Blue Skies on Mars

The Color of Mars

The Color of Mars

My science fiction RPG “Red Drums” was about a hollow Phobos containing apparent “tombs” of three-eyed titanic Martians who, when disturbed, proved to be merely sleeping… It also featured a Mars with a blue sky, something unheard of in science fiction since the late 1950s… For whatever reason…


The Color of Mars

author: Holger Isenberg,
, http://mars

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deutscher Text
created: March 1999
last update: 14.June 2000

The Red Planet, this name has to appear in every article of the main-stream press on Mars. The same importance play the little green men in contributions of renowned daily German papers such as Frankfurter Allgemeine Zeitung or Sueddeutsche Zeitung published on the Mars meteorite ALH84001.
Without doubt, the planet appears red with the naked eye in the night sky, whereby our earth viewed from Mars, would appear clearly blue, due to the 70% water coverage in connection with refraction of light in the atmosphere. With a reverse relation of the water land distribution however, rather a brown-green planet would be to be seen from space.
The color of the atmosphere, caused by Rayleigh Scattering[4] at gas molecules, determines thus only in very small amount the color of a planet as seen from space and also directly on the surface!
Why then should the Mars sky, as NASA/JPL PR-department spreads it, should appear red? This coloring is justified if at all, only with the refraction of light at atmospheric dust. But such masses of dust in the atmosphere do not prevail over years on a planet, which has large water-clouds, fog and ground frost, since water would wash these away after short time.
Astronomers at the Hubble Spacetelescope and amateur-astronomers[8] are observing, since long time now, white water-clouds and blueish atmosphere.

Pic. A, Viking 1, Nr. 12b069, 29. August 1976, 12.65 locale Mars time
This picture was created with color-correction derived from the filter response data. (click on picture to view it in original size)
All Viking and Pathfinder images courtesy of JPL/NASA/Caltech.

original data without correction

Indeed, when the first color picture from Viking 1 was received on Earth, the Mars soil was red-brown and the sky was blue, a landscape comparable with the desert of Arizona[3] (fig. A and B).
These are original pictures[5] of the two probes, which are only slightly color corrected to match the filter response values of the camera system. However, the original data without correction, you see on the right of each image, has almost no detectable difference in color.
The Viking cameras operated according to the principle of a color scanner, whereby for different light wave lengths different sensors with separate data channels are used.
To create a colorful picture from this scanner data, a color calibration table is necessary. These tables can be seen near the mast of the parabolic antenna in Pic. A and B and show among grayscales the three basic colours (RGB) of a color monitor.
Already with the naked eye it can be detected there that the colours are correctly shown. Also in Pic.E this can be acknowledged, since the white ground frost (water ice!) supplies a natural color calibration to the white alignment.

Pic. B, Viking 2, Nr. 22a158, 25. September 1976, 11.96 locale Mars time
This picture was created with color-correction derived from the filter response data.

original data without correction

Pic.C shows a typical (NASA-)red Mars picture in the color, taken 18 months later. How does it come to this color change, although the sharply bordered shadows and the otherwise clear colours suggest no atmosphere dust?
The solution of the mystery appears, when using an image processing program: By rising the color-values of blue and green about 50% and 25% one gets to Pic.D, which shows the well known true coloring from Pic.A and B.

Pic. C, Viking 1, 12h016,
11 February 1978, 15.56

Pic. D
Blue amplified by 50%, green around 25%

Pic. E, Viking 2, 21i093,
18.May 1979, 14.24

With the same method[1] we can get true color picture from Mars Pathfinder (Pic. F and G). Note, the sharpness of the Pathfinder images is by far not that good as 20 years ago on Viking as during the Pathfinder mission an information-reducing picture compression algorithm (comparable to JPEG) was used.

Pic. F, Pathfinder,
August1997, source:[6]

Pic. G,
Blue amplified by approx. 50%,
green by approx. 25%

Pic. H, 12e018
03.Jul 1977, 15:20

Pic. I, 12b166
6.Oct 1976, 7:48
Temporary, the surface illumination is really red, caused by dust-storms, darkening the sky. The image on the left was taken shortly after or during such a storm and the diffuse light with almost no shadows is visible. In contrast to this, the image on the right, shows sharp shadows and clear blue sky, the normal condition on Mars.
On the image-data of the Viking- and Pathfinder-Missions, this diffuse illumination is a very rare condition and not the normal state, as NASA seems to publish it with their dull-red pictures.
(click on images for unfiltered original data)

And now the “official” true color view of the Pathfinder landing site published by NASA:

Pic. J, Source:
Original Caption Released with Image:
The true color of Mars based upon three filters with the sky set to a luminance of 60. The color of the Pathfinder landing site is yellowish brown with only subtle variations. These colors are identical to the measured colors of the Viking landing sites reported by Huck et al. [1977]. This image was taken near local noon on Sol 10. A description of the techniques used to generate this color image from IMP data can be found in Maki et al., 1999. Note: a calibrated output device is required accurately reproduce the correct colors.

I don’t know why you should calibrate your output device to view this funny bad-colored picture.



Holger Isenberg, Blue Sky on Mars: http://mars
Robert Shepherd, Synthetic High resolution Viking image:
Vincent DiPietro, Mars: Red sky or blue sky?:,
Department of Meteorology, University of Maryland, Why is the sky blue?: other sources: Blue Sky and Red Sky explained, “What atmosphere would produce a red sky?”
NASA/JPL, Planetary Data System Imaging Node: http://www /
Peter Smith, University of Arizona, Pathfinder panorama: img.html
Filter spectral responsivities on Viking Lander:
Association of Lunar & Planetary Observers: Mars Section:

The best genre to read for creating memorable and fun roleplaying game campaigns

The obvious answer to what to read before creating a campaign for people to really involve themselves in and get stuck into would be – science fiction, fantasy, something “related”.

I really disagree.

I think the best genre to set up your own mind for the campaign is murder mystery, and specifically Agatha Christie.

1. Agatha Christie solves the problem of how to involve random people into adventures in a lot of her novels, particularly the non-Poirot / Marple ones. The stock pulp heroes and heroines she uses are “Dick and Jane” types who are drawn in through a single large coincidence or plucky normal people who have some odd event strike them out of the blue. If you assemble ten or so of these hooks, you have very memorable introductions to use.

2. Agatha Christie starts with observations of people- her hero(ine) sits there annoyed at a fellow traveller on the same bus, or with a character being fired from a job for being rude to the boss, or having just demobbed after a war, or home on leave whilst injured – or penniless after their father dies. These origins are instantly engaging and interesting.

3. Her villains range from the painfully predictable to the truly depraved, but she gets some essentials so right so often- criminals are not as clever as they think they are, they are selfish, and they like to hear themselves talk if they are psychotics. On the other hand people who do something for economic or personal reasons keep quiet. She also uses a good idea a few times- the real crime (or quest) is disguised by the murder (theft, vandalisation, threat) of someone not connected. That way, trying to solve what the victims have in common can never work.

4. Love affairs. She is always sensitive to the fact that people fall in love when thrust together on an adventure- but they don’t always end up with the one they initially fall for! Especially when that person is actually the villain!


The Secret of Chimneys

The Moving Finger

The Pale Horse

And Then There Were None

The Clocks


d20 / GOG campaign : MYTHTROPOLIS

Mythtropolis and all related images, characters and setting (c) and TM 2002, 2014 Jonathan Nolan, all rights reserved worldwide.

Thinking about bringing this back as Conundrum Book 3 or some such- and it is compiled in boxes of maps, character sheets, journals, artwork, models- the works. Tempting to use mixed media instead of inkwork for it… Hm. Anyway:


MYTHTROPOLIS, City of Heroes

by Jonathan Nolan (c) 2002

(originally published in gamebook form and on the Geocities website host 2002)

Mythtropolis is to the heroes of the World of Mystery what New York was to the heroes of Marvel Comics or Gotham to the street heroes of DC Comics.

Mythtropolis is an enormous city, second largest in the known world, with over 1,400,000 sentient beings calling it home. There are whole suburbs of the common demihuman species, as well as a substantial humanoid population in Orctown. Many of these humanoids are ‘Jamoorites’, followers of a fairly recently developed religion that preaches a strict moral code for its worshippers but tolerance for others. There are also many suburbs and sections of the metropolis where a particular class or profession is extremely well represented, with class members from level 0 up to ultimate level present in the city.

The war between the Knights Below and The Web has resulted in a lot of the very powerful people in town perishing, but this power vacuum won’t stay empty very long in such a large city.

–From the Sword and Sorcery Compendium entry on Mythtropolis:

Mythtropolis is a huge city for its world, with approximately 1,400,000 inhabitants. So large has it grown that the rest of the sparsely settled “Wild Lands” kingdom of Haranlarche that it is part of has only a fraction of the realm’s whole population in its villages, crofts and strongholds. Empire City, capital of the Eastern Empire, dwarfs Mythtropolis; not many other civilised settlements come close.

Mythtropolis is a trade port, a meeting place on the border between the nonhuman savagery of the mutated Wild Lands and the settled realms of the east. Where once barbarian herders and warriors struggled to exist on tidal flats, the colossus of Mythtropolis now gazes out to sea, guarding the sea lanes of the Dreadsea along the southern coast of Haranlarche, Kingdom of Crossroads.

The story of Mythtropolis is the story of a city whose true name is ‘Ivyriensteine’.

This is a city that has grown to the size of a metropolis, a mega-city in a sword and sorcery world. Its citizens are mostly fairly normal and average humans, elves, dwarves, halflings, gnomes, lizardfolk and faeries, with the occasional battle between super-powered beings in their midst disrupting the flow of events.

Bards began calling Ivyriensteine (which had previously been nicknamed I-Town) “Mythtropolis” after demigods warred in its streets. In the process some areas of the city were permanently altered. Where they had been merely regular streets and buildings, now somehow they shaded off into other planes of existence, other modes of being. In Ivyriensteine, as in a select group of other places in the World of Mystery, the possible has become wildly improbable and the impossible is becoming likely. Such a place has a terrible need for heroes to oppose the more destructive and outright evil of the prodigies the streets of Mythtropolis produce…


Many adventurers either call Ivyriensteine home or visit it regularly to dump treasure and grab new items, weapons and armour. They also visit its gaming houses, houses of ill repute, temples, taverns and other locales. In addition there are some unique sights in Ivyriensteine that are worthy of special attention, including the huge bronze tableau of statues on the east side of town depicting the super-powered adventurers and heroes of the “golden” and “silver” ages.