Pluto

TO BE OR NOT TO BE, PLUTO

Ever since Pluto was discovered in the early twentieth century, there has been controversy over its status as a major planet. Technology was extremely limited compared to what is available today. It was by tracking the larger planets and using Newtonian physics, that Pluto was found. Pluto's position was estimated by calculating its gravitational effects on the orbits of the other planets. Through these calculations, Pluto was estimated to be a certain mass and be within a certain area. This area was then searched relentlessly using Earth based telescopes. Early in astronomy, moving objects in space was found by comparing two images taken a period of time apart. Differences within the two images represent a moving object against a background of distant nonmoving stars. So when Pluto was found, it was nothing more than a pinpoint of light on a plate negative. At the time it was only through observations from Earth and an educated guess, did we speculate what Pluto is or is not. Now almost a century later, with more advanced technology we have learned much more about our solar system and Pluto. With a better understanding of how our solar system was formed and the recent discovery of other Pluto-like objects in space, many feel that Pluto is not a planet at all. There is even speculation of objects larger than Pluto to be discovered!

Using basic knowledge of physics and the orbital motion of the eight planets, a ninth planet was thought to exist. Its location was calculated and in 1930, Clyde Tombaugh, an astronomer at Lowell Observatory in Flagstaff, Arizona (Stern, 18) discovered Pluto using his telescope. Tombaugh, on March 13, 1903 (Stern, 18) announced the finding of the ninth planet, Pluto. Looking through any telescope on Earth, Pluto looks like a dim star, nothing more than a speck in the sky. With its extreme distance, even the large orbiting Hubble Space Telescope fails to resolve any of Pluto's features. On Earth, better telescopes allowed astronomers James Christy and Robert Harrington to announce the discovery of Charon, Pluto's satellite, in 1978 (Miller, 176). Estimated to be 1,200 kilometers, this satellite was almost half the size of Pluto. Further studies by astronomers, using various techniques and instruments, determined other aspects of the mysterious planet and moon. It was found that Pluto takes 250 years to make a single orbit around the sun. A highly irregular elliptical orbit, takes the planet as close to 30 AU (1 AU is the distance from the sun to the Earth) and as far as 50 AU from the sun (Stern, 127). Its orbit is also angled in comparison to the orbital plane of the other eight planets. Pluto rises 8 AU above and drops 13 AU below this plane (Stern, 127). Further studies did suggest that Pluto has an atmosphere but this is highly speculative (Stern, 391-430) and possible frost deposits (Stern, 460-468). As for Pluto's evolution, it has been theorized that Pluto was originally a moon of Neptune and had its trajectory changed due to a collision with another body and its final orbit resulted from further interactions with the object, which we now call Charon (Stern, 606-608). Pluto could also be a captured asteroid from a distant star. Regardless of how Pluto came to be, its evolution is much different in comparison to the other major planets in the solar system.

Nebulas, large expanses of gas and dust, created stars like our own. The star or the solar system was created through a gravitational pull towards a defined point or area. The point would gain mass and become increasingly denser, more massive, increasing the gravitational pull, attracting more dust and more gas, causing a run away effect. As the gases and dust are compressed towards the center, the Law of Conservation of Momentum creates a spinning motion causing the gas and particles to form into a disc shape. It is within this disc that the planets are formed. Over time, the central point becomes increasingly dense; increasing pressures causes heat, heating the center to the point for the heat to be extreme enough to start a nuclear fusion reaction. As the sun ignites, the surrounding gases and dust gets blown away leaving some of the larger objects behind. These large objects will further form to create the inner rocky planets with a higher density, and leaving the gases to form the outer gas giants. The solar system as we see it today, was formed from these objects as they spun around the sun. Debris collects and form clumps due to magnetic forces. A televised event has shown astronauts observing objects forming clumps in space. The larger clumps collect smaller clumps, continuously growing a larger and larger mass that gravity compresses into a round planet. This is the same process that created the sun except the planets do not ignite because there is not enough mass to generate the kind of heat and pressure needed for fusion. Not all objects become planets. Other objects, either through some coincidence or a collision with other bodies creates moons. Some moons are formed similar to how planets formed around the sun, while others are captured asteroids. Our eight of the planets are assumed to have formed in this manner and that's is why our planets orbit the sun in a single plane. Pluto is thought to be a stray object caught by gravitational forces of the sun because of its unusual orbit. Pluto's orbits at an angle going above and below the plane of the other planets orbits.

When Pluto is compared to our major planets, it is difficult to see why it was named a planet at all. Its birth is unlike how the major planets in our solar system were formed. The key is its unusual orbit. Even if its orbit was within the solar plane and was somehow knocked out of place by some event, would such occurrence be more likely with the larger inner planets? Yet, they remain in their unique orbits around the sun. Pluto was not created like a planet and should not be a planet for this reason alone. Further analysis of Pluto's composition could provide answers, however, there is limited knowledge in this area. We do know more about the other planets.

Planet Diameter km Gravity Composition / Atmosphere Temperature F

Mercury 4,880 0.38 Nickel-iron, silicates -279 to 441

Venus 12,100 0.91 Nickel-iron, silicates / CO2 860

Earth 12,756 1.0 Nickel-iron, silicates / NO -127 to 136

Mars 6,786 0.38 Silicates, iron / CO2 -220 to 68

Jupiter 142,984 2.3 Hydrogen