New Horizons Reveals Pluto’s Giant Hearts and Hidden Ocean Clues

In July 2015, NASA’s New Horizons zipped past Pluto at about 32,000 mph, capturing most of its high‑resolution imagery in a ~30‑minute window and unveiling Tombaugh Regio—the heart-shaped region whose western lobe, Sputnik Planitia, is a vast nitrogen ice sheet roughly 1,200 by 2,000 km and about 4 km thick. The total data from the encounter amounted to about 6.25 GB, downlinked over about 15 months at 1–4 kb/s as the spacecraft continued outward. These findings — from the nitrogen ice plains to high‑albedo uplands, atmospheric haze, and clues to subsurface oceans — fundamentally reshaped planetary science and set the stage for decades of Pluto research as New Horizons travels beyond the Kuiper Belt.