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Originally posted by elevenaugust An amateur astronomer in West Chester, Penn. took a picture of a curious Martian cloud several nights ago Also, it moves with the planet (ruling out dust motes on the sensor) and seems to rise over the limb.
I think you have made a few rather astute comments regarding the feature seen on the limb of Mars recently. My thinking coincides with comments made by Christpohe Pellier, Richard McKim and others who have mentioned high altitude clouds as an explanation.
The MARCI weather map for March 12-18 has been posted and while it does not include March 20th, the date of Wayne's image, the map does cover the date of Marc DELCROIX’s image of March 12. I don’t see any indication of unusual dust or cloud activity in the March 12-18 map so I think that would tend to rule out the possible but highly unlikely scenarios of major impacts with their attendant dust plumes, major volcanic eruptions or some of the other interesting but fanciful explanations.
We know that the Olympus Mons orographic cloud should be at an altitude of 20 km at this season (Ls 87 degrees) and this cloud is not seen to project beyond or above the limb/terminator as far as I am aware. The
clouds within the equatorial cloud belt (ECB) may start out at low elevation on the morning side of the planet but rise to higher altitudes during the afternoon. As sunlight warms the surface, the escaping IR radiation warms
the CO2 atmosphere which raises the altitude of the water ice condensation layer. However, I think the ECB usually rises up to an altitude of only 10-20 km. So, to go one step further than the high altitude clouds already
mentioned my guess would be that they are mesospheric clouds which are at an altitude of 40-80 km.
More specifically, considering the proximity of the clouds to the terminator I would suggest they are similar to noctilucent clouds in Earth's atmosphere. One of my meteorology text books defines noctilucent clouds as "luminous night clouds". Since as Roger points out below, if this feature is high altitude clouds, they are not projecting above the actual limb of the planet but are high enough to be illuminated by sunlight, are seen beyond the terminator but against the night side of the surface, so are viewed in maximum contrast. I have only read a half dozen papers on mesospheric clouds so my knowledge is decidedly weak in this area as opposed to the lower altitude cloud types we usually see.
One of these papers (McConnochie et al, 2010) mentions that they could only identify two examples where an overlay of THEMIS-VIS images of mesospheric clouds could be matched up with a similar pattern of clouds as seen in the MOC daily global maps by Wang & Ingersoll so it may not be surprising that I did not see anything unusual in the MARCI maps. Dust, water ice and CO2 ice aerosols have all been observed in the martian mesosphere.
There does not appear to be an excess of dust in the MARCI images and the McConnochie paper states, "the mass of condensate is at least four times greater than the maximum amount of water vapor that can be contained in an atmospheric column, the condensate is most likely CO2 ice". I always assumed (apparently wrongly so) that the optical depth of martian mesospheric clouds would be considerably less (more tenuous) than lower altitude water ice clouds and that we would in all likelihood not be able to see high altitude CO2 ice clouds in ground based imagery. At least in some cases "particle sizes and optical depths also happen to be comparable to those of lower atmosphere water ice clouds"
(McConnochie 2010). I assume this last statement is referring to the ECB clouds as the volcano induced orographic clouds often appear much thicker with higher optical depth as compared to the ECB. Two types of mesospheric cloud forms seem to dominate, cumulonimbus and cirrus. The cumulonimbus clouds may at times have a clumpy structure which may indicate convective action. The cirrus clouds are by far the more numerous and may appear as filamentary structures sometimes organized in consecutive waves.
Certainly there are a few questionable aspects to the concept of this feature being mesospheric clouds, my own bias in thinking we can't see these things for one. Also, I have no idea if CO2 ice clouds should be visible in
all three primary RGB filtered images.
Cloud formation high up in the atmosphere can be induced by gravity waves but I have not researched the idea enough to know if this would be a preferred location for a quasi-stationary cloud. Is this feature moving in longitude and/or latitude?
To MIR, can you provide a comment on this feature we have been seeing? I would love to hear a more informed opinion even if to find my speculation is oh so wrong. BTW, thanks so much for sending the link to the Ashima web site. Love those maps!
McConnochie et al, THEMIS-VIS observations of clouds in the martian mesosphere: Altitudes, wind speeds, and decameter-scale morphology, Icarus 210 (2010) 545-565
With Tim McConnochie's THEMIS/VIS obs, we used the presence of the mesospheric clouds to get the cloud height from parallax. If any one wants to get hold of the paper, it's on the www.ashimaresearch.com webite under publications (also checkout Ai Inada's paper there for more cool, high-res THEMIS VIS images and analysis). Actually, based on the stuff from this email list I've scheduled (more acurately Phil Christensen and his great team at ASU have scheduled) some THEMIS VIS imagery over the area where it looked like the limb feature was back on the 21/22nd. I know it's very unlikely to still be there, but figured we'd be remiss in not looking as quickly as we could.
MARCI is likely to have seen the limb feature in their full data (since the camera is effectively limb-to-limb) but it's a question of whether they process and release that stuff. Prior MARCI imaging has seen mesospheric clouds. I also need to contact the MCS team, they've seen some awesome thermal "arches" in data where the thermal IR array is pushed along ahead or behind the spacecraft and the effective rising and setting of the clouds show up as opacity in channels that should only see gas - they were very cool as we saw them with MCS very quickly after we got in to orbit. These are up at the 80km ish height, so we assume we're seeing the same thing in the THEMIS, MCS, MARCI (and Pathfinder) data. There's a link to a 2011 conference abstract by David Kass from the MCS team here showing the thermal IR "arches":
My guess is that this probably was a major mesospheric cloud being caught in sunlight where the sun had rise at the cloud but not on the underlying ground. This was seen at the Mars Pathfinder site where these clouds were seen in about an hour before sunrise:
That said, unless I get t see the MARCI images (will eventually when they get PDS released) and either the MCS data (which I'll try to check next week) or THEMIS (which probably won't show anything a week later), anything is on the table. Great thing about Mars is it keeps throwing us great, cool stuff.
Mark Richardson, Ashima Research
Everything has to have a 'first'. You can't just skip straight to the second.
Originally posted by wutz4tom
Equally interesting is the fact that it wasnt until the first astromer spoke up,(or got the okay to??)..Only then did others start to come forward...
Originally posted by Phage
reply to post by masqua
Take a look at this Hubble image. The left limb of Mars in the May 17 1997 image.
Whatever it is, it's similar.
Originally posted by Qumulys
reply to post by DissentFromDayOne
I'm sorry, but why are you even posting in a thread about planets if you don't believe in them?
You can actually hire out some telescopes online, might be worth using one so you can see with your own eyes, then will you believe?
*pulls out hair
Originally posted by FraternitasSaturni
I found a strange feature over Acidalia (top left of the animation below)
Acidalia Planitia is a plain on Mars. It is located between the Tharsis volcanic province and Arabia Terra to the north of Valles Marineris, centered at 46.7°N 338.0°E. The plain contains the famous Cydonia region at the contact with the heavily cratered highland terrain.
It has been hypothesized by J.E.Brandenburg from Orbital Technologies Corp. that a large natural nuclear reactor in the northern Mare Acidalium, near the large, shallow depression north of Acidalia Colles (similar to Oklo on Earth) underwent catastrophic meltdown.
Originally posted by DissentFromDayOne
reply to post by elevenaugust
ROFL ... if you think that is a photo of "mars" I have some seaside property in Arizona to sell you.
THERE ARE NO PLANETS, just the sun, moon, earth, and stars.
Look again at that photo...it looks like a smooth orange or old tennis ball with some goo on it.
Welcome to truth with a capital T:
Rev 12:9 And the great dragon was cast out, that old serpent, called the Devil, and Satan, which deceiveth the whole world: he was cast out into the earth, and his angels were cast out with him.
When the word of God (the King James 1611 Bible---which is perfect and never wrong) tells you the whole world is deceived, then yes, the whole world is deceived.
Turn to Jesus.....today could be your last day....
Originally posted by MamaJ
reply to post by WarriorOfTheLight
Why would we not see a HMO if there was one? Behind the Sun?
I read the other day about a Planet lurking right outside the Solar System but that would not affect Mars, or would it?
I have no idea what the image could be but If I had to guess I would guess volcanic activity.