Topographic prominence, the measure of how a landform rises independently above its surroundings, provides a universal way to compare landforms – even beyond Earth. Planetary scientists have applied this metric to understand landforms such as mountains on the Moon, Mars and other bodies, showing its versatility in interpreting landscapes beyond Earth:

[Bailey et al., 2020, LPSC Abstract #1753 https://www.hou.usra.edu/meetings/lpsc2020/pdf/1753.pdf] focused on mountains surrounding the South Pole-Aitken (SPA) basin in a preliminary study aimed at investigating the structure of basin rings. For each studied mountain, they recorded base elevation, summit elevation, average relief and topographic prominence, defining prominence as “the relief of the mountain relative to the lowest encompassing 100m contour interval that contains no taller peak.” This definition is conceptually aligned with the Ribus framework, which identifies peaks with ≥1000 m prominence on planetary surfaces.

On Mars, [Richardson et al., 2021, JGR Planets https://doi.org/10.1029/2020JE006620] similarly quantified the metric in their study of small volcanic vents in the Tharsis province. They defined topographic prominence as “the vertical relief between a peak and its key col, which is the lowest surrounding closed contour line within which the peak lies at the highest elevation,” and illustrated this with Pavonis Mons, which they report as having a prominence of 6.6 km. This value aligns with the Mars catalogue on the World Ribus editors’ web-app (https://spaceribus.pythonanywhere.com/mars), which lists all points on Mars with ≥1 km topographic prominence based on the blended MOLA + HRSC digital elevation model, including precise coordinates and elevations of both summits and their key cols.

Richardson et al. go further in clarifying hierarchical relationships within the Tharsis Montes. They note that contours enclosing Pavonis Mons below 7.4 km mean datum also enclose the higher summit of Arsia Mons at 17.6 km, making Arsia the parent peak of Pavonis. They report a prominence of 12.1 km for Arsia Mons, with Ascraeus Mons as its parent. The Mars catalogue on the World Ribus editors’ web-app broadly agrees, listing P12,329 (where P is prominence in metres) for Arsia Mons and confirming Ascraeus Mons as the most prominent volcano in the Tharsis Montes.

Crucially, Richardson et al. explicitly justify their choice of topographic prominence over alternative measures of volcanic height. Mapping lava flow fronts can misrepresent a volcano’s true structural base because flows may be buried, resurfaced, or degraded, leading to systematic underestimation. Break-in-slope detection is more formal geomorphically but depends on a priori parameter choices such as slope thresholds and smoothing scales, which may not be appropriate across a large and morphologically diverse vent catalogue. By contrast, prominence defines edifice height relative to the highest connecting saddle, removing boundary ambiguity and minimising subjective parameterisation. The authors therefore adopt prominence as a consistent, DEM-driven metric particularly suited to the resurfaced and structurally complex landscapes of Tharsis.

Topographic prominence also features in interpretive planetary geology. [Spudis et al., 1992, LPSC XXIII Abstract #1797 https://www.lpi.usra.edu/meetings/lpsc1992/pdf/1797.pdf] discussing radar topography of the Humorum basin, referred to the “exceptional topographic prominence” of the Gassendi and Letronne rings. Later, [Spudis et al., 2013, JGR Planets https://doi.org/10.1002/jgre.20059], in their study of large lunar shield volcanoes, attributed the topographic prominence of the Aristarchus plateau principally to structural uplift associated with formation of the Imbrium basin, only partly enhanced by volcanic overplating. On Callisto, [White et al., 2015, JGR Planets  https://doi.org/10.1002/2015JE004846] showed that ice preferentially “colonizes terrain of high topographic prominence” – specifically crater rims of kilometre scale – because such crests experience reduced thermal reradiation. On Mercury, [Wright et al, 2018, https://doi.org/10.1002/2017JE005450] identify a feature with “the highest topographic prominence within Heaney (crater)” as a candidate volcano.

Even when researchers do not explicitly reference “topographic prominence,” they often reason in ways that are conceptually equivalent. In classical prominence, a peak’s independence is defined by the elevation difference between its summit and the key col (saddle) connecting it to higher terrain. Similarly, in planetary studies, saddles between landforms often determine connectivity, isolation, or potential interactions, such as overflow, sediment transport, or geomorphic integration.

For example, on Mars, [Tanaka et al, 2003, JGR Planets https://doi.org/10.1029/2002JE001908] examined the saddles between Utopia, Borealis, and Isidis basins to infer whether catastrophic water overflow could have connected these regions. They state the Utopia–Borealis saddle sits at -4340 m, and the Utopia-Isidis saddle at -3520 m. These elevations act as thresholds: an ocean or large flood exceeding them would have breached the basins, producing deep channels and modifying pre-existing features, whereas lower flows would have left features intact. In this sense, the saddles govern whether basins act independently or are hydrologically connected.

On Venus, [Kiefer et al, 1991, JGR Planets https://doi.org/10.1029/91JE02221] describe the equatorial highlands of Aphrodite Terra, which include the Ovda and Thetis regions. The authors note that Ovda reaches 4.5-5 km, Thetis 3.5-4 km above mean planetary radius, but the saddle connecting them is only ~2 km in elevation. The substantial drop relative to each peak indicates that these highlands are separate topographic units, rather than a single continuous one. Ovda and Thetis are therefore better interpreted as closely spaced yet distinct, quasi-circular highland units.

These examples highlight that peaks, basins, or highlands may all be evaluated in terms of their relative heights above surrounding saddles, and the cols themselves often mark morphologically and geologically significant connection or integration zones. Recognising these thresholds allows researchers to infer past hydrology, tectonics and volcanic or sedimentary processes.

Just as prominence defines the independence of summits, the same framework can be inverted to describe topographic depressions. Basins, craters and calderas may be characterised by how deeply they descend relative to their lowest enclosing saddle, forming what may be termed “Negative Ribus” should their anti-prominence exceed 1,000 metres. Anti-prominent landforms are defined not by elevation above surrounding terrain, but by depth below it. Impact structures, collapsed volcanic centres and subsided regions can therefore be analysed using the same saddle-based logic that defines mountains, offering a unified way to map both positive and negative relief across planetary surfaces.

On Earth, topographic prominence is commonly used to describe mountain features above sea level, and can also be mirrored in the oceans, where seamounts – sometimes precisely defined as submerged “peaks rising more than 1000m above the surrounding sea floor” http://news.bbc.co.uk/earth/hi/earth_news/newsid_9409000/9409316.stm – demonstrate a similar principle. While seamount definitions rarely mention the word ‘prominence’, the 1000 m figure matches perfectly with the Ribus concept and the contrast with the surrounding sea floor emphasises how topographic prominence defines a feature’s individuality. This raises intriguing possibilities: if similar underwater mountains exist elsewhere in the Solar System or on exoplanets, the same prominence-based approach could help identify them.

The conceptual clarity and generality of topographic prominence have also encouraged its adaptation beyond physical topography. A clear example is provided by [Zollo & Weigel, 2023, Advances in Space Research https://doi.org/10.1016/j.asr.2023.10.032] in satellite manoeuvre detection. As Earth’s orbit becomes increasingly crowded with active satellites and debris, it is essential to know when a spacecraft fires its thrusters, since even small manoeuvres alter orbital paths and affect collision risk assessments.

When operators do not provide manoeuvre information, analysts must infer such events indirectly. Zollo and Weigel focus on off-line detection: rather than monitoring satellites in real time, they analyse historical records of orbital parameters, such as altitude or longitudinal position. In these time series, a thruster firing appears as a sudden jump or dip embedded within gradual background trends and measurement noise. Traditional methods flag events based on statistical thresholds – often using separate criteria for upward and downward deviations – which can struggle in uneven or asymmetric signals. To overcome these limitations, the authors treat the orbital record as an abstract topography. A manoeuvre is analogous to a mountain peak – positive or negative – that must stand out from its local surroundings. They explain:

“Topographic prominence is used in mountain topography to measure the height of a peak relative to the lowest contour line encircling it but containing no higher summit within it. Its usage is advantageous especially when it comes to confront different signals belonging to different manoeuvres.”

By measuring the prominence of each deviation relative to its local baseline rather than relying solely on global statistical limits, they can detect both orbit-raising and orbit-lowering events using a single, unified threshold. This approach simplifies the detection framework and reduces false identifications in complex or asymmetric signals.

Another interesting example comes from astronomical image analysis, where researchers face the challenge of distinguishing individual stars in crowded or defocused fields. In wide-field transit surveys, such as HATNet, SuperWASP, or the Kepler mission, point-spread functions (PSFs) of stars are often distorted, defocused, or donut-shaped. Consequently, a single star can produce multiple local intensity maxima in a digital image, making naïve peak detection prone to splitting a single source into several “false stars.”

To address this, [András Pál, 2009, https://doi.org/10.48550/arXiv.0906.3486] applied the classical notion of topographic prominence to a discrete pixel grid. Pixel intensity is treated as elevation, and local maxima are treated as “peaks” in a virtual topography. The algorithm identifies the key saddle for each local maximum – effectively the lowest point that connects it to a brighter neighboring maximum – and computes the prominence as the intensity difference between the peak and its saddle. Local maxima with low prominence are considered substructures of a larger stellar PSF and are merged with their parent maxima, whereas highly prominent maxima are retained as independent stars.

In effect, a concept developed to compare mountain summits proves equally powerful in distinguishing meaningful ‘peaks’ across very different kinds of landscapes. It operates within the dynamic, invisible terrain of satellite motion and in the pixelated intensity fields of astronomical images, where it separates genuine stars from artefacts. More generally, it extends across planetary surfaces: sizing volcanic vents on Mars, determining the independence of ‘continents’ on Venus, comparing seamounts beneath the oceans, and even measuring the anti-prominence of lunar craters.