Mars Section        



Early Spring Dust Clouds in the Southern Hemisphere.

 All images are by Teruaki Kumamori














South Polar Cap Recedes Over Argyre Impact Basin

(Please click on image to see full image)    NOTE Argyre’s Latatude is 50S

2020 Mar 20 21 25 26 Montage



A collage of frames showing large expanse of dust clouds

Clyde Foster submitted these images of Mars taken on Feb. 21, 26 and 27. The three show regional dust clouds in and around Hellas.  A composite of the three images has been posted in the album ”Dust storm alerts” on the Mars Observers web site. I’ve attached the composite image above. These clouds are an indication that the SPC is sublimating. Sublimation has been known to generate high-velocity Winds.



Short-lived Dust Clouds Recorded

(Please click on image to see full image)

All images are by Clyde Foster. Besides the short-lived new dust clouds, fragmentation of the SPC dark collar is easily recognized. The SPC dark collar is where sublimation of Ice produces strong winds that sweep away bright dust on the surface exposing dark albedo rock. It is suspected that these winds have produced the recent dust clouds.



February 28, 2020.

Early Dust Storm Alert

Clyde Foster submitted to ALPO images of Mars on Feb. 21, 26 and 27 2020. All three together show what look like dust clouds as far West as Noachis and Eastward covering Hellas and Iapygia Viridis and as far East as the Southern part of Mare Tyrrhenum. There is a dust incursion onto the Northern edge of the SPC in the 2020-02-27 image. A composite of the three images can be found in an album titled “Dust storm alerts” on the Mars Observers web site as well as in the ALPO Mars Gallery. Congratulations to Clyde Foster for the detailed images.
Submitted by Jim Melka


February 12, 2020.

The Mars Pre-Apparition report for the 2020 apparition

Information about the 2020 apparition of Mars can be found here. This link has details about the entire apparition, including:
◙ its apparent size and brightness.
◙ its phase angle and elongation from the Sun.
◙ the changes to expect in its polar caps.
◙ its clouds and possible dust storms.
(The final table in the article, a table of events to observe during this apparition, contains errors as originally written. The corrected table is here.)

Best of luck in observing the Red Planet this apparition. Please share your observations with us on our message list at There you can upload your drawings and images to the photos section, find observing resources, and share in our discussions.


Alerts and Recent Observations of the 2017-2019 Mars Apparition

Dust Storm Alert in Early January 2019, Jan. 6, 7 and 8. Ls 321°

Images courtesy of ALPO Japan


Dust Storm Alert in Early October 2018

Postscript: These dust clouds remained in the South polar regions and within a week they dissipated.

The South polar regions shown above should be observed to see if there is further expansion of the dust storm.
The five images below show Mars with an Ls of about 128. The images from Go and Wesley from March 2016 clearly show the gray-colored CO2 seasonal ice cap in mid-winter. The maximum extent of the CO2 cap has been stated in a professional paper to approximately bisect Hellas. These two images show the edge of the ice cap to be near the Southern rim of Hellas. This indicates that the ice cap at Ls ~128 has already been sublimating. Sublimation produces high winds from where the sublimation is present. From the 2016 images we could have predicted Clyde Foster’s 2018 images would show the gray-colored CO2 ice cap and possibly eeing dust clouds in Hellas. Clyde’s 20180206 and 20180209 images show airborne dust waves in Hellas. There aren’t dust clouds in his 0216 image. Maybe the topography is reducing wind velocity. Note, I suspect the blue-colored H2O ice fog in the 0206 image is hiding the CO2 cap. Good seeing – Jim Melka


Highlights of the 2015-2017 Mars Apparition

Mountains of Mitchel Captured from Ls 253 to Ls 255.

Images of the Hellas-to-Argyre Dust clouds in September are below. In my opinion, these clouds are produced by winds from the continuing sublimation of the CO2 ice cap.


The images below from April 5th to May 9th provide evidence for strong South to North straight-line winds in the Hellas basin from Ls 130 to Ls 150. This period is the middle of winter in the Southern Hemisphere. I propose that the sublimation of CO2 ice produces straight-line winds. With the ice exposed to sunlight, the frozen CO2 sublimes, creating enormous winds up to 400 km/h.[2] Each southern winter, the seasonal CO2 ice cap covers the surface to a latitude of 50°.[28] This means that the Northern edge of the cap bisects Hellas. See Christopher Go’s and Anthony Wesley’s March images below the April and May images. The grey-colored CO2 cap covers the Southern one-fourth of Hellas. It can be deduced that sublimation winds here contribute to the waves of dust in Hellas. Hellas is immense with the South to North diameter about 1,300 miles that is roughly the distance from the US-Canada border to the Pan-handle of Texas. So with that diameter, a significant temperature gradient is likely in the South to North direction that can continue the strong sublimation winds that carry immense waves of dust from South polar regions to the Northern wall of Hellas. These detailed images by Clyde Foster and Efrain Riveras Morales show what I think are the results of these winds. References are courtesy of Wikipedia.
Also note that the floor of Hellas is blue in the April images and white in the May 9th image. A blue color can mean the presence of H2O water vapor but what would be its source? Temperatures in the South polar regions are warm enough for CO2 sublimation but not H2O sublimation. However, the north polar cap of Mars does get warm enough for H2O sublimation. Maybe this is a source of the water vapor. See page 399 of a Traveler’s Guide to Mars by William K. Hartmann published 2003.

First recorded images in this apparition of Wind-Blown Dust Clouds in Hellas. Also, the Northern extremes of the SPC are visible and are grey colored. I don’t remember ever seeing the CO2 part of the SPC in amateur images! Pardon me for saying “Wow”. See images below. About one-fourth of Southern Hellas is covered by the seasonal cap.

Many small features distinguishable on Clyde Foster’s image below!

Images from Feb 17, 2016 to Mar 01, 2016. Have you ever seen such a broad expanse of white clouds over the Martian disk?

Images from February 7th, 8th and 12th 2016

These images show heavy concentrations of H2O clouds in the equatorial regions of Mars. The gaseous clouds sublime from the granular North Polar Cap and move Southward higher and higher in the atmosphere. To the right(West) of the CM orographic clouds are visible over 3 of the Tharsis volcanoes. To the East of the CM, Acidalia planita and Chryse planita are like deep valleys in the Northern hemisphere where possibly an orographic type of action produces equatorial H2O clouds. But, it may be some other mechanism. Also interesting, the green and blue images show bright areas indicating low altitude fogs and clouds above that. Further, the February 7th and 8th red images show the same bright areas that suggest ground frost.

Images from December 11th 2015

The dark markings are sharp and very detailed with Mars only 5″ in diameter on 12-11-2015. A stand out marking is Nilosyrtis that had mostly vanished in the last 5 apparitions. A noticeable change is a new prominent dark band under Sabaeus Sinus. It is late Spring in the Northern Hemisphere. During Spring the North Polar Cap shrinks unevenly leaving ice outcrops such as the one shown here in Uchronia.


Records of Significant Events During the 2013-2014 Mars Apparition

Images Showing the South Polar Hood, the South Polar Cap, the Remnant North Polar Cap that is rarely imaged and the First Appearance of the North Polar Hood.

Hellas, the largest known Impact Basin in our Solar System, has its own weather and often generates high winds at the surface that produce dust clouds to overflow its boundaries. Such is probably the case below.

Images by Manos Kardasis show the South Polar Cap during Winter in the Southern hemisphere. The South Latitude of the Northern edge of the SPC is noted on each image set.

Paul Maxson’s Collage Showing High Resolution Images from March 29, 2014 through June 14, 2014. It is a gold mine of records of the variability in time of features on Mars.

Dust Clouds in the Southern Hemisphere in Mid-Winter!

Image Sets by Christophe Pellier show fine details in the classical features. Note also how the large cloud deck near the Morning limb retains its form and extent even after Mars rotated 36 degrees.

Superb Drawings of Mars in early Northern Summer by Veteran Mars Observer Carlos E. Hernandez


Many Clouds and North Polar Cap Activity Recorded in Early March as Ice is Transferred from Northern Polar Regions to the Southern Hemisphere.

Stunning wide black stripe imaged on Jan. 6th, 2014 that lengthened through March 3rd as a narrower black stripe as the NPC ice continued to shrink uncovering a very dark surface.

Below is a cutaway of a map of the North Polar Cap at Ls = 90 by Chick Capen made from 1969 observations. See the dark figure extending into the NPC at longitude 60 degrees West that is in the same orientation as in the images. The map also shows Mare Boreum and Mare Acidalium to the South of the NPC exactly as shown in the images.

Images showing movements of dust clouds on or near the North Polar Cap and a deep Low-pressure center and its
attendant circular shaped dust storm

Images showing dark ring of sand dunes on North Polar Cap

First sizable dust clouds recorded by ALPO observers in 2013

Four Faces of Mars in September 2013 with a diameter of less than 4.4″ showing many small features!

Four Faces of Mars in September 2013 with great details at a diameter less than 4.4"

2011/2012 Featured Observations

These 3 images show afternoon white clouds over all of the major Tharsis volcanoes. The first two were imaged a day apart while the 3rd was about one month later. During this period, clouds formed almost daily over volcanoes. Note the dust clouds over the Southern perimeter of the North Polar Cap in the first two images. Winds that develop with the sublimation of ice drive the dust clouds and also produce the dark collar that surrounds the NPC. Also note the dramatic decrease in the size of the NPC in the third image. A cloud appears over Olympus Mons, the largest volcano on Mars near the center of each image.

The conditions were perfect for Freddy Willems to image all of Olympus Mons including the caldera on the summit and the gently sloping apron surrounding the summit. The sun was nearly overhead and some white clouds had formed over the Western side of the apron. Everything matches the topographical map.
Olympus Mons

Mysterious feature on the Morning Limb recorded well by Mars Observers. It could be the leading edge of an extremely large cloud of dust and ice being swept Eastward from the Hellas basin. Variability of the size of the cloud could explain its varying appearance. Good seeing from Jim Melka.

Evidence of Early Spring Water Vapor Flow from North Polar Cap Southward

Recent drawings of Mars by two ALPO members

Elysium Mons over a 3-month period in 2011

First Records of the North Polar Cap in 2011

Paul Maxson’s Image on August 06, 2011 shows the Hellas dust cloud of August 04 to have spread Eastward as is the normal case.

Jim Melka’s Image on August 04, 2011 shows a typical dust storm in Western Hellas. See the comparison Image to see Hellas as it usually appears when the skies are clear.

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