Pluto

From the moment of its discovery, Pluto has been the focus of much debate and curiosity not to mention a large amount of head-scratching by scientists and astronomers attempting to make sense of this far off terrestrial object. Recently, Pluto has been downgraded, demoted from the position of “ninth planet” of our solar system to the dubious category of “dwarf planet.”

A Look at Pluto

In 1930 Clyde Tombaugh discovered Pluto, and part of the reason it was quantified as a planet from the jump lay with Tombaugh’s current project of the time—the search for a ninth planet. Of course even if Tombaugh has been about some other pursuit entirely, the discovery of Pluto would have been labelled the discovery of a planet due to the cap on astronomical knowledge of the time. Here was an object that ranked among the largest found in the solar system (taking satellites and plantismals into consideration) and had an orbit around the sun; certainly this was a planet. It even had satellites of its own, three moons to be named Charon, Nix and Hydra. Yet it was in these planet- defining features that much of the anomalies and curiosities were discovered; the orbit, the size, and the satellites of Pluto.

Pluto’s Controversies

From the very beginning Pluto was an object of controversy, starting with the naming of the object. Names were offered and rejected solely based on the popularity (and lack thereof) of the scientist making the offer. In the end it was an English schoolgirl named Venetia Burney, a fan of mythology as well as astronomy, who offered the name, and was awarded five pounds when it was accepted.

The orbit of Pluto was remarked upon for its differences in comparison to the other eight planets of the solar system. Rather than having an elliptical orbit that kept it “in its own lane” travelling around the sun, Pluto would cross orbits with Neptune, putting it at some parts of the orbit closer to the sun than Neptune itself. This oddity, a footnote in scientific textbooks, would later be pointed out as an early indicator that Pluto was not, in fact, a planet at all.

Pluto’s relationship with Charon also called its planetary status into question. As the barycentre, or centre of gravity of each body, lay above the surface of the object, they actually exist as a binary system rather than a planet with a satellite moon.

Once the Kuiper belt was discovered, along with the object Eris, Pluto’s status as a planet was doomed. Eris, began larger than Pluto, was considered a possible tenth planet, but the IAU, the body tasked with astrological naming, determined that it was not. Their reasons also left Pluto out of the loop, and so a new classification was created, dwarf planet (but a dwarf planet is not actually a planet at all.)

Pluto’s Makeup

Pluto is so far away that much of what we know about it is conjecture, but should be confirmed when the NASA expedition New Horizons reaches the dwarf planet in 2015. We believe that it is made up of a silicate and water ice core, with a water ice mantle and a frozen nitrogen crust.

The atmosphere of Pluto is also a bit of an oddity. When it is far from the sun, the atmosphere is frozen solid and lies on the ground. When it approaches the sun the frozen atmosphere begins to melt and evaporate, creating the slight gas atmosphere that surrounds the dwarf planet.

Final Thoughts New Horizons will answer a lot of questions we have about Pluto as well as Charon and other objects in the Kuiper belt. NASA has confirmed that some of the ashes of Pluto’s discoverer, Clyde Tombaugh, are on board New Horizons.