The formation mechanism of the mutual tidal locking between Pluto and its moon Charon.---**Chart/Diagram Description:** * **Type:** Astronomical image / Photograph of a celestial body. * **Main Elements:** * **Shape:** The central and dominant element is a large, spherical celestial body, appearing to be a planet or moon, set against a completely black background, suggesting space. * **Color and Texture:** The surface of the celestial body displays a varied palette, predominantly in shades of gray, white, and light brown. A prominent, darker reddish-brown region is visible near the top of the sphere, covering a significant portion of its upper-left quadrant. The surface is highly textured and irregular, indicating a rocky or icy composition. * **Surface Features:** Numerous features are discernible across the illuminated surface: * **Craters:** Various circular depressions, likely impact craters, are scattered across the surface, ranging in size. * **Ridges/Cracks:** Several elongated, somewhat linear features resembling ridges, canyons, or large cracks traverse parts of the surface, particularly noticeable in the central and lower-left regions. * **Mountainous/Rough Terrain:** Large areas appear rugged and uneven, suggesting mountainous or highly eroded terrain, interspersed with smoother plains. * **Lighting:** The celestial body is illuminated from the upper-left direction. This causes the left and top portions of the sphere to be brightly lit, while the right and bottom portions gradually recede into shadow, enhancing the three-dimensional, spherical appearance. The terminator (the line separating day from night) is clearly visible, curving from the top-right to the bottom-right of the sphere. * **Labels and Annotations:** There are no text labels, symbols, or numerical annotations present within the image. This image does not contain any questions, options, mathematical formulas, or specific textual information relevant to a problem. It is an image of a celestial body. **Chart/Diagram Description:** * **Type:** Astronomical image of a spherical celestial body. * **Main Elements:** * **Shape:** The central and dominant element is a large, three-dimensional spherical object, appearing as a planetary or dwarf planetary body. * **Background:** The object is set against a solid black background, representing the darkness of space. * **Coloration:** The celestial body exhibits striking coloration and surface features: * Approximately the left and lower-left portions of the sphere are a deep reddish-brown color, characterized by a rugged, cratered, and textured surface. There are lighter, mottled areas interspersed within this region. * Approximately the right and upper-right portions of the sphere are predominantly an off-white to pale yellow color, with some grayish tones. This area appears smoother in parts, but also shows subtle texture and possibly some smaller craters or topographical variations. * A prominent, large, bright, and relatively smooth, heart-shaped or lobe-shaped region of off-white material dominates the center-right of the sphere, contrasting sharply with the darker reddish-brown areas. * **Lighting:** The object appears to be illuminated from the upper-left, creating a sense of depth and highlighting the spherical form, with the lower-right portion of the sphere appearing slightly in shadow. * **Surface Features:** The surface shows distinct geological features, with darker, reddish areas appearing rougher and more heavily impacted (craters), and lighter areas showing smoother plains and perhaps different geological compositions. * **Other Relevant Text:** At the very bottom of the image, typical Android system navigation icons are visible: a square (recent apps), a circle (home), and a triangle (back). These are not part of the content to be extracted as a question or problem description. **Chart/Diagram Description:** * **Type:** Astronomical photograph/image. * **Main Elements:** The image displays two spherical celestial bodies against a dark, featureless background, which represents space. * **Larger Celestial Body (Pluto):** * Positioned prominently in the lower-right portion of the image. * Its surface exhibits diverse topography and colorations. A large, prominent, bright, off-white to pale yellow region (resembling the "Sputnik Planitia" or "Tombaugh Regio") dominates the right side, appearing relatively smooth. * To the left of this bright region, there is a distinct, dark reddish-brown area with a more textured and possibly cratered appearance. * Other parts of its visible surface show mottled gray, white, and yellowish tones, indicating varied geological features. * **Smaller Celestial Body (Charon):** * Located in the upper-left quadrant of the image, appearing significantly smaller than the larger body. * Its overall color is a darker, more uniform reddish-brown or dull gray compared to the larger body. * A distinct, darker reddish cap or polar region is visible at its top (often referred to as Mordor Macula). * Its surface appears less varied in texture than the larger body but shows some subtle mottling or cratering. * **Relative Position:** The smaller celestial body is positioned above and to the left of the larger celestial body, suggesting they are a binary system (planet and moon). Both are illuminated from the right, casting subtle shadows that define their spherical shapes against the black void of space. * **Labels and Annotations:** No explicit text labels or annotations are present within the image.