Global albedos of Pluto and Charon from LORRI New Horizons observations

Abstract

The exploration of the Pluto-Charon system by the New Horizons spacecraft represents the first opportunity to understand the distribution of albedo and other photometric properties of the surfaces of objects in the Solar System's "Third Zone" of distant ice-rich bodies. Images of the entire illuminated surface of Pluto and Charon obtained by the Long Range Reconnaissance Imager (LORRI) camera provide a global map of Pluto that reveals surface albedo variegations larger than any other Solar System world except for Saturn's moon Iapetus. Normal reflectances on Pluto range from 0.08-1.0, and the low-albedo areas of Pluto are darker than any region of Charon. Charon exhibits a much blander surface with normal reflectances ranging from 0.20-0.73. Pluto's albedo features are well-correlated with geologic features, although some exogenous low-albedo dust may be responsible for features seen to the west of the area informally named Tombaugh Regio. The albedo patterns of both Pluto and Charon are latitudinally organized, with the exception of Tombaugh Regio, with darker regions concentrated at the Pluto's equator and Charon's northern pole The phase curve of Pluto is similar to that of Triton, the large moon of Neptune believed to be a captured Kuiper Belt Object (KBO), while Charon's is similar to that of the Moon. Preliminary Bond albedos are 0.25±0.03 for Charon and 0.72±0.07 for Pluto. Maps of an approximation to the Bond albedo for both Pluto and Charon are presented for the first time. Our work shows a connection between very high albedo (near unity) and planetary activity, a result that suggests the KBO Eris may be currently active.3

Geologic Landforms and Chronostratigraphic History of Charon as Revealed by a Hemispheric Geologic Map

“…A Dorothy‐sized impact or larger cannot be seen, if it exists, due to its much subtler topography and lack of albedo cues. However, based on the maximum size of impact craters relative to the size of the body across the solar system, it is not unlikely that there is at least one crater larger than Dorothy. Tectonics : Vast chasmata were some of the earliest features observed on approach limb images, and it is certain that other, smaller tectonic features exist, likely across Charon's entire surface. Albedo and Color Variations : Figure b clearly shows color variations across Charon's surface, and Figure a shows additional albedo variations, also described by Buratti et al (). Consequently, it is difficult to speculate about large depressions, tectonics, and craters from the nonencounter imagery: What may appear to be shadows and Sun‐highlighted slopes may instead be albedo markings.…”

Discovery and Physical Characterization of a Large Scattered Disk Object at 92 au

“…The quoted systematic uncertainty is due to variation of the model parameters η and ò. As shown in Figure 4, the measured albedo is higher than that of rocky bodies such as asteroids, and of typical classical KBOs, yet notably smaller than ice-rich dwarf planets Eris (96%; Sicardy et al 2011), Haumea (80%;Fornasier et al 2013), Pluto (72%; Buratti et al 2017), and Sedna (32%; Pál et al 2012), suggesting that 2014UZ 224 has a mixed ice-rock composition. An object of this composition and size is likely to have enough self-gravity to reach an approximately spherical shape in hydrostatic equilibrium (Tancredi & Favre 2008), making 2014UZ 224 a candidate dwarf planet.…”

“…. Size-albedo relations for selected TNO populations including detached and scattered disk objects (Li et al 2006;Santos-Sanz et al 2012), Plutinos (Mommert et al 2012), and dwarf planets (Sicardy et al 2011;Pál et al 2012;Fornasier et al 2013;Buratti et al 2017;Brown & Butler 2017). The object 2014UZ 224 is shown as a filled diamond.…”

Pluto's Beating Heart Regulates the Atmospheric Circulation: Results From High‐Resolution and Multiyear Numerical Climate Simulations

“…(2) The presence of perennial ‐rich deposits in the equatorial regions (Bladed Terrains). On Pluto, these terrains are characterized by a high elevation (above 2 km), parallel sets of “blades” (steep ridges and sharp crests) and a relatively dark albedo (0.5–0.6; Buratti et al, ). They are visible in the Tartarus Dorsa region (east of Sputnik Planitia), but their distinctive absorption is seen in low‐resolution coverage of Pluto obtained during the New Horizons approach phase, suggesting that Bladed Terrain may occur in patches further east along the equator (Moore et al, ; Olkin et al, ).…”