Date: April 1, 2010

Title: BREAKING NEWS! Pluto Regains Planet Status!


Podcaster: Patrick McQuillan

Organization: Incorporated Research Institutions for Seismology (IRIS): Music at the end of the podcast: How Many Planets? by They Might Be Giants

Description: Pluto is soon to regain its status as a full fledged planet, due to a little used rule in the bylaws of the International Astronomical Union. Learn how and when this world shattering change of events is going to take place. Pluto the planet is back!

Bio: Patrick McQuillan earned a B.S. degree in Physics from the College of William and Mary. His senior research project involved determining the period of variable stars, most notably Alpha Auriga. This was at a time when collecting data meant going to the roof of the physics building, locating the research star by hand, and tracking the star manually by following a guide star in the finder scope. No GPS-auto-guiding-from-a-climate-controlled-remote-location! In the twenty plus years since then, he has explained astronomy to the general public as a Planetarium Director, the Education Manager for Challenger Center for Space Science Education, a NASA Solar System Ambassador, and currently explains Earth Science as Education and Outreach Specialist for IRIS. You can view current earthquake activity using the Seismic Monitor located on the IRIS website.

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Patrick: Hello, I’m Patrick McQuillan, Education and Outreach Specialist with IRIS, the Incorporated Research Institutions for Seismology, a NASA Solar System Ambassador and a former Planetarium Director. Welcome to the April 1st edition of the 365 Days of Astronomy Podcasts.

This may be a first for the 365 Days of Astronomy Podcasts. We are able to bring you breaking astronomy news before any of the major news outlets have had a chance to report on this exciting topic. On April 12 through 16, approximately 500 astronomers and space scientists will gather at the University of Glasgow for the Royal Astronomical Society’s National Astronomy Meeting. This is the United Kingdom’s largest professional astronomy conference. An advance press release that details important activities to occur during the conference, includes a short note about the submission of a referendum concerning Pluto that will be officially presented to the International Astronomical Union.

You will remember that in 2006, the International Astronomical Union, the official world organization with the responsibility for naming astronomical objects, formed a Planet Definition Committee. The job of the committee members was to craft an official definition of the word planet. The definition that was approved was worded such that Pluto no longer qualified as a planet and so Pluto was demoted to dwarf planet status.
Well, only about 350 of the 9,000 professional astronomers who are members of the International Astronomical Union actually participated in the planet definition vote that resulted in Pluto’s demotion. This is only 4% of the eligible voters. This is far from a majority and not even close to a quorum.

Ok, so here is the exciting breaking news part of our April 1 Podcast. According to an obscure and little used rule in the bylaws of the International Astronomical Union, any vote that is passed by less than a majority of voting members can be overturned by submission of a referendum signed by more professional astronomers than those that originally voted. The referendum must be presented at an official annual meeting of a recognized professional astronomical organization.

Since over 500 professional astronomers will attend the Glasgow meeting this month, they have enough signatures to overturn the International Astronomical Union’s current definition of planet. Professional astronomers will revert to the original definition and Pluto will once again officially be a planet. Yeah Pluto!
All they have to do is present the referendum during the meeting. So it is pretty much a done deal. So be prepared to hear about Pluto on every news station on the Earth for the next few weeks. By the way, the Earth was considered a planet under both definitions. Yeah Us!

Additionally, any vote of the International Astronomical Union that is overturned by a referendum can only be reexamined and passed by a majority of members. This would require over 4500 astronomers to vote to demote Pluto, a very hard task indeed. So the Planet definition that allows Pluto to be a planet is very likely going to be with us for a long time.

Pluto itself has been with us for a long time. The search for the object that became known as Pluto began with Percival Lowell in 1905. Lowell was convinced that a error in the predicted locations of the planets Uranus and Neptune was due to the pull of gravity from an undiscovered Planet X. X in this case stands for unknown, not the Roman numeral for the number 10.

Between 1905 and 1907, Lowell used a camera with a 5 inch aperture to take photographs of the area of the sky he suspected that the unseen planet would be located. Unfortunately, Pluto was outside the search location AND too faint to be recorded with the instrument at hand.

He tried again in 1911 with no success.

In 1914, Lowell borrowed a 9-inch camera from Swarthmore College. Over the next two years nearly 1,000 photographic plates were taken. They covered a large area of the night sky.

In order to detect the suspected planet, two photos must be taken of the exact part of the night sky. The photos are taken several nights apart. The two photos are then placed in a Blink-Comparator. A Blink-Comparator is kind of like a large pair of binoculars. Flipping a switch will allow the viewer to see first one photo, then the other. The two photos are ‘blinked” back and forth rapidly while the viewer looks for any dot that has moved in location from one photo to the other. It is long, difficult, tedious work.

It is especially difficult if the area of the photos contains any of the Milky Way. In those photos there can be over 400,000 stars per photo.

Planet X was not discovered.

In 1916, Lowell died suddenly of a stroke and no additional planet searching was done for the next 13 years.
In 1928, a 23 year old Kansas man sent some drawings of Jupiter and Mars that he made using a 9 inch telescope he constructed to V. M. Slipher, the current director of Lowell’s Observatory. Slipher was so impressed that he invited young Clyde Tombaugh to join the staff of the Observatory on a three-month trial basis.

Tombaugh would use the new 13-inch Alvin Clark telescope to search for Planet X. Tombaugh took the photos and Slipher blinked the plates.

After two weeks of quick blinking, Slipher gave up, defeated by the shear number of stars on each plate. He turned the job of searching the plates over to Tombaugh.

From June 1929 until February 1930, Tombaugh searched plate after plate with no luck. Then on February 18, 1930, he detected a dot that moved the correct amount…it was the elusive Planet X.

Ironically, it was later discovered that Pluto was photographed on two plates of the 1000 that Percival Lowell had taken in 1915. Lowell missed his chance. Of course, once you know the exact location of an astronomical object, it is much easier to go back and look to see if you missed it. Even in astronomy, hindsight is 20/20.

After the new planet was discovered, Constance Lowell, Percival’s widow, wanted to name the new planet “Lowell”. She soon changed her mind and wanted to name the planet “Constance”. Fortunately for us, V. M. Slipher chose to ignore her.

Tombaugh’s favorite name for the new planet was Pluto. The name Pluto was suggested by 11-year old Venetia Burney of Oxford, England. She was interested in astronomy and classical mythology, and considered the name of the Roman god of the underworld fitting for a presumably dark and cold world.

Just for the record, the Disney character Pluto, introduced in 1930, was named in honor of the astronomical body. Mrs. Lowell reluctantly admitted that Pluto was a fine choice since the first two letters, P and L, were the initials of Percival Lowell. There is no record of what she thought the “uto” stood for.

Almost immediately, Pluto’s faintness and lack of a resolvable disk in large telescopes cast doubt on the idea that it was Lowell’s Planet X. An accurate estimate of Pluto’s mass was not possible until the discovery of Pluto’s largest moon Charon in 1978. Pluto has three known moons. Pluto’s small mass, calculated to be about 0.2 percent that of the Earth, was far too small to account for the errors in Uranus’ predicted position.
In 1992, data from the Voyager 2 spacecraft’s flyby of Neptune was used to calculate a more accurate value for Neptune’s mass. This revised Neptune’s mass down 0.5 percent. Using Neptune’s new mass, the errors in Uranus’ position and the need for a Planet X vanished.

Astronomers have known from the beginning that Pluto was a misfit.

It is tiny. It is actually smaller than seven of the solar system’s moons: the Earth’s Moon, Io, Europa, Ganymede, Callisto, Titan and Triton.

It has a weird orbit. Its orbit is tilted 17 degrees to the plane of the solar system. It crosses inside the orbit of Neptune for part of its journey around the Sun. So sometimes Pluto is the 8th planet from the Sun.
Even so, Pluto’s status as a planet was never seriously questioned until 1992. That is when members of a belt of icy bodies began to be discovered. This group of objects is known as the Kuiper belt. Over 1000 Kuiper Belt Objects have been discovered and it is estimated that over 70,000 objects with a diameter of 100 km may exist.

Well, the real trouble came in 2005 when Caltech astronomer Mike Brown and colleagues found a Kuiper Belt Object that was larger than Pluto. So, if Pluto was a planet, then this object must be a planet too.
Ok, no problem. Except that there might be dozens of worlds larger than Pluto in the Kuiper belt. Should they all be considered planets? Do we need that many planets?

Some astronomers said “the more the merrier.” Others disagreed. They felt that Kuiper Belt Objects are a different sort of thing, and should be in their own class. Others were just confused.

So this is where the International Astronomical Union gets involved. They decided that professional astronomers, and the rest of the world, needed a better definition of the word planet.

They proposed, and voted to approve the following definition:

A planet is a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (c) has cleared the neighborhood around its orbit.

Uhm..yeah…even more confusing. But basically this translates into: to be a planet, a world must have enough gravity and mass to gather itself into a ball; it must orbit the Sun; and it must have cleared its orbit of all other competing bodies.

Which means that Pluto gets dropped from the planet team since its neighborhood is not cleared of competing bodies ‘cause of all those Kuiper Belt Objects that are hanging around.

So the asteroid Ceres, which orbits the Sun and is a ball shape, would not be a planet because it orbits in the cluttered asteroid belt.

Problem solved. Or was it? I mean just think about Pluto, the non-planet’s orbit. Pluto’s orbit crosses Neptune’s orbit. So you could say that Neptune hasn’t cleared the neighborhood around its orbit. So Neptune is not a planet! Now we are down to seven planets.

If you continue this logic to the extreme, you will soon end up with zero planets in the solar system. No planet has completely cleared its neighborhood of asteroids and comets. Not even the Earth. The dinosaurs could verify that fact.

So the awkward new definition of planet, coupled with the very low number of professional astronomers has led many astronomers to call for a recount.

Luckily, given the obscure workings of organizational bylaws, Pluto will soon be a full member of the elite Planet Class of nine.

In anticipation of the passing of the referendum later in the month, people’s reactions were gauged.
NASA was happy that their New Horizons planet probe was again en-route to a full fledged planet and not a common dwarf planet.


Neil deGrasse Tyson, director of New York City’s Hayden Planetarium is quoted as saying, “In our exhibits, we abandoned the word planet as a useful word completely. We don’t organize by planet status. We organize by what objects look like compared to what other objects look like.” So in Neil’s world, you have four rocky objects close to the Sun, a bunch of asteroids, then four large gaseous objects and then a bunch of icy objects beyond them.

A well-known 6-year old (well known in my house at least) exclaimed, “Yeah! It’s very good. Yeah! Yeah! Pluto’s being a planet. Yeah! Yeah! Yeah! Yeaha…Yeaha…Yeah…Yeah! Yeah!

A famous 8-year old philosophically stated, “I don’t think Pluto cares if we call it a planet or not a planet. It still goes around the Sun as it always did.”

A very attractive mom pondered, “I don’t know like what all the fuss is about. I mean really what difference does it make? How can you change the status of something like a dog? A dog is a dog. What are you going to tell Mickey?”

So there you have it, emotions are running the gamut from incredible excitement to wondering why it is even a problem. Well enjoy Pluto’s status change back to planet. This is a story we could only bring you today on the April 1 365 Days of Astronomy Podcast.

End of podcast:

365 Days of Astronomy
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