2022-2023 Featured Observations

The 2022-2023 Mars apparition is underway! Be sure to check here for updates and examples of observations from your fellow observers. You can send your images and sketches to Mars@alpo-astronomy.org for inclusion in our online gallery and review by the section coordinators (please do follow the file naming guidelines when doing so.)

Ice Storms Near Syrtis Minor

Mars shows a false SPC in early October

Large expanse of bright white dominates the South Polar Regions. The Red-filtered image of 2022-10-05 is the strongest showing

of the three filters especially compared to the Blue-filtered image. This suggests possible CO2 or H2O ice on the ground.

Late September Regional Dust Storm

Early dust clouds observed on September 23, 2022. See below for images.

As of September 30, 2022 dust clouds spread Eastward as far as Hellas in the Southern hemisphere

and Ismenia Lacus in the Northern hemisphere.

Stable Ground Ice North of the South Polar Cap

Two image montages dated 2022-07-25 and 2022-07-29 below provide evidence for ground ice and snowfall. Arrows point to the ice-feature for the blue, green and red filters. The red filter image carries the most weight for ice on the ground. If the feature was a cloud, it would not be be present or only weakly present with a red filter. Over the four-day period the ice was stable and did not sublime. The source could be snowfall providing enough depth to be stable. A polar cold front was imaged at the feature’s location a week before the ground ice was imaged. If the feature was frost then sunlight probably would be enough for sublimation.

July 25, 2022

July 29, 2022

Dust Brightens Dark Markings

Dark features including Mare Hadriacum, Ionium, Iapygia, Yaonis Regio, and Hellespontus are only faintly visible in Clyde Foster’s Febriary 01, 03 and 07 images below. Arrows point to these features. Airborne dust is also normally tan colored in color balanced images. However it is proposed that there is dust is on the ground that is brightening the normally dark features. Next see a montage of his April 01, 02 and 03 images. Arrows point to the same regions and once again show the tan color. However there are no notable changes over a two-month period that suggests at least a semi-permanent ground cover of dust. There may have been recent dust clouds that settled out over these areas.

Images by Claude Foster

2020-2021 Featured Observations

The Mountains of Mitchel aren’t mountains as this feature was characterized in the early 1900s. It occurs on a long elevated region stretching about 800 km long and 300 km wide. Its North-facing edge is a high scarp (cliff) that causes the ground to slope toward the South resulting in a lower sun angle than surrounding regions. This causes a lower temperature of the ice in this region so that the ice doesn’t sublime as quickly as it does in nearby areas.

Mars and its Moons

By Paul Maxson

Clear Example of More Surface Details Visible with Mars Closer to Earth

By Martin Lewis

Rarely recorded views of the residual South Polar Cap from Ls 330° late-southern summer to Ls 353° end-southern summer. Composite images provided by Roger Venable. Note the terminator in the Ls 353° image almost envelopes the SPC. The SPC may have reached its smallest size and should be mostly H2O ice as the surface temperature is still too cold for the ice to sublimate. The surface temperature should continue to decrease as the Sun angle continues to drop in early Fall.

Image by Anthony Wesley shows a composite version of the striations of ice in the SPC as a sawtooth pattern. NASA’s image shows the SPC at a smaller size than Wesley’s image. Names are provided of some of the prominent craters that are resolved.

Ultra-high resolution images show two volcanoes, Elysium Mons and Hectates Tholus. Montage provided by Roger Venable.

The dust clouds of the regional storm shown below continue expanding Eastward and Northward on Nov. 21 and Nov. 24.

The Nov. 15 image shows a large eruption of dust into the air. This dust cloud gradually absorbs solar energy causing the temperature of the cloud to increase. As the temperature of the dust clouds increases, the size of the clouds increases. This process feeds upon itself until the size increases to the maximum possible. Then a massive Dust Cloud on Nov. 17. This is what the author suspects happens by Jim Melka.

South Polar Cap Recedes Over Argyre Impact Basin

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

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 http://groups.io/g/marsobservers. 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 Storms in Early January 2019, Jan. 6, 7 and 8. Ls 321°

>Dust Storm in Early October 2018

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

CO2 Ice Cap Imaged

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 CO2 ice cap to be near the Southern rim of Hellas. This indicates that the ice cap at Ls ~128 has already been sublimating. Sublimation can produce 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.

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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!

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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.

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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

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Images showing dark ring of sand dunes on North Polar Cap

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First sizable dust clouds recorded by ALPO observers in 2013

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

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.

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.

Mars Section