Liquids may have existed on the surface of Pluto in the past.

I tell public audiences, don't go to a podiatrist for brain surgery; don't go to an astronomer for planetary science.

We really just didn't realize the diversity of planetary types in our solar system. Pluto looked like a misfit because it was the only one we saw. And just as a Chihuahua is still a dog, these ice dwarfs are still planetary bodies. They're large enough to make themselves round by self gravity, and they surely pass the test of planethood.

When we first sent missions to Jupiter, no one expected to find moons that would have active volcanoes. And I could go down a long list of how often I've been surprised by the richness of nature.

Just because Pluto orbits with many other dwarf planets doesn't change what it is, just as whether an object is a mountain or not doesn't depend on whether it's in a group or in isolation.

To say that what a planet is doesn't matter would be to imply that a planetary scientist couldn't explain to someone what the field is about.

Back before the Kuiper Belt was discovered, Pluto did look like a misfit that didn't belong with either the terrestrials or the giant planets.

One thing scientists do is to find order among a large number of facts, and one way to do that across fields as diverse as biology, geology, physics and astronomy is through classification.

It's very hard to motivate yourself and others with only one goal - particularly if it's complex and you might not get there until years down the road. That's why intermediate goals are so important.

To keep everyone invested in your vision, you have to back up a little bit and really analyze who the different stakeholders are and what they individually respond to.

When I started working with NASA in 1989 as part of a mission to send spacecraft to Pluto, I knew it would take at least 10-15 years to see results of my efforts.

The Kuiper Belt is the largest mapped structure in our planetary system, three times as big as all the territory from the sun out to Neptune's orbit.

I can't imagine how many kids around the world will look at pictures of Pluto and think, 'I want to grow up to be a scientist.'

Science doesn't work by voting. Did people vote on the theory of relativity? No! It's either right or it's wrong. Do we vote on whether genetics is a good theory or not? Of course not.

Either data supports the observations or they don't. Voting doesn't work in science.

Pluto is as far across as Manhattan to Miami, but its atmosphere is bigger than the Earth's.

Whether there's even an ocean on Pluto deep inside is a question I hope New Horizons can address in indirect ways.

Even in our deep ocean, there are ecosystems at work with no light whatsoever down in the deepest portions of the oceanic abyss.

In the mind of the public, the word 'planet' carries a significance lacking in other words used to describe planetary bodies... many members of the public assume that alleged 'non-planets' cease to be interesting enough to warrant scientific exploration.

New Horizons is a very high-tech, small, roughly 1,000-pound spacecraft with the most powerful battery of scientific instrumentation ever brought to bear on a first reconnaissance mission.

The first mission to Mars did not expect to find craters and river valleys, and yet they did. The first mission to Jupiter didn't expect to find ocean worlds and volcano worlds, but they did.

It's interesting - Pluto's almost a brand unto itself. It's the farthest. It's the most diminutive of the classical planets. It's been maligned by astronomers. It's always the one with all the question marks in the back of the textbook in the table. I think children identify with it because it's smaller, kind of cute.

I call Pluto the harbinger.

As a scientist in charge of space sensors and entire space missions before I was at NASA, I myself was involved in projects that overran. But that's no excuse for remaining silent about this growing problem or failing to champion reform.

The costs of badly-run NASA projects are paid for with cutbacks or delays in NASA projects that didn't go over budget. Hence the guilty are rewarded and the innocent are punished.

America's space program has been the envy and inspiration of the world. It has made landmark scientific discoveries that are a lasting legacy of this nation's greatness. It has studied Earth in ways no other nation can match.

Are governments the only entities that can build human spacecraft? No - actually, every human spacecraft ever built for NASA was built by private industry.

Competition-driven innovation and price pressure that commercial practices foster can only make human spaceflight ever more common and U.S. leadership in this domain ever clearer.

Having a diverse suite of U.S.-manned spaceflight systems to access space is inherently robust.

It is only by freeing NASA from routine human transport to low-Earth orbit that we can afford to once again see American astronauts exploring distant worlds.

The Pluto system is much more complex than I had expected.

The basic story for Golden Spike is that we discovered a way to create do-it-yourself Apollo programs for other countries.

If you go to planetary science meetings and hear technical talks on Pluto, you will hear experts calling it a planet every day.

I think that one of the things that will come out of the New Horizons mission is that the public will take a look, and they won't know what else to call Pluto but a planet - and a pretty exciting one.

Pluto and its brethren are the most populous class of planets in our solar system.

The solar system is completely wide open. Almost anywhere we go, I'm sure we would learn a lot.

I'm the one who originally coined the term 'dwarf planet,' back in the nineteen-nineties.

Pluto is showing us a diversity of landforms and complexity of processes that rival anything we've seen in the solar system.

That so many binary or quasi-binary KBOs exist came as a real surprise to the research community.

We're going to find Marses and maybe Earths out in the solar system's attic of the Oort Cloud and the Kuiper Belt.

CASIS has to succeed because for it not to succeed would be a huge setback for the International Space Station program.

CSF and its members believe strongly in the exploration of space of all kinds, including commercial purposes.

Pluto is the new Mars.

I expect New Horizons will see more that Hubble cannot see.

Pluto has a very interesting history, and there is a lot of work that we need to do to understand this very complicated place.

Pluto has strong atmospheric cycles: it snows on the surface; the snows sublimate and go back into the atmosphere each 248 year orbit.

People ask, 'What are the scientific questions you're going to answer?' New Horizons doesn't have any of those; it's purely about raw exploration... We're not 'rewriting the textbook' - we're writing the textbook from scratch.

If the Pluto mission was a cat, then it would've been dead long ago because they only get nine lives, and we've had significantly more than nine stoppages and odd twists and turns.

We were very surprised to find out that Pluto is still geologically alive. It has upended our ideas of how planetary geophysics works.

You could not have predicted the amazing discoveries at Pluto, even though we have been to a couple of objects in the solar system that were at least a little analogous to Pluto.