Tombaugh Regio

Description

Tombaugh Regio is a large, light-colored region about 1,590 km (990 mi) across. The two lobes of the feature are geologically distinct. The western lobe, Sputnik Planitia, is smoother than the eastern, and they are of slightly different colors. Early speculation was that the western lobe may be a large impact crater filled with nitrogen snow. Bright spots within the region were initially speculated to be mountain peaks. Photos, released on 15 July 2015, revealed 3,400 m (11,000 ft) mountains made of water ice in the feature; they also showed no craters in this same region. Subsequent data indicated that the center of Sputnik Planitia is rich in nitrogen, carbon monoxide, and methane ices, and that features near the edges of the region show evidence of ice flow such as glaciers, and light material overlying the darker material at the eastern edge of Belton Regio. The surface of Sputnik Planitia is divided into polygonal convection cells and is less than 10 million years old, indicating that Pluto is geologically active.

The feature had been identified as a bright spot for six decades prior to the New Horizons flyby, although it was impossible to image it with enough resolution to determine its shape. Over these six decades the spot had been observed to be dimming.

In 2020, it was found that Tombaugh Regio controlled the wind circulation of Pluto, and could sculpt the landscape on its surface.