New Horizons: First Mission to Pluto and the Kuiper Belt

NASA's New Horizons is the fastest spacecraft ever launched from Earth (at the time of launch in 2006), and the first to visit Pluto and the Kuiper Belt. On July 14, 2015, it flew within 12,500 km of Pluto's surface — completing a 9.5-year journey through the outer solar system — and returned the first detailed images of the dwarf planet, revealing a world far more complex and geologically active than scientists ever expected.

What New Horizons Found at Pluto

• Tombaugh Regio — A vast heart-shaped plain, informally named for Pluto's discoverer, made of nitrogen ice glaciers actively flowing like a slow-motion glacier on Earth
• Towering Mountains — Mountain ranges up to 3,500 meters tall made of water ice — remarkably young (geologically speaking, only 100 million years old)
• Thin Atmosphere — Pluto has a wispy nitrogen atmosphere that expands when near the Sun and collapses as it moves away
• Haze Layers — Photochemical hazes in Pluto's atmosphere create stunning blue skies and deposit dark reddish material on the surface
• No Impact Craters on Tombaugh Regio — proving the surface is being actively refreshed, indicating possible internal heat source

Charon: Pluto's Giant Moon

Pluto's largest moon, Charon, is so large relative to Pluto (about half Pluto's diameter) that the two form a true double-planet system — they orbit a common center of gravity that lies between them, outside of Pluto itself. New Horizons revealed Charon's geology to be equally surprising: a deep canyon system stretching 1,600 km and a dark reddish polar cap (Mordor Macula) stained by tholins — complex organic molecules formed when Pluto's escaping atmosphere freezes onto Charon's poles.

What Is the Kuiper Belt?

The Kuiper Belt is a vast disc of icy bodies extending from Neptune's orbit (30 AU) to about 50 AU from the Sun. It contains hundreds of thousands of objects including dwarf planets like Pluto, Eris, Makemake, and Haumea. In 2019, New Horizons flew past Arrokoth (2014 MU69) — a contact binary Kuiper Belt Object — providing the most detailed look ever at a primordial solar system remnant.

Where Is New Horizons Now?

By 2026, New Horizons is more than 57 AU from the Sun — well past Pluto's orbit and traveling deeper into the Kuiper Belt and beyond. It continues to study the environment of the outer solar system with its remaining instruments, measuring the cosmic background radiation, the density of interplanetary dust, and searching for distant Kuiper Belt Objects to potentially fly by in the future, if its power supply permits.