Penitentes are snow and ice features formed by erosion that, on Earth, are characterized by bowl-shaped depressions several tens of centimetres across, whose edges grade into spires up to several metres tall1,2,3. Penitentes have been suggested as an explanation for anomalous radar data on Europa4, but until now no penitentes have been identified conclusively on planetary bodies other than Earth. Regular ridges with spacings of 3,000 to 5,000 metres and depths of about 500 metres with morphologies that resemble penitentes have been observed by the New Horizons spacecraft5,6,7,8 in the Tartarus Dorsa region of Pluto (220°–250° E, 0°–20° N). Here we report simulations, based upon a recent model3 representing conditions on Pluto7,9, in which deepening penitentes reproduce both the tri-modal (north–south, east–west and northeast–southwest) orientation and the spacing of the ridges of this bladed terrain. At present, these penitentes deepen by approximately one centimetre per orbital cycle and grow only during periods of relatively high atmospheric pressure, suggesting a formation timescale of several tens of millions of years, consistent with crater ages. This timescale implies that the penitentes formed from initial topographic variations of no more than a few tens of metres, consistent with Pluto’s youngest terrains.
This is a preview of subscription content
Subscribe to Nature+
Get immediate online access to the entire Nature family of 50+ journals
Subscribe to Journal
Get full journal access for 1 year
only $3.90 per issue
All prices are NET prices.
VAT will be added later in the checkout.
Tax calculation will be finalised during checkout.
Get time limited or full article access on ReadCube.
All prices are NET prices.
Nichols, R. L. Nieves penitentes near Boston, MA. Science 89, 557–558 (1939)
Lliboutry, L. The origin of penitentes. J. Glaciol. 2, 331–338 (1954)
Claudin, P., Jarry, H., Vignoles, G., Plapp, M. & Andreotti, B. Physical processes causing the formation of penitentes. Phys. Rev. E 92, 033015 (2015)
Hobley, D. E. J. How rough is the surface of Europa at lander scale? Lunar Planet. Sci. Conf. XLIV, abstr. 2432 (2013)
Moore, J. M. et al. The geology of Pluto and Charon through the eyes of New Horizons. Science 351, 1284–1293 (2016)
Stern, S. A. et al. The Pluto system: initial results from its exploration by New Horizons. Science 350, aad1815 (2015)
Gladstone, G. R. et al. The atmosphere of Pluto as observed by New Horizons. Science 351, aad8866 (2016)
Moore, J. M. et al. Sublimation as a land-form shaping process on Pluto. Icarus http://dx.doi.org/10.1016/j.icarus.2016.08.025 (in the press)
Toigo, A. D. et al. General circulation models of the dynamics of Pluto’s volatile transport on the eve of the New Horizons encounter. Icarus 254, 306–323 (2015)
Cathles, L. M., Abbot, D. S. & MacAyeal, D. R. Intra-surface radiative transfer limits the geographic extent of snow penitents on horizontal snowfields. J. Glaciol. 60, 147–154 (2014)
Zalucha, A. M. & Gulbis, A. A. S. Comparison of a simple 2-D Pluto general circulation model with stellar occultation light curves and implications for atmospheric circulation. J. Geophys. Res. 117, E05002 (2012)
Toigo, A. D., Gierasch, P. J., Sicardy, B. & Lellouch, E. Thermal tides on Pluto. Icarus 208, 402–411 (2010)
Brown, G. N. Jr & Ziegler, W. T. in Advances in Cryogenic Engineering Vol. 25 (eds Timmerhaus, K. & Snyder, H. A. ) 662–670 (Plenum, 1980)
Young, L. A., Elliot, J. L., Tokunaga, A., DeBergh, C. & Owen, T. Detection of gaseous methane on Pluto. Icarus 127, 258–262 (1997)
Hirschfelder, J. O., Curtiss, C. F. & Bird, R. B. Molecular Theory of Gasses and Liquids (Wiley, 1954)
Sussman, G. J. & Wisdom, J. Numerical evidence that the motion of Pluto is chaotic. Science 241, 433–437 (1988)
Applegate, J. H., Douglas, M. R., Gürsel, Y., Sussmann, G. J. & Wisdom, J. The outer solar system for 200 million years. Astron. J. 92, 176–194 (1986)
Earle, A. M. & Binzel, R. P. Pluto’s insolation history: latitudinal variations and effects on atmospheric pressure. Icarus 250, 405–412 (2015)
Trowbridge, A. J., Melosh, H. J., Steckloff, J. K. & Freed, A. M. Vigorous convection as the explanation for Pluto’s polygonal terrain. Nature 534, 79–81 (2016)
McKinnon, W. B. et al. Convection in a volatile nitrogen ice-rich layer drives Pluto’s geological vigor. Nature 534, 82–85 (2016)
Bergeron, V., Berger, C. & Betterton, M. D. Controlled irradiative formation of penitentes. Phys. Rev. Lett. 96, 098502 (2006)
Mullins, W. W. & Sekerka, R. F. Stability of a planar interface during solidification of a dilute binary alloy. J. Appl. Phys. 35, 444 (1964)
Allison, M. & McEwen, M. A post-pathfinder evaluation of aerocentric solar coordinates with improved timing recipes for Mars seasonal diurnal climate studies. Planet. Space Sci. 48, 215–235 (2000)
Stansberry, J. A. et al. A model for the overabundance of methane in the atmospheres of Pluto and Triton. Planet. Space Sci. 44, 1051–1063 (1996)
Lupo, M. J. & Lewis, J. S. Mass-radius relationships and constraints on the composition of Pluto. Icarus 42, 29–34 (1980)
Brown, R. H., Johnson, T. V., Kirk, R. L. & Soderblom, L. A. Energy sources for Triton’s geyser-like plumes. Science 250, 431–435 (1990)
Melosh, H. J. Planetary Surface Processes Ch. 9 (Cambridge Univ. Press, 2011)
J.E.M. was supported in this work by a Discovery Grant (436252-2013) from the Natural Sciences and Engineering Research Council of Canada (NSERC) and C.L.S. was supported by a fellowship under the Integrating Atmospheric Chemistry and Physics from the Earth to Space (IACPES) Collaborative Research and Training Experience (CREATE) programme of NSERC. We thank the New Horizons team for their efforts to plan, develop and operate a mission to explore Pluto. The successful fly-by of 2015 provided publicly available data and peer-reviewed analysis of the surface and atmosphere that enabled the research presented in this paper.
The authors declare no competing financial interests.
Reviewer Information Nature thanks D. Abbott and the other anonymous reviewer(s) for their contribution to the peer review of this work.
Extended data figures and tables
Initially a parabolic depression in a flat, horizontal surface, model penitentes were generated by rotating by the angle ω, with the positive sense indicated. The light grey region indicates the area in shadow under this orientation and projected solar zenith angle θ, shown in the negative sense.
Extended Data Figure 2 A sample run of the penitente geometry for LS = 230°, showing the distribution of received energy.
This orientation of penitentes at this time of year displays a concentration of energy near the bottom, arising from orientation and self-illumination.
About this article
Cite this article
Moores, J., Smith, C., Toigo, A. et al. Penitentes as the origin of the bladed terrain of Tartarus Dorsa on Pluto. Nature 541, 188–190 (2017). https://doi.org/10.1038/nature20779
Nature Communications (2022)
Nature Geoscience (2020)
Equatorial mountains on Pluto are covered by methane frosts resulting from a unique atmospheric process
Nature Communications (2020)
Nature Astronomy (2019)
Space Science Reviews (2018)