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Arsia Mons Cloud Streak

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#1 HentySky

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Posted 12 October 2018 - 01:34 AM

Hello Folks, 

 

I capture the attached image of Mars on September 25.  When I processed the first file a few days later a dark streak running to the west of Arsia Mons caught my eye.  I thought it was a processing artefact at first but when I processed the remaining files they all had the same feature.  I captured Mars for a period of about an hour.

 

Comparing it to images of the same location I photographed in the previous month the feature did not appear on the earlier images.  I did a search on the internet and could not find any images of Arsia Mons with this feature.  To save embarrassment to my self I decided not to post the image.  A week ago I noticed someone on ALPO Japan also imaged the same feature.  The Mars Express Mission team have also caught this feature on the VMC camera of their ESA Mars Orbiter space craft and are investigating it.

 

I don't know what it is but is most likely some sort of cloud.  I have included the B channel in the attachment over processed which shows a cloud over Arsia Mons.  I have also included the final image I took that night (UT 14:17) and the feature was still there.

 

I think there is enough evidence now that I am not so embarrassed!  Just putting it out there in case someone is interested.

 

Cheers Brett

Attached Thumbnails

  • Arsia Mons 1.jpg

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#2 Kokatha man

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Posted 12 October 2018 - 01:52 AM

Interesting Brett - a quick look tells me I can see something in J. Jovani's image from 4th October...back to R. Iwamasa's image from 24/9...probably others - which image that you mention from there (ALPO-Japan) are you referencing here..?



#3 Kokatha man

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Posted 12 October 2018 - 01:59 AM

ps: the dark "line" is evident in our images here from the 21st September: https://www.cloudyni...s/#entry8882115 in the later capture (rgb & r) with the red example I'll post here if you'll forgive me. (posted lower down in our own thread I've linked to)

 

No real idea of its identity tbh...

 

m2018-09-21_11-47_r_dpm.png

 

 


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#4 HentySky

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Posted 12 October 2018 - 03:51 AM

Darryl, well this is embarrassing now, I can't find the post I saw on ALPO, but it was from Clyde Foster.  Anyway attached is the image from the ESA spacecraft of the Arsia Mons cloud which pretty much matches our images (compliments to Michael Khan).

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  • ESA Image.jpg

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#5 happylimpet

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Posted 12 October 2018 - 03:54 AM

Shadow of a tall orographic cloud by the looks of things. Wonderful capture, well done.


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#6 CPellier

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Posted 13 October 2018 - 03:26 AM

Superb. The fact that the Arsia cloud is visible again shows could be considered as final point to the storm.

The streak/shadow is very interesting too!


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#7 Jeff B1

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Posted 13 October 2018 - 02:37 PM

Hum, that is a nice shadow alright, Brett. A nice high orographic cloud, very well defined in blue light as well.  I have seen shadows from dust clouds and a few from orographic clouds, but, of course, never that sharp and as well defined. Very nice image for sure. Where are you imaging from?  Your seeing  must be very good, huh?

 

Jeff


Edited by Jeff B1, 13 October 2018 - 02:42 PM.


#8 HentySky

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Posted 13 October 2018 - 09:14 PM

Thanks for your comments everyone.

 

I have found a paper written by Mike Malaska on this Arsia Mons phenomenon which was quite interesting.

 

Jeff, my observatory is in the south west corner of Australia.  I have been very fortunate this Mars season to get some excellent seeing (mostly happens when we get gentle winds off the Indian ocean).  With summer approaching that will start to disappear unfortunately.


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#9 Gabor Kiss

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Posted 14 October 2018 - 05:52 AM

That's very interesting indeed. Thanks for sharing!



#10 Jeff B1

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Posted 14 October 2018 - 07:32 AM

Thanks for your comments everyone.

 

I have found a paper written by Mike Malaska on this Arsia Mons phenomenon which was quite interesting.

 

Jeff, my observatory is in the south west corner of Australia.  I have been very fortunate this Mars season to get some excellent seeing (mostly happens when we get gentle winds off the Indian ocean).  With summer approaching that will start to disappear unfortunately.

Hope you keep up interest in Mars and imaging it. Thanks.



#11 GeorgeInDallas

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Posted 26 October 2018 - 04:39 PM

Amazing images!  

 

In 2003 I and several other imagers (including Thierry Legault) caught images of a dark spot over Arisa Mons. The image and further explanation are posted on my Mars web page (near the bottom of the page).

 

https://georgeastro....y.com/mars.html

 

I sent an e-mail to the Mars Global Surveyor Imaging Team and their speculation was that it was a shadow caused by an cloud feature above Arisa Mons. I later ran across images from the Mars Global surveyor that show close ups of a towering (nearly 20 miles high) dust cloud that often appears over Arisa Mons. Here is a link to the Mars Orbital Camera images from 2001, 2003 and 2005 that show the feature. There is an explanation of how the cloud is formed.

 

http://www.msss.com/...20/arsia_cloud/

 

George



#12 Kokatha man

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Posted 26 October 2018 - 06:13 PM

Excellent post George! waytogo.gif

 

The only confusing aspect to me in the article is where it states: 

 

Quote: <"In some regions, the repeated event may be a dust storm that appears every year, like clockwork, in such a way that we can only wish the weather were so predictable on Earth.

One of the repeated weather phenomena occurs each year near the start of southern winter over the martian volcano, Arsia Mons.">

 

By the ready-reckoner tables I consult Winter solstice for the Northern Hemisphere occurred on October 16th 2018 - the would appear "amazingly" early for a reference point to "near the start of southern winter" - or am I off-beam this morning..? shocked.gif

 

It is early for me to be on the pc, so perhaps I might need enlightening! lol.gif

 

Great image you captured back in 2003 btw George! waytogo.gif waytogo.gifwaytogo.gif  



#13 Jeff B1

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Posted 26 October 2018 - 06:23 PM

Amazing images!  

 

In 2003 I and several other imagers (including Thierry Legault) caught images of a dark spot over Arisa Mons. The image and further explanation are posted on my Mars web page (near the bottom of the page).

 

https://georgeastro....y.com/mars.html

 

I sent an e-mail to the Mars Global Surveyor Imaging Team and their speculation was that it was a shadow caused by an cloud feature above Arisa Mons. I later ran across images from the Mars Global surveyor that show close ups of a towering (nearly 20 miles high) dust cloud that often appears over Arisa Mons. Here is a link to the Mars Orbital Camera images from 2001, 2003 and 2005 that show the feature. There is an explanation of how the cloud is formed.

 

http://www.msss.com/...20/arsia_cloud/

 

George

I have a visual drawing  of that very same dusty water cloud over Arsia Mins on that date.  I think Parker imaged it as well and may look for his image. We would see blue clouds mixed with dust now and then, in  fact many times. 


Edited by Jeff B1, 26 October 2018 - 06:25 PM.


#14 Kokatha man

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Posted 26 October 2018 - 06:29 PM

Hmmm.....just doing some digging in my dazed early morning state & now come across an article by Dr. Tanya Harrison where the clouds are identified as  orographic clouds: https://twitter.com/...223756845961218 ...& my belief about what season it is on Mars seems vindicated! I haven't gone completely crackers - yet lol.gif

 

Another very recent article here: http://www.esa.int/O...n_curious_cloud

 

As I said above, we also caught this cloud on September 21st & I might revisit our data from that night out of increased curiosity now! wink.gif


Edited by Kokatha man, 26 October 2018 - 06:32 PM.


#15 Jeff B1

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Posted 26 October 2018 - 06:33 PM

Yes, Daryl, great article I read back then. Capen practically wrote the book on  those clouds and I filled in the charts and  math :)



#16 Kokatha man

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Posted 26 October 2018 - 06:53 PM

Hi Jeff - you're referring to the 2003 date in your post..?

 

Any chance of a web link to it..?

 

It seems to me the link George posted where they talk about spiral clouds over Arsia Mons must be something that occurs at a different time of the year if my head is clear there.....with the article stating "near the start of southern winter" - whereas those captured around September 21st this year were obviously from a different season on Mars (just after the Northern Summer solstice) & more in line with the latter links I posted above..... 

 

At any rate I have just been looking at our own images from that date (Sept. 21st) & to my surprise, even though we captured the long shadow at UT 11:46:32 as in my Post #3 here in Brett's thread, I have several captures up to 3/4 hour later for that night that I never processed!

 

I don't know whether the Sun angle might make the shadow less-emphasized but Arsia Mons should be more readily seen in later captures...

 

Guess what I'll be doing in my spare time today! lol.gif



#17 GeorgeInDallas

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Posted 26 October 2018 - 07:53 PM

Hi,

 

Darryl, Jeff,

 

I can not pretend to know anything about the statements made regarding the time of the Mars year of the dust cloud occurring. I only remember that the response that I got said that the dark spot MAY be related to a cloud formation over Arisa Mons. The connection between the dark spot that I imaged and the images of the spiral dust clouds over Arisa Mons is just my associating the unusual spiral dust cloud images with the reference to a cloud formation over Arisa Mons. No one from NASA or anywhere else told me that there was any relationship. It does seem reasonable that a 20 mile high spiral dust cloud over a 6 mile high volcano would produce a long shadow near the terminator. Maybe the conditions that produce the spiral dust cloud can occasionally occur at other times of the year, Similar to the way we can occasionally get a tornado in Texas in December when the peak tornado season is in the spring. 

 

George


Edited by GeorgeInDallas, 26 October 2018 - 08:04 PM.


#18 HentySky

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Posted 26 October 2018 - 08:27 PM

Great investigation work folks.  When I first took the image and checked the internet I couldn't find anything, I guess I didn't look very hard!

 

Darryl, very interesting articles you have links to.  I like the comment in one article and I quote "reaching such an impressive size that could make it visible even to telescopes on Earth".  Yep, they were right there.

 

Brett



#19 Kokatha man

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Posted 26 October 2018 - 10:02 PM

Hi George & Brett, & Jeff - without further investigation, I suppose it is possible that the "spiral cloud" phenomenon you referred/linked to is possibly just one instance of clouds creating long shadows around Arsia Mons - but for my money the 3 Global Surveyor images were all taken very shortly after the Autumnal Equinox in the Northern Hemisphere in 2001, 2003 & 2005 respectively.

 

Your (slightly later) image on August 29th 2003 was a few weeks before the Winter Solstice. (Northern Hemisphere)

 

I'll set these dates down here for anyone's consideration...& I haven't got back into re-reading Dr. Harrison's comments again except to note that in the 2nd link I posted in Post #14 above, the most current data, we can read the following:

 

<"Mars just experienced its northern hemisphere winter solstice on 16 October. In the months leading up to the solstice, most cloud activity disappears over big volcanoes like Arsia Mons; its summit is covered with clouds throughout the rest of the martian year.

However, a seasonally recurrent water ice cloud, like the one shown in this image, is known to form along the southwest flank of this volcano – it was previously observed by Mars Express and other missions in 2009, 2012 and 2015.">

 

George's link is to the September 2005 Global Surveyor images & the comments in that older article: <"One of the repeated weather phenomena occurs each year near the start of southern winter over the martian volcano, Arsia Mons. The volcano is located near 9°S, 121°W. Each year, just before southern winter begins, sunlight warms the air on the slopes of the volcano"> would suggest that the recent (September 2018) cloud & shadow are out of kilter with the season(s) in which these spiral formations develop!!!

 

However, if we suggest that the statements <"One of the repeated weather phenomena occurs each year near the start of southern winter over the martian volcano, Arsia Mons. The volcano is located near 9°S, 121°W. Each year, just before southern winter begins, sunlight warms the air on the slopes of the volcano"> should actually read "southern summer" or "northern winter " it would accord more with the latest events..!

 

To me this is the only possibility that makes any sense, ie, the 2005 Global Surveyor article got their North & South mixed up! lol.gif - that & the fact that the article George refers to is incorrect as far as the seasons are concerned if you look at the ready-reckoner here: http://www.planetary...s-calendar.html  

 

Don't shoot me if I'm wrong, but Pat agrees so we may both be quite crackers...but I'll shoulder the blame for convincing her of my view! rofl2.gif

 

Brett, I noticed that comment...you deserve full credit for picking this shadow up waytogo.gif waytogo.gif waytogo.gif ...I only became aware of it in our own images after you posted your own here: fortunately in some ways I must have been suffering from processing overload at the time so I only processed one of the images displaying it in our own data. (red filter, UT 11:47 & rgb UT 11:49)

 

I'll look again at the blue filter & have already processed 2 red filter captures ( 11:53 & 11:59) that also display the shadow.....hoping more still to come plus rgb's although as Mars rotates further in the later times the shadow shortens etc...but there might be the remote possibility of an enhanced animation focusing on this feature... fingerscrossed.gif 


Edited by Kokatha man, 26 October 2018 - 10:05 PM.


#20 HentySky

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Posted 26 October 2018 - 11:33 PM

Darryl, Jeff, George, on the night of the 25th of September I basically had my ASI290MM running continuously from UT 13.23 to UT 14.20, after which I decided to turn the camera off even though the seeing was near perfect.  At that point I had decided nothing much was happening on Mars and I had captured all there was to get, little did I know I should have kept the camera going for another hour or so.  I have enough data for 6 colour frames over that capture hour so I will attempt an animation when I get some time.  Good luck with yours Darryl.  Brett


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#21 Kokatha man

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Posted 27 October 2018 - 02:11 AM

Brett, I've been out & only processed the individual r-g-b channels centred around UT 12:02...plus the red filters 11:54 & 12:07...

 

As I suspected it does look like it is best catching the shadow from the clouds around Arsia Mons in the area slightly west of it when this region is nearest the F limb...Sun angle & shadow wise.

 

But I still have a few more avi's to process including an iR610 at 12:16 so I'll wait & see what eventuates. fingerscrossed.gif

 

My Post #19 is my usual long-winded way of saying that in the article from 2005 that George linked to, they almost certainly meant to say that "as Summer advances <"sunlight warms the air on the slopes of the volcano"> as per the latest links' commentaries' intimations.....it is hardly likely to heat the air in the approach to Winter in the Southern Hemisphere from ordinary logic... confused1.gif



#22 Jeff B1

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Posted 27 October 2018 - 06:33 AM

Hi Jeff - you're referring to the 2003 date in your post..?

 

Any chance of a web link to it..?

 

It seems to me the link George posted where they talk about spiral clouds over Arsia Mons must be something that occurs at a different time of the year if my head is clear there.....with the article stating "near the start of southern winter" - whereas those captured around September 21st this year were obviously from a different season on Mars (just after the Northern Summer solstice) & more in line with the latter links I posted above..... 

 

At any rate I have just been looking at our own images from that date (Sept. 21st) & to my surprise, even though we captured the long shadow at UT 11:46:32 as in my Post #3 here in Brett's thread, I have several captures up to 3/4 hour later for that night that I never processed!

 

I don't know whether the Sun angle might make the shadow less-emphasized but Arsia Mons should be more readily seen in later captures...

 

Guess what I'll be doing in my spare time today! lol.gif

Darryl, I’m afraid that in 2003 Chick Capen had been gone for 17 years (http://www.alpo-astr.../ChickCapen.pdf) and his work was extensive until 1986, so you’ll have to search the Net for info on him. He was a well known authority of Mars and a meteorologist to boot. What I contributed can be found here:  http://www.alpo-astr...h/Beishpap.pdf  Just saying.  Like anyone else our hay day was back in the day; some old Martians die, but most of us just fade away into the abyss :).



#23 kbev

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Posted 27 October 2018 - 08:46 AM

Happened to notice a NY Times article on this in my news feed yesterday, found a similar article on a site that has easier access and didn't try to over-sensationalize the phenomenon:

https://www.sciencea...loud-arsia-mons

 

Still a great capture for an amateur scope!



#24 Jeff B1

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Posted 27 October 2018 - 09:17 AM

With even the very good seeing here in Florida and a high quality 16” -- trying to see the fine details of a cloud streak and accompanying shadow is a feat.  I remember seeing an orographic cloud over Arsia Mons in June 2001, April 2003 and February 2005, as described on Malin's web site (MOC-1224).  Even those times in near perfect seeing detailing the streak and shadow is very hard to see, then draw. 

 

Shadows will be seen next to bright dust clouds, but at times the irradiation in our eyes will also produce such features, so one has to be aware of that.  Some of the clouds from Arsia, or Olympus Mons, can also contain some dust and they will be bright in both blue light as well as orange light.  Elysium Mons always has a cloud over or near it in certain seasons. Yeah, us older folks can have a film on the eye than causes blurring and double vision; stuff like false clouds and shadow galore at times.


Edited by Jeff B1, 27 October 2018 - 09:19 AM.


#25 Kokatha man

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Posted 27 October 2018 - 06:39 PM

The seeing had degraded noticeably between our earlier capture images & those revealing Arsia Mons & shadow etc later that night, although the shadow is quite clearly seen in the latter...one of the miracles of modern cmos cameras I guess Jeff!

 

I thought that the changing Sun angle as they rotated more fully into view might've made captures taken after the red filter one I posted here in Brett's thread less discernible, but it seems we have several before & after that time that give a clear view.

 

I'm still processing them but an iR610nm filter capture is probably the best taken at UT 12:16.....still considering how best to present them & might even contemplate the abomination of an iR-rgb if it gives a good image - might be worth placing on our website or start a new thread on what is an old(er) occurrence, but in any event I won't monopolise Brett's thread here anymore with any additional images! lol.gif

 

My cataracts have been fairly stable for some years Jeff & so far they aren't causing any real problems...probably wouldn't be much chop looking into an ep trying to discern subtle features nowadays but my eyes still function well on the laptop screen for focusing, although I have to admit that there are certain "tricks" to recognising just how sharp the focus is on different planets... wink.gif

 

With the poor contrast up till very recently (a product of the dust storm) accurate focusing on Mars has been one darn difficult job this apparition!




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