''As far as I'm concerned, we still have nine planets in the solar system.''
New Horizons space probe co-investigator and Nasa Outer Planet Assessment Group chairwoman Dr Fran Bagenal was clear on her stance about whether Pluto should have been excluded as the ninth planet in the solar system.
In 2006, the International Astronomical Union reclassified it as a dwarf planet.
Dr Bagenal was in Dunedin this week to give the annual John Newton Dodd public lecture, about the New Horizons mission to Pluto, Pluto's largest moon Charon and beyond into the mysterious Kuiper Belt.
The probe was launched in 2006 and collected data about Pluto as it flew past the planet between January 2015 and October last year.
It flew within 12,500km of the surface of Pluto on July 14, 2015, making it the first spacecraft to explore the planet.
Having completed its flyby, New Horizons is now headed for a flyby of Kuiper Belt object 2014 MU69, and is expected to reach it by January 1, 2019.
It will then conduct more distant observations on additional objects in the belt.
Dr Bagenal said there were 3000 large objects in the Kuiper Belt where Pluto was.
''Some of them are as big as Pluto, some of them are even denser and a lot of them have moons.
''The further we look, the more we see. I think there could be a lot more to this solar system that we haven't found yet.
''There could easily be a dozen more planets in our solar system, just waiting to be found.''
Dr Bagenal has participated in many of Nasa's planetary exploration missions, including Voyager (1977-ongoing), Galileo (Jupiter, 1989-2003), Deep Space 1 (flyby of asteroid and comet, 1998-2001), New Horizons (Pluto flyby, 2006-ongoing) and Juno (Jupiter, 2013-ongoing).
Her main area of expertise is the study of space plasmas and planet magnetospheres.
She studies the magnetic fields of planets, the ionised gases trapped in those magnetic fields and the interactions of plasma with the atmospheres of moons and comets.
On the New Horizons mission, her interest is in finding out if the solar wind interaction with Pluto's escaping atmosphere makes it act like a comet.
Dr Bagenal said many discoveries had been made about Pluto and Charon from the data sent back by New Horizons so far.
''We've learnt huge amounts. I thought we were going to see a lump of ice that had some impact craters - you know, a bit like the moon, kind of boring really.
''But no. We see all sorts of dramatic geology, we see convecting ice which is nitrogenised, so the gas that we're breathing is cold enough that it is turned to ice and it convects and turns over like a glacier.
''We're seeing flows of ice, we're seeing stuff in the atmosphere . . . like droplets of oil coming out of the sky, and areas crusted with methane ice.
''We've also found that Pluto has five moons, not just one.''
The data collected is being used to map the surface composition of Pluto and Charon; characterise the geology and morphology of Pluto and Charon; characterise the neutral atmosphere of Pluto and its escape rate; search for an atmosphere around Charon; map surface temperatures on Pluto and Charon; search for rings and additional satellites around Pluto; and conduct similar investigations of one or more Kuiper Belt objects.
