When I was a kid, whenever we had to go on long trips, one of my more annoying habits - at least as far as my parents were concerned - was to constantly ask "how far!?" If I were riding the cold depths of space in the backseat of New Horizons probe to Pluto, the answer would be a definitive "halfway there!"
New Horizons is the NASA probe to have a closer look at one of the more distant specks of light in our solar system, Pluto. Of course, when it was launched in January 2006, Pluto was still considered a "planet." Since then, it has been "demoted" in a sense. It's now a "minor planet" or "plutoid," simply one of the larger (but not the largest, that honour currently belongs to a more distant speck called "Eris") objects at the edge of our solar system.
Actually, by tremendous coincidence, NOVA on PBS recently showed The Pluto Files with Neil DeGrasse Tyson. Tyson is the director of New York's Hayden Planetarium who got into a bit of trouble with school children everywhere when, after a renovation of the planetarium, the new solar system display did not include Pluto as one of the main planets.
I missed half of the original airing, however, it can be watched online at http://video.pbs.org/video/1425502261/. It was quite the lighthearted take on what was actually a bit of a contentious debate. After some thought, I have to agree to a certain degree that the reasoning is sound. Still, in my heart, Pluto will always be a planet. It's not a scientific view. But it's an honest one.
Clyde Tombaugh discovered this little body on the edge of the solar system. Tombaugh himself started off observing the planets with a home-built telescope from the family farm in Kansas. His drawings led him to the attention of Lowell Observatory, where he was hired. During his time there, he was brought on to a project to hunt for the "10th Planet."
In January of 1930, Lowell took two photographs of a section of sky in Gemini and compared them. And there, a tiny dot flipped back and forth. After a few follow-up observations, it was announced that the 10th planet was found. To this day, he continues to be deservedly honoured by his home town of Streator, Illinois. Some of his ashes are even on their way to Pluto and beyond on the New Horizons probe.
However, things changed for Pluto starting in the 1990s. Dave Jewitt and Jane Luu discovered a small object out in that same region of the solar system called 1992 QB1. Over the course of the next several years, many more have been found including a couple such as Eris that are actually larger than Pluto.
This sparked a debate...can we actually call Pluto a "planet?" After all, it does have several characteristics we attribute to our classic examples of planethood - it's big, round, orbits the sun...the usual stuff. In 2006, the decision was made by the International Astronomical Union...Pluto was no longer a planet a "dwarf" planet.
So, in the meantime, we wait for 2015 when New Horizons which is the fastest moving object ever launched by humans encounters this mysterious object. It will likely bear a striking resemblance to such objects as Neptune's moon Triton. But it's always the unexpected that makes planetary science all the more interesting.
And we're halfway there!