TWO MINUTES WITH

Dale P Cruikshank

How did our relationship with Pluto begin?

In 1915, American astronomer and mathematician Percival Lowell predicted a planet beyond Neptune that was causing the motion of Uranus to be irregular, but couldn’t find it before his death in 1916. The search continued and in 1930 Clyde Tombaugh found Pluto, but it wasn’t quite where Lowell predicted and we later found that it is too small to have affected Uranus’s motion.

The debate continues: is Pluto a planet?

As defined by the International Astronomical Union, Pluto is a dwarf planet. Pluto is smaller than Earth’s Moon, but has five moons of its own, active geological processes (moving glaciers) and an atmosphere. In the eyes of many, these and other physical characteristics make Pluto a fully fledged planet.

What were the major challenges and discoveries of New Horizons?

The challenges were getting the spacecraft funded, built and launched, and keeping it working for the 9.5-year trip. Once there, we discovered active geological and atmospheric processes, exposed water ice on the surface and a hazy atmosphere, among other things.

How will the mission end?

New Horizons is on its way to the small Kuiper Belt object 2014 MU69, with a flyby planned for 1 January 2019. The spacecraft will then continue into deep space, eventually leaving the Solar System and running out of power.

DALE P CRUIKSHANK is an astronomer and a co-investigator on New Horizons