— Elon Musk
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| Annotated Mars image – surface regions identified using map comparison |
After capturing Mars with the Celestron NexStar 4SE (102mm) (see the previous post for acquisition and processing details), the next challenge was identifying which Martian surface regions were actually visible in the final image.
Because Mars appears small even near opposition, identifying real surface features requires careful comparison with simulation software and professional Mars reference maps.
Step 1 – Confirming Planet Orientation
To verify the exact rotational phase of Mars at the moment of imaging (April 2, 2012 – 9:47 PM), I used TheSkyX First Light Edition to generate a simulation for that date and time.
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| Mars simulation confirming orientation at time of observation |
This confirmed the planet’s rotation phase and allowed correct alignment between the processed image and global Mars maps.
Step 2 – Comparing with Mars Reference Maps
Next, I compared the processed image with classical Mars albedo maps and Google Mars imagery to identify large-scale surface regions.
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| Google Mars reference imagery |
I also used a classical Mars albedo map from planetologia.elte.hu as an additional reference for identifying named regions.
By carefully comparing brightness patterns between my image and these maps, I was able to identify several Terra and Planitia regions visible in the 102mm Celestron NexStar 4SE image.
Surface Regions Visible
Even with a 102mm aperture telescope, several major Martian regions can be recognized by their brightness contrast:
- Planum Boreum – bright northern polar cap
- Acidalia Planitia – dark northern plains
- Arabia Terra – brighter highland region
- Tempe Terra – brighter northern highland area
- Xanthe Terra – brighter equatorial region
- Noachis Terra – brighter southern highlands
- Terra Meridiani – darker region near Mars’ prime meridian
- Valles Marineris (location) – visible as a darker albedo band adjacent to the brighter Xanthe Terra region; the canyon structure itself is not resolved
While the canyon system of Valles Marineris cannot be resolved in structural detail with a 4-inch telescope, its position can be inferred from the darker albedo band located adjacent to the brighter Xanthe Terra region.
Meaning of the Names
Many Martian surface regions carry Latin names assigned by early astronomers and later formalized by the International Astronomical Union (IAU). These names often describe visual appearance or reference classical geography.
- Planum Boreum – “Northern Plain” (polar region)
- Acidalia Planitia – named after the mythological Fountain of Acidalia
- Arabia Terra – “Land of Arabia”
- Tempe Terra – “Land of Tempe,” named after the Vale of Tempe in ancient Greece
- Xanthe Terra – “Golden-yellow land”
- Noachis Terra – “Land of Noah” (ancient southern highlands)
- Terra Meridiani – “Meridian Land,” near Mars’ prime meridian
- Valles Marineris – “Valleys of Mariner,” named after the Mariner spacecraft
These classical names reflect how early telescopic observers interpreted light and dark patterns long before spacecraft provided high-resolution imagery.
Early telescopic observers such as Giovanni Schiaparelli and Percival Lowell relied entirely on these albedo contrasts to sketch maps of Mars — long before spacecraft provided high-resolution imagery. Interestingly, I later visited Lowell Observatory, where Mars observations played a central role in early planetary astronomy. Seeing those historic telescopes adds perspective to how much careful visual interpretation mattered in pre-spacecraft astronomy.
About Magnification and Resize
During capture I used a 2× Barlow for optical magnification. Later, RegiStax v6.1 “Resize 200%” was applied to enlarge the stacked result. The resize does not create new detail, but it makes subtle brightness variations easier to evaluate and greatly simplifies visual comparison with Mars maps.
Identifying Martian surface features at this scale requires careful study of light and dark regions — almost like solving a planetary puzzle.
This experiment demonstrates that even a modest and affordable telescope like the Celestron NexStar 4SE can reveal real Martian geography when atmospheric seeing cooperates and processing is done carefully.
