Pluto’s dwarf planet status is ‘bulls—-,’ says lead scientist of NASA mission

Pluto is perhaps the most beloved object in our solar system.

So when the New Horizons spacecraft flew past Pluto on July 14 — after a nearly 10-year, 3-billion-mile journey — we weren’t too surprised to learn NASA saw unprecedented traffic to its website, and that the news made the front page of 450 newspapers.

Alan Stern, the lead scientist behind the New Horizons mission, had a lot to celebrate that day:

The mission to Pluto was meant to complete the exploration of the planets in the solar system. But scientists reclassified Pluto from a planet to a “dwarf planet” shortly after New Horizons launched in 2006.

That reclassification split the space-science community.

But Stern has a clear opinion about Pluto’s demotion:

“It’s bulls—-,” he told Tech Insider (and said we could quote him on that).

The problem, Stern said, is that the reclassification largely stemmed from the opinions of astronomers, not planetary scientists. His beef here is that astronomers study a large variety of celestial objects and cosmic phenomena, while planetary scientists focus solely on planets, moons, and planetary systems.

“Why would you listen to an astronomer about a planet?” Stern said.

He compared it to going to a podiatrist for brain surgery instead of a brain surgeon.

“Even though they’re both doctors, they have different expertise,” Stern said. “You really should listen to planetary scientists that know something about this subject. When we look at an object like Pluto, we don’t know what else to call it.”

That’s because Pluto meets the main criteria for planethood: It is rounded by its own gravity.

But there’s more than that, Stern said. Pluto is unexpectedly complex. It has more moons than the entirety of the inner solar system. It possesses close to a million times the amount of atmosphere that Mercury has. The surface has water-ice mountains that could rival the Rocky Mountains here on Earth. Its frozen plains are lined with ridges that scientists think are caused by some kind of ongoing geological process.
“We were just dumbfounded by what a wonderland it is scientifically,” Stern said.

A nonplanet shouldn’t be so active.

“ qualifies in every respect,” he said. Astronomers — not planetary scientists — “made up a definition, which is actually bogus.”

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More in link

> A nonplanet

See thread “the Not-planets”. I suggested “Orb”.

I can’t for the life of me see what’s wrong with “dwarf planet”. It seems perfectly apt in regard to Pluto. Bit of a shame that an interesting mission is being accompanied by this unedifying dick-waving by people who should know better.

Some more Pluto bullshit.

Bubblecar said:

I can’t for the life of me see what’s wrong with “dwarf planet”. It seems perfectly apt in regard to Pluto. Bit of a shame that an interesting mission is being accompanied by this unedifying dick-waving by people who should know better.

Scientists are human, as prone to territorial behaviour and irrational romantic attachments as anyone.

I was somewhat amused by this arch little dig.

“Why would you listen to an astronomer about a planet? … You really should listen to planetary scientists that know something about this subject.”

.

Some alternative rules for “what is a planet?”

1) A planet is an object visible in the night sky. Reject Earth. (eg. Holst’s suite)

2) A planet has at least one moon. Reject Mercury.

3) A planet’s surface is not dominated by craters. Reject Mercury.

4) A planet’s orbit is nearly circular. Reject Pluto and Mercury. Accept Ceres as a planet.

5) A planet’s orbit follows Bode’s Law. Reject Neptune. Accept Ceres and Eris as planets.

6) We understand how a planet formed. Reject Neptune.

7) A planet is smaller than a brown dwarf. Reject Jupiter.

8) A planet has a thick atmosphere. Reject Mercury and Pluto. Accept Titan as a planet.

9) In a double planet the barycentre is outside the surface of the primary. Accept Charon as a planet.

10) A planet rids its orbit of debris. Reject Pluto, Jupiter and Neptune.

11) A planet is the largest object between its semiminor and semimajor axes. Reject Pluto. Accept Ceres, Vesta and Eris as planets.

12) The barycentre of a planet and its star is within the star. Reject Jupiter.

It’s really really difficult to find any definition of planet that rejects Pluto and accepts the other eight.

Why do we reject Neptune for #6?

Bubblecar said:

I can’t for the life of me see what’s wrong with “dwarf planet”. It seems perfectly apt in regard to Pluto. Bit of a shame that an interesting mission is being accompanied by this unedifying dick-waving by people who should know better.

Why do we need to say, “dwarf planet”,. why not just planet?

bob(from black rock) said:

Bubblecar said:

I can’t for the life of me see what’s wrong with “dwarf planet”. It seems perfectly apt in regard to Pluto. Bit of a shame that an interesting mission is being accompanied by this unedifying dick-waving by people who should know better.

Why do we need to say, “dwarf planet”,. why not just planet?

Why not, we have rocky planet and gas planets. Just adds to the information.

Divine Angel said:

Why do we reject Neptune for #6?

Because, according to the accepted cold accretion model of planet formation, Neptune can’t exist. There hasn’t been enough time at that distance from the Sun for a planet that large to have accreted – or to put it another way, according to the best models of planet formation, Neptune ought to be no bigger than Pluto.

dv said:

Pluto’s dwarf planet status is ‘bulls—-,’ says lead scientist of NASA mission

Pluto is perhaps the most beloved object in our solar system.

So when the New Horizons spacecraft flew past Pluto on July 14 — after a nearly 10-year, 3-billion-mile journey — we weren’t too surprised to learn NASA saw unprecedented traffic to its website, and that the news made the front page of 450 newspapers.

Alan Stern, the lead scientist behind the New Horizons mission, had a lot to celebrate that day:

The mission to Pluto was meant to complete the exploration of the planets in the solar system. But scientists reclassified Pluto from a planet to a “dwarf planet” shortly after New Horizons launched in 2006.

That reclassification split the space-science community.

But Stern has a clear opinion about Pluto’s demotion:

“It’s bulls—-,” he told Tech Insider (and said we could quote him on that).

The problem, Stern said, is that the reclassification largely stemmed from the opinions of astronomers, not planetary scientists. His beef here is that astronomers study a large variety of celestial objects and cosmic phenomena, while planetary scientists focus solely on planets, moons, and planetary systems.

“Why would you listen to an astronomer about a planet?” Stern said.

He compared it to going to a podiatrist for brain surgery instead of a brain surgeon.

“Even though they’re both doctors, they have different expertise,” Stern said. “You really should listen to planetary scientists that know something about this subject. When we look at an object like Pluto, we don’t know what else to call it.”

That’s because Pluto meets the main criteria for planethood: It is rounded by its own gravity.

But there’s more than that, Stern said. Pluto is unexpectedly complex. It has more moons than the entirety of the inner solar system. It possesses close to a million times the amount of atmosphere that Mercury has. The surface has water-ice mountains that could rival the Rocky Mountains here on Earth. Its frozen plains are lined with ridges that scientists think are caused by some kind of ongoing geological process.
“We were just dumbfounded by what a wonderland it is scientifically,” Stern said.

A nonplanet shouldn’t be so active.

“ qualifies in every respect,” he said. Astronomers — not planetary scientists — “made up a definition, which is actually bogus.”

—-

More in link

Pluto is perhaps the most beloved object in our solar system.

I would say planet Earth would get this title, followed by “our” moon.

mollwollfumble said:

Divine Angel said:

Why do we reject Neptune for #6?

Because, according to the accepted cold accretion model of planet formation, Neptune can’t exist. There hasn’t been enough time at that distance from the Sun for a planet that large to have accreted – or to put it another way, according to the best models of planet formation, Neptune ought to be no bigger than Pluto.

Does the same apply to Urectum Uranus or is the fact its closer to the sun make all the difference

Cymek said:

mollwollfumble said:

Divine Angel said:

Why do we reject Neptune for #6?

Because, according to the accepted cold accretion model of planet formation, Neptune can’t exist. There hasn’t been enough time at that distance from the Sun for a planet that large to have accreted – or to put it another way, according to the best models of planet formation, Neptune ought to be no bigger than Pluto.

Does the same apply to Urectum Uranus or is the fact its closer to the sun make all the difference

Have they taken into account large objects moving through the solar system during that period?

Large objects external to the solar system

>It’s really really difficult to find any definition of planet that rejects Pluto and accepts the other eight.

——
Proposal drawn up by Uruguayan astronomer Julio Ángel Fernández:

A planet is a celestial body that (a) is by far the largest object in its local population, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape , © does not produce energy by any nuclear fusion mechanism .

Ian said:

>It’s really really difficult to find any definition of planet that rejects Pluto and accepts the other eight.

——
Proposal drawn up by Uruguayan astronomer Julio Ángel Fernández:

A planet is a celestial body that (a) is by far the largest object in its local population, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape , © does not produce energy by any nuclear fusion mechanism .

Define local population for this purpose.

One thing about the current defn is that the

“has cleared its neighbouring region of planetesimals”

part is not a sharp definition. Even the earth hasn’t quite cleared its neighbouring region of planetesimals, for reasonable meanings of neighbouring and planetesimals. Heck, every now and then one of them hits the earth. It means that it could take decades of analysis to determine whether something is a planet.

Any definition is going to have a few fuzzy edges..
Bit like the solar system really:)

Ian said:

Any definition is going to have a few fuzzy edges..
Bit like the solar system really:)

Yeah but there’s no need to make it harder than it needs to be. The Fernández proposal is straightforward and uncontroversial.

Yeah.

Isn’t that what I said?

Ian said:

Yeah.

Isn’t that what I said?

Well I’m allowed to agree with you

If Alan Stern and Mike Brown got into a fight, who would win?

A whole new world
Every turn a surprise
With New Horizons to pursue
Every moment red-letter
I’ll chase them anywhere
There’s time to spare
Let me share this whole new world with you.