Olympus Mons, a colossal shield volcano on Mars, holds the distinction of being the largest known volcano in the entire solar system. Its immense scale, standing over 21.9 kilometers high, makes its discovery timeline a complex journey spanning centuries of astronomical observation. The process involved moving from vague telescopic sightings to a formal descriptive name, and finally to a definitive scientific confirmation of its true nature.
Early Telescopic Observation of Mars
The region where Olympus Mons sits was first noted by 19th-century astronomers using early, ground-based telescopes. The Italian astronomer Giovanni Schiaparelli made observations in the late 1800s that included this area. He and other observers consistently noticed a bright, hazy spot that stood out from the surrounding reddish terrain.
This feature’s most striking characteristic was its persistence, remaining visible even when the rest of the planet was obscured by massive Martian dust storms. Schiaparelli correctly deduced that any feature that could pierce the planet-wide dust veil must possess an extremely high elevation. However, the technology of the time was insufficient to resolve the spot’s topography, so it was recognized merely as an unusually high-altitude point of interest.
The Naming of Nix Olympica
This bright spot transitioned to a formally recognized, named entity during the standardization of Martian nomenclature. In 1879, Schiaparelli assigned the feature the name “Nix Olympica,” which translates from Latin to “Snows of Olympus.” This name was based on its appearance as a bright albedo feature, suggesting a white cap that astronomers theorized was frost or snow.
The designation of “Nix Olympica” was purely descriptive of its brightness and likely high altitude, not a reflection of its true geologic structure. Astronomers were observing the effect of its altitude, which enabled it to collect frost or rise above the dust, but they lacked definitive proof of its volcanic origin or scale. The name persisted, cataloging the location as a unique bright spot for nearly a century until spacecraft could provide closer inspection.
Definitive Confirmation by Spacecraft
The definitive answer to the nature of Olympus Mons arrived with the first spacecraft to successfully orbit Mars, NASA’s Mariner 9. The probe reached the planet in November 1971, coinciding with one of Mars’s massive global dust storms. Due to the storm, the first images returned to Earth showed only the tops of four massive features poking through the haze.
As the dust settled, Mariner 9’s cameras revealed that the feature previously known as Nix Olympica was an enormous mountain with a distinct caldera at its summit. This provided evidence that the bright spot was an immense shield volcano, establishing its unprecedented size and structure. Following this confirmation in 1972, the name was formally changed from the descriptive “Nix Olympica” to “Olympus Mons,” or “Mount Olympus,” to reflect its true mountainous status.