Pluto’s Answering Machine

The first step to acceptance is surprise, the second denial, the third depression, and soon to come, anger.

Pluto has experienced denial, then anger, then bargaining, now depression. Hopefully soon will come acceptance.

Recently Pluto‘s been feeling a little blue due to his demotion to a dwarf planet. His buddy Eris is there to show him the brighter side.

Listen here [0:39m]:

What’s the facts:

Pluto was discovered in 1930 (accidentally) by Clyde W. Tombaugh in Arizona during a sky survey at the Lowell Observatory. It is composed primarily of rock and ice and is significantly smaller than the other 8 planets: approximately a fifth the mass of the Earth’s Moon and a third its volume. It is much smaller than any of the official planets and has been recently classified as a “dwarf planet“. This happened largely due to the resent discovery of a larger dwarf planet named Eris, by Dr. Michael Brown of the California Institute of Technology. Eris opened the possibility that there may be many bodies of similar size. Scientists decided voted to consider the planets’ differences in size, orbit, and location as a criteria for a new classification, with objects like Pluto and Eris belonging to a special category of Kuiper Belt objects referred to as dwarf planets (but there is clearly debate on that decision, see comment below!). Click here to learn more about Pluto’s new classification.

Original air date 23 June 2009.


36 responses to “Pluto’s Answering Machine

  1. “Scientists” did NOT decide that Pluto and Eris should be classified separately. Only four percent of the IAU voted on the controversial demotion, and most are not planetary scientists. Their decision was immediately opposed in a formal petition by hundreds of professional astronomers led by Dr. Alan Stern, Principal Investigator of NASA’s New Horizons mission to Pluto. One reason the IAU definition makes no sense is it says dwarf planets are not planets at all! That is like saying a grizzly bear is not a bear, and it is inconsistent with the use of the term “dwarf” in astronomy, where dwarf stars are still stars, and dwarf galaxies are still galaxies. Also, the IAU definition classifies objects solely by where they are while ignoring what they are. If Earth were in Pluto’s orbit, according to the IAU definition, it would not be a planet either. A definition that takes the same object and makes it a planet in one location and not a planet in another is essentially useless. Pluto is a planet because it is spherical, meaning it is large enough to be pulled into a round shape by its own gravity–a state known as hydrostatic equilibrium and characteristic of planets, not of shapeless asteroids held together by chemical bonds. These reasons are why many astronomers, lay people, and educators are either ignoring the demotion entirely or working to get it overturned.

    Dwarf planets are planets too! Counting them gives our solar system 13 planets: Mercury, Venus, Earth, Mars, Ceres, Jupiter, Saturn, Uranus, Neptune, Pluto, Haumea, Makemake, and Eris.

  2. Thanks Laurel for you very passionate response! It is good to highlight the fact that there is more than one opinion on this matter.

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  5. I need help!I have nothing to wear 4the vma’s lol i realy need help!I need 10 facts about Pluto!!!

  6. Hey Selena, how’s this (it all comes from the Pluto wikipedia page):

    (1) Pluto is the second largest dwarf planet after Eris
    (2) Pluto is the closest thing to a double planet in our Solar System, since Charon is just 1/7th the mass of Pluto
    (3) Pluto has 2 other moons, Nix & Hydra, found in 2005
    (4) Pluto has a thin atmosphere of nitrogen, methane and carbon monoxide that is only around when it is closest to the Sun
    (5) Pluto’s orbit is inclined 17 degrees relative the orbital planes of the other planets
    (6) Occasionally Pluto’s orbit takes it closer to the Sun than Neptune – it last did this between 1979 and 1999
    (7) Pluto was discovered in 1930 by Clyde Tombaugh, who was looking for a more massive planet that was thought to be perturbing the orbit of Neptune (it isn’t)
    (8) The New Horizon spacecraft will reach Pluto in 2015, carrying Clyde Tombaugh’s ashes (who died in 1997)
    (9) Pluto is now considered to be one of the largest members of the Kuiper Belt population, icy/rocky bodies that orbit at the edge of our Solar System
    (10) Because of its demotion, “pluto” is now a verb meaning “to demote or devalue someone or something” as in “I totally plutoed my car when I drove over the curb to fast”.

    Hope that helps!

  7. why is pluto not a planet?

    • A good question Natasha, particularly since Pluto was officially considered a planet until 2006! The main reason is that in the past few years astronomers have been finding other objects similar to Pluto in size and mass, and we were faced with the prospect of having 10, 20, maybe even hundreds of planets in the Solar System – imaging trying to remember the names of a 100 planets! Instead, the International Astronomical Union voted to create a new name for objects like Pluto, called “dwarf planets”, to indicate they were simply smaller versions of the “real” planets Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus & Neptune. This doesn’t mean Pluto itself has changed – all that’s changed is what we call it. This happened before in astronomy: the four biggest asteroids – Ceres, Pallas, Juno and Vesta – were all considered planets in the early 1800s, but as similar objects were found in large numbers these objects were reclassified as asteroids (Ceres is now a dwarf planet like Pluto – it’s been reclassified 3 times!). Also, not every astronomer is happy with this change; see some of the other comments on this page.

    BEst “Dwarf Planet EVEH”~

  9. it smells like absoloute egg ~&& itsss inhumainlyy discustinggg !!! :@

  10. There is another way of defining planets – normal visibility in small telescopes. Put a limit something like visual magnitude 14, which makes Pluto visible as a flickering light point in a reflector of at least 30 cm disk diameter. The other Kuiper Belt objects stay invisible, as they are farther out and most of them smaller. As for the asteroid belt between Mars and Jupiter, just take the 4 ones with best mean visibility as seen from the sun: (4)Vesta (that once was a molten sphere, badly damaged by en impact), (15)Eunomia (probably a big fraction of a larger body, showing a metal-rich composition on one side and a just stony surface characteristic on the other – and it shines just a little bit brighter than (3)Juno), (1)Ceres (neatly spherical) and (2)Pallas (also hold together in an almost spherical shape by its own gravitation). Then with the “recognised” 8 planets and adding Vesta, Eunomia, Ceres, Pallas and Pluto you get 13 planets. Ceres and Pallas are a kind of twins, as they orbit in almost the same mean distance from the sun though normally not near to each other.

  11. pluto is the smallest planet

  12. PLUTO ROCKS!!!!!!!!!!!!!!!!!!!!!!!

  13. is pluto still present in our solar system?

  14. why is pluto small


  16. i luv pluto

  17. Why is it even called Pluto? Even tho Pluto is small it is still a planet. This pic is cool.

    • Pluto was named after the Roman god Pluto, also know as the Greek Hades. Pluto, as god of the Underworld (and thus death), was feared but not loved, which is why the Romans did not name after one of the closer planets. By the time they discovered all the way out to Pluto, most of the other main gods (and quite a few minor ones) were already taken (Mercury ( know as Hermes), Venus (Aphrodite), Mars (Aries), Jupiter (Zeus), Saturn (Apollo), Uranus (The Hevens), Neptune (Poseidon), plus their moons, like Mars’ moons Phobos (Fear) and Deimos (Terror), or some of Saturns moons Iapetus (Titan of mortality, The Piercer), Dione (Titan of Oracles), and Rhea (Titan mother of Zeus, Hades, Poseidon, ect.). The Romans and Greeks were big on naming their planets after gods.

  18. I just want to know all of about PLUTO

  19. ok, so … is the Kuiperbelt a remanent of the making of this solar system, or is it all bits and parts from a planet (Pluto but than larger) that was hit by some large object ?
    i read somewhere that the Kuiperbelt is made of the same materials as Pluto.
    if Pluto was hit by some large object, it would also explain why its orbit is tilted .
    ah well … just a few thoughts 🙂

  20. pluto is still a planet in space i wish i could go their wonderfull picture like u so much

  21. I think we should keep pluto it is a beauty


  23. Just thought I would shed some light upon the subject here 🙂 There are many reasons for the decision to reclassfiy Pluto as a dwarf planet, so I thought I might try to list some of them for you.

    1. The ellipticity of its orbit i.e. how much of an oval Pluto’s orbit is. All of the major planets in the solar system exhibit very low ellipticities in their orbits (most are nearly circular). In this regard, Pluto is very different to the other planets. However this type of orbit is common amongst TNOs (Tran-Neptunian Objects) such as comets.

    2. The current definition of a planet is an object in orbit around a large primary object e.g. a star that has cleared its orbital path of all other major bodies. This does not mean that the planet must have moons (Mercury for example, does not). It does however mean that it must be the dominant body in its orbit so that in the formation of the planet, it acreted (collected) the other material within its vicinty. With every other planet in the solar system this is true. However, Pluto as several similar sized objects in its vicinty that it has not captured due to its low gravitational pull. I notice that someone has commented above that if the Earth were in the same orbit, it would also be classified as a dwarf planet. This is not true as with the Earth’s current mass, during its formation it would have cleared it’s orbital path due to gravitational attraction and therefore would be classified as a planet.

    3. The chemical composition of Pluto is very similar to other objects in the solar system such as comets and asteroids. In fact the accidental discovery of Pluto was due to the makeup of its surface. Pluto is largely composed of ice and therefore is very reflective, allowing it to be seen in telescopes whereas similarly sized objects may not. This composition also means it fails to fall into the two current planetary types: terrestrial planets (small rocky bodies, close to the Sun) and jovian planets (large, gaseous objects further from the Sun).

    I am fully aware that there are many different opinions on this topic and merely wished to share what I know about planetary classification courtesy of my Astrophysics degree.

    Hope this helps 🙂

  24. pluto is a gas giant still a planet but a drawf planet so it is a PLANET!!

  25. There are several misconceptions in the last two comments.

    First, Pluto is not a gas giant. It has a solid surface, which gas giants do not have, and its composition is much more like that of terrestrial planets than like that of gas giants.

    Second, having an elliptical orbit does not preclude an object from being a planet. Mercury’s orbit is nearly as elliptical as is Pluto’s. Giant exoplanets found in other solar systems have extremely elliptical orbits. Some of these objects are bigger and more massive than Jupiter. Does having elliptical orbits make them not planets?

    Pluto’s orbit is nothing like that of a comet. Comets have extremely elliptical orbits that take them from the Oort Cloud or Kuiper Belt into the inner solar system and back again. Pluto never comes anywhere near the inner solar system. Interestingly, a giant exoplanet has been found in another solar system that actually does have a comet-like orbit around its star. However, that does not make this massive object a comet. Jupiter has a composition very similar to the Sun, but that does not make it a star.

    The so-called “current definition” of a planet is nothing but one point of view in an ongoing debate. It is not some sort of gospel truth. Many professional astronomers do not accept it and believe the criterion that an object must “clear its orbit” to be a planet is unnecessary and problematic. The calculations have been done by several astronomers as to whether Earth, with its current mass, would “clear its orbit” if it were in Pluto’s orbit, and the answer they came up with is it definitely would not. The issue is not the mass of the Earth but the fact that the farther an object is from the Sun (or its parent star), the larger an orbit it will have to clear. Earth would not be able to clear Pluto’s large orbital field of Kuiper Belt Objects. Herein is the major problem with the IAU definition. The same object can be a planet in one location and not a planet in another. In contrast, a good definition must take into account both where an object is and what it is.

    Pluto is not largely composed of ice. It is estimated to be 75 percent rock and geologically differentiated into core, mantle, and crust, just like the Earth. It is covered by a layer of ice, but that does not make up the majority of its composition.

    Also, why assume there are only two planetary types–terrestrial and jovian? That is part of the problem. The reality is, there likely are many types of planets, and dwarf planets are a third planetary type. They are planets because they are large enough to be in hydrostatic equilibrium but of the dwarf subcategory because they are not large enough to gravitationally dominate their orbits. 🙂

  26. hi,
    my daughter was looking for pictures from PLUTO for en english report on planet of our solar system..
    she found this marvelous picture but there is non explanation about it…and we wonder….
    could anyone tell us bout it?
    caroline (mother from anastasia) France

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  28. i love how pluto looks

  29. i hate it

  30. oh my god!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

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