WEBVTT - Is Pluto Really Not a Planet?

0:00:01.840 --> 0:00:07.520
<v Speaker 1>Welcome to Brainstuff, a production of iHeartRadio, Hey brain Stuff

0:00:07.600 --> 0:00:12.119
<v Speaker 1>Lauren Vogelbaum here. Back in two thousand and six, to

0:00:12.160 --> 0:00:15.120
<v Speaker 1>the puzzlement of many in the non scientific public and

0:00:15.320 --> 0:00:19.960
<v Speaker 1>some astronomers as well, the International Astronomical Union decided to

0:00:20.120 --> 0:00:24.639
<v Speaker 1>demote Pluto from its status as a full fledged planet. Instead,

0:00:24.800 --> 0:00:28.479
<v Speaker 1>the IAU decided what had been considered the most distant

0:00:28.520 --> 0:00:31.440
<v Speaker 1>of the nine planets in our Solar System actually belonged

0:00:31.480 --> 0:00:35.920
<v Speaker 1>in a new category of dwarf planets. This category also

0:00:35.920 --> 0:00:39.120
<v Speaker 1>includes Series, the largest object in the asteroid belt between

0:00:39.200 --> 0:00:44.760
<v Speaker 1>Mars and Jupiter. The IAU's reasoning was that Pluto only

0:00:44.840 --> 0:00:47.600
<v Speaker 1>had two of what they had decided were the three

0:00:47.720 --> 0:00:51.160
<v Speaker 1>characteristics of a planet. That it is in orbit around

0:00:51.200 --> 0:00:54.080
<v Speaker 1>the Sun, that it has sufficient mass for its self

0:00:54.080 --> 0:00:57.360
<v Speaker 1>gravity to overcome rigid body forces and give it a

0:00:57.480 --> 0:01:01.600
<v Speaker 1>nearly spherical shape. And that it has cleared the neighborhood

0:01:01.680 --> 0:01:04.560
<v Speaker 1>around its orbit of other objects, a meaning that it's

0:01:04.600 --> 0:01:09.000
<v Speaker 1>either collided with, captured, or driven away smaller objects nearby.

0:01:10.520 --> 0:01:13.840
<v Speaker 1>Pluto flunked that last test because it shares its orbit

0:01:13.880 --> 0:01:17.000
<v Speaker 1>with the Kuiper Belt, a sort of doughnut shaped disc

0:01:17.080 --> 0:01:21.080
<v Speaker 1>of thousands of smaller icy objects beyond Neptune that Pluto

0:01:21.200 --> 0:01:27.240
<v Speaker 1>has failed to clean up gravitationally speaking, the ii used decision,

0:01:27.319 --> 0:01:29.840
<v Speaker 1>which was voted on by a very small percentage of

0:01:29.880 --> 0:01:35.240
<v Speaker 1>the world's astronomers and planetary scientists, was a controversial one.

0:01:35.280 --> 0:01:39.160
<v Speaker 1>After a debate in twenty fourteen among scientists sponsored by

0:01:39.160 --> 0:01:43.000
<v Speaker 1>the Harvard Smithsonian Center for Astrophysics, the majority of the

0:01:43.120 --> 0:01:47.039
<v Speaker 1>non expert audience voted for a simpler definition of planet,

0:01:47.960 --> 0:01:51.000
<v Speaker 1>basically that it has to be spherical, an orbit around

0:01:51.000 --> 0:01:55.520
<v Speaker 1>a star or the remnants of one. This definition included Pluto,

0:01:57.400 --> 0:02:00.320
<v Speaker 1>and that audience aren't the only people who feel this way.

0:02:01.280 --> 0:02:04.120
<v Speaker 1>In a paper published in the journal Icarus in February

0:02:04.160 --> 0:02:08.200
<v Speaker 1>of twenty nineteen, a team of planetary scientists analyzed more

0:02:08.240 --> 0:02:11.600
<v Speaker 1>than two centuries worth of scientific studies and found that,

0:02:11.880 --> 0:02:14.560
<v Speaker 1>with the exception of one paper published in eighteen oh

0:02:14.560 --> 0:02:18.640
<v Speaker 1>two by British astronomer Sir William Herschel, nobody talked about

0:02:18.720 --> 0:02:21.640
<v Speaker 1>the non sharing of an orbit as a criterion for

0:02:21.720 --> 0:02:27.079
<v Speaker 1>distinguishing planets from non planets. To the contrary, the researchers

0:02:27.120 --> 0:02:30.360
<v Speaker 1>found that scientists routinely described what we now know to

0:02:30.360 --> 0:02:34.720
<v Speaker 1>be asteroids as planets until the nineteen fifties, because that

0:02:34.880 --> 0:02:37.840
<v Speaker 1>is when our instruments became sensitive enough to show that

0:02:37.919 --> 0:02:43.000
<v Speaker 1>asteroids had geophysical differences, namely, they weren't massive enough to

0:02:43.080 --> 0:02:48.959
<v Speaker 1>be rounded. The researchers wrote in the paper, We therefore

0:02:49.040 --> 0:02:52.760
<v Speaker 1>conclude that the argument made during the IAU planet definition

0:02:52.880 --> 0:02:56.840
<v Speaker 1>controversy that planet sized Kuiper Belt objects should be classified

0:02:56.880 --> 0:03:00.800
<v Speaker 1>as non planets because they share orbits is arbit and

0:03:00.919 --> 0:03:05.840
<v Speaker 1>not based on historical precedent before the article. This episode

0:03:05.880 --> 0:03:08.240
<v Speaker 1>is based on how stuff Works. Spoke via email with

0:03:08.320 --> 0:03:11.679
<v Speaker 1>paper co author Philip Metzger, a planetary scientist at the

0:03:11.760 --> 0:03:16.120
<v Speaker 1>University of Central Florida. He explained that the ia used

0:03:16.120 --> 0:03:20.880
<v Speaker 1>emotion of Pluto largely has been disregarded by planetary scientists.

0:03:21.520 --> 0:03:25.480
<v Speaker 1>A quote in science, we classify objects in ways that

0:03:25.560 --> 0:03:29.800
<v Speaker 1>are scientifically useful. The definition that says Pluto is not

0:03:29.880 --> 0:03:33.320
<v Speaker 1>a planet is not useful because scientists are not using

0:03:33.320 --> 0:03:36.600
<v Speaker 1>it in their publications. But the definition that has existed

0:03:36.640 --> 0:03:39.960
<v Speaker 1>since the time of Galileo, the one that most planetary

0:03:40.000 --> 0:03:43.520
<v Speaker 1>scientists actually use, is very useful, and we use it

0:03:43.560 --> 0:03:47.800
<v Speaker 1>in our publications all the time. That definition from Galileo

0:03:47.960 --> 0:03:51.400
<v Speaker 1>says that the planet is a geologically complex body like

0:03:51.480 --> 0:03:56.160
<v Speaker 1>the Earth is. Pluto is most definitely a geologically complex body,

0:03:56.560 --> 0:04:00.280
<v Speaker 1>fully worthy of the term planet, as Galileo and Planeto Harry,

0:04:00.280 --> 0:04:06.000
<v Speaker 1>scientists have used the word for the past five hundred years. Moreover,

0:04:06.120 --> 0:04:09.680
<v Speaker 1>Metzger argues the IAU's definition of a planet actually was

0:04:09.720 --> 0:04:12.960
<v Speaker 1>a step backward toward a pre scientific view of nature.

0:04:14.120 --> 0:04:18.400
<v Speaker 1>He said, scientists discovered the solar system is messy, that

0:04:18.560 --> 0:04:21.640
<v Speaker 1>planets don't all orbit the Sun, that they kick each

0:04:21.640 --> 0:04:25.320
<v Speaker 1>other around and share orbits with other objects. The IAU

0:04:25.360 --> 0:04:28.800
<v Speaker 1>definition tries to emphasize the organization of a solar system,

0:04:29.160 --> 0:04:32.279
<v Speaker 1>saying planets are the small number of objects that rule

0:04:32.400 --> 0:04:36.560
<v Speaker 1>in their orbits. It communicates the wrong idea that organization

0:04:36.800 --> 0:04:40.240
<v Speaker 1>is the central truth about solar systems. In fact, for

0:04:40.279 --> 0:04:44.200
<v Speaker 1>a planet to clear its orbit, the process is contingent, incomplete,

0:04:44.400 --> 0:04:50.479
<v Speaker 1>and often temporary. A broadening or rebroadening the definition of

0:04:50.480 --> 0:04:54.320
<v Speaker 1>planets would lead the way to including other objects like Aris,

0:04:54.360 --> 0:04:56.680
<v Speaker 1>an object in the Kuiper Belt that's twenty five percent

0:04:56.760 --> 0:05:00.200
<v Speaker 1>larger than Pluto. It was discovered in two thousand in

0:05:00.279 --> 0:05:04.160
<v Speaker 1>five and prompted the debate that led to the IAU's redefinition.

0:05:05.839 --> 0:05:08.680
<v Speaker 1>A Metzker said a problem with the two thousand and

0:05:08.680 --> 0:05:11.359
<v Speaker 1>six definition is that people have lost interest in the

0:05:11.360 --> 0:05:15.359
<v Speaker 1>discovery of planets. People think, well, they are just leftover

0:05:15.520 --> 0:05:19.320
<v Speaker 1>junk like asteroids, though they're not important. As a result,

0:05:19.400 --> 0:05:22.039
<v Speaker 1>the excitement is not taught in the classroom and the

0:05:22.040 --> 0:05:26.400
<v Speaker 1>public doesn't pay attention. But they are actually amazing planets

0:05:26.440 --> 0:05:29.159
<v Speaker 1>like Pluto and Shareon, and there are over one hundred

0:05:29.160 --> 0:05:34.200
<v Speaker 1>and fifty of them, and there is plenty that's interesting

0:05:34.240 --> 0:05:38.080
<v Speaker 1>about Pluto. How stuffworks also spoke via email with paper

0:05:38.080 --> 0:05:42.200
<v Speaker 1>co author Kirby Runyan, a planetary geomorphologist at the Planetary

0:05:42.240 --> 0:05:47.240
<v Speaker 1>Science Institute. He said Pluto has glaciers sliding down from

0:05:47.279 --> 0:05:51.240
<v Speaker 1>the mountains. It has a multi layered atmosphere with climate cycles.

0:05:51.560 --> 0:05:53.839
<v Speaker 1>It has mountains as big as the Rocky Mountains and

0:05:53.880 --> 0:05:57.080
<v Speaker 1>they are currently being built up. It has an ancient

0:05:57.120 --> 0:06:00.120
<v Speaker 1>ice lake with a shoreline. It has sublimation pits in

0:06:00.160 --> 0:06:04.200
<v Speaker 1>the ice with fantastical patterns that suggest convection is happening

0:06:04.320 --> 0:06:08.240
<v Speaker 1>under the ice. There's evidence of an underground ocean. There

0:06:08.320 --> 0:06:10.880
<v Speaker 1>must be a heat source to keep that ocean liquid.

0:06:11.360 --> 0:06:14.760
<v Speaker 1>There's even a possibility that life could exist in that ocean.

0:06:17.839 --> 0:06:21.200
<v Speaker 1>There's still much to be learned about Pluto. The probe

0:06:21.240 --> 0:06:23.839
<v Speaker 1>New Horizons did a fly by in twenty fifteen, but

0:06:24.000 --> 0:06:27.400
<v Speaker 1>most of Pluto's southern hemisphere was shrouded in winter darkness

0:06:27.440 --> 0:06:30.600
<v Speaker 1>at the time, and other regions were in low resolution,

0:06:31.640 --> 0:06:34.960
<v Speaker 1>and the probe didn't include every possible piece of equipment.

0:06:35.520 --> 0:06:39.480
<v Speaker 1>For example, if there is or was a subsurface liquid ocean,

0:06:40.000 --> 0:06:43.080
<v Speaker 1>discovering a magnetic field around the planet would provide a

0:06:43.160 --> 0:06:46.479
<v Speaker 1>solid clue, but would need to send a magnetometer on

0:06:46.520 --> 0:06:51.360
<v Speaker 1>our next spacecraft to head that way. Beyond that, it's

0:06:51.440 --> 0:06:55.640
<v Speaker 1>not known whether Pluto's features are unusual or representative of

0:06:55.720 --> 0:07:00.400
<v Speaker 1>other small planets, Iranian said. For instance, are our most

0:07:00.480 --> 0:07:03.680
<v Speaker 1>Huper Belt planets simple with just craters and fractures like

0:07:03.720 --> 0:07:07.039
<v Speaker 1>the moons of Uranus or share On, or are they

0:07:07.200 --> 0:07:10.600
<v Speaker 1>dynamic planets. Triton, we think, used to be a Kuiper

0:07:10.600 --> 0:07:13.680
<v Speaker 1>Belt planet and is now a satellite planet orbiting Neptune.

0:07:14.160 --> 0:07:18.000
<v Speaker 1>It also has rich and varied act of geology, like geysers,

0:07:18.160 --> 0:07:23.040
<v Speaker 1>but of a different nature than Pluto. However, Metzger is

0:07:23.120 --> 0:07:26.800
<v Speaker 1>not hopeful that the IAU will reconsider its decision. He

0:07:26.920 --> 0:07:30.240
<v Speaker 1>said many of its members have become stubborn about it.

0:07:30.800 --> 0:07:33.480
<v Speaker 1>This is why we aren't supposed to vote in science.

0:07:33.960 --> 0:07:38.680
<v Speaker 1>Voting creates biases. Taxonomical classification is a part of science,

0:07:38.880 --> 0:07:42.240
<v Speaker 1>so we should not allow biases to enter in. That

0:07:42.440 --> 0:07:44.360
<v Speaker 1>is why it was a mistake to vote on the

0:07:44.360 --> 0:07:53.080
<v Speaker 1>definition of a planet. It should have never happened. Today's

0:07:53.080 --> 0:07:56.040
<v Speaker 1>episode is based on article Pluto is it a planet?

0:07:56.080 --> 0:07:59.400
<v Speaker 1>After all? On how stuffworks dot Com? Written by Patrick J. Kiger.

0:08:00.080 --> 0:08:02.320
<v Speaker 1>And Stuff is production of iHeartRadio in partnership with how

0:08:02.320 --> 0:08:05.200
<v Speaker 1>stuffworks dot Com and is produced by Tyler Klang. Four

0:08:05.240 --> 0:08:09.080
<v Speaker 1>more podcasts my heart Radio, visit the iHeartRadio app, Apple Podcasts,

0:08:09.200 --> 0:08:11.120
<v Speaker 1>or wherever you listen to your favorite shows.