Great Red Spot (GRS). The redness of the varies on a 30 year cycle tied to the solar cycle, but over the centuries, let's say since Cassini, Haley and Herschel, its redness has declined. I've forgotten the mechanism of action. I seem to recall that the redness of the GRS was a chemical smog phenomena - the more instense sunlight breaks up the red light chemical that accumulates in the upper Jovian atmosphere. Or was it the over way around? Maybe it's time to rename the GRS to the "Great Salmon-Colored Spot". - Canopus56(Kurt) __________________________________________ Yahoo! DSL Â Something to write home about. Just $16.99/mo. or less. dsl.yahoo.com
Quoting Canopus56 <canopus56@yahoo.com>:
I understand there is a similar effect tied to solar insolation on the redness of the Great Red Spot (GRS). The redness of the varies on a 30 year cycle tied to the solar cycle, but over the centuries, let's say since Cassini, Haley and Herschel, its redness has declined. I've forgotten the mechanism of action.
It's called "fading". I had a red Toyota LandCruiser that faded because I left it in the sun. Wax seemed to prolong the fading, but, it still faded none-the-less. I don't know, do you think a red car is more prone to fade than say, a white one? ;)
the more instense sunlight breaks up the red light chemical that accumulates in the upper Jovian atmosphere...
Probably the same thing...
participants (4)
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Canopus56 -
diveboss＠xmission.com -
Don J. Colton -
Edward Lunt