Pluto used to be a distant, mysterious, and unknown world. Discovered in 1930 by Clyde Tombaugh, Pluto begun as a full-pledged planet, but its unusual characters led scientists to question its planetary title. This led to its reassessment by the International Astronomical Union in 2006, where Pluto was degraded to dwarf planet status. But, after an unimaginably lengthy journey of nine years and 3 billion miles (4.8 billon kilometers), NASA's unmanned New Horizons spacecraft finally reached the dwarf planet Pluto for its long-awaited flyby, quickly turning it into a fascinating new world.
Scientists and engineers worked very hard to make Pluto's flyby a reality, and from that dream came the New Horizons' spacecraft. Every little detail of the journey had to be planned in order to ensure the spacecraft's success in reaching Pluto, and the journey was indeed quite spectacular. The spacecraft had to travel across dangerous sectors of our solar system, including asteroid belts. It even used Jupiter's gravity to increase it's own speed at one point. The following informational graphic depicts New Horizons' own structure and its journey in full detail:
Upon reaching Pluto, New Horizons captured the following beautiful, hi-res image of Pluto during the flyby:
Ultimately, though, scientists were most interested in learning more about Pluto and its moons. And they've acquired quite a lot of data from the spacecraft. Here are five of the most fascinating facts we have learned about Pluto during its flyby:
1. Pluto is larger than we thought
Because of Pluto's thin atmosphere, giving the planet a hazy edge rather than a hard one when viewed through a microscope, it was always very difficult to measure its size. However, New Horizons' flyby allowed scientists to accurately determine Pluto as having a diameter of 1,473 miles (2,370 kilometers), about 44 miles (70 kilometers) larger than we originally thought. This, in fact, makes it the biggest object in the Kuiper Belt, a region of the solar system beyond the orbit of Neptune, believed to contain many comets, asteroids, and other small bodies made largely of ice. Previously, it was difficult to determine whether Pluto was smaller or larger than its "cousin" Eris, but the new data from New Horizons show that Pluto is ever so slightly larger but less massive than Eris.
2. Pluto has ice caps and it might even snow there
There were theories that Pluto had ice caps, but nothing was certain until now. New Horizons confirmed the existence of ice caps and revealed their chemical composition: nitrogen ice and frozen methane. In addition, Pluto's surface temperature ranges have been determined to be -278 to -396 degrees Fahrenheit (-172 to -238 degrees Celsius) depending on where it is in orbit; for comparison's sake, absolute zero is -459.67 F (273.15 C), meaning temperatures on Pluto can be ridiculously cold. In addition, it might even snow on Pluto, though it's not like the snow we all know of on Earth; the snow on Pluto might be made of frozen nitrogen.
3. Pluto is active
When scientists began seeing the increasingly more detailed images of Pluto, they noticed that the dwarf planet contained practically no craters, initially bewildering scientists. Most of the solar system's planets and moons are covered in craters, the result from continual bombardment of asteroids and other space debris. Non-cratered planets such as Venus, Earth, and Mars, usually have geological activity that eventually covers up craters with new terrain. This suggests that Pluto's surface cannot be older than 100 million years old (which, in geological terms, is very young) and indicates ongoing geological activity. Pluto also has surprisingly large large ice mountains, eclipsing heights of around 11,000 ft (3350 meters), further signaling geological activity.
4. Pluto's atmosphere is pure nitrogen and it's escaping into space
As the New Horizons spacecraft approached Pluto, its PEPSSI (Pluto Energetic Particle Spectrometer Science Investigation) instrument detected nitrogen atoms from Pluto's atmosphere at a distance seven times Pluto's radius, much further than scientists anticipated. We always knew gases escaped from Pluto's atmosphere through a process called hydrodynamic outflow, but the new data indicates that Pluto is losing its atmosphere even faster than we previously thought. However, that they found nitrogen so far away wasn't the real shocker: New Horizons didn't detect any other sorts of gases, suggesting Pluto probably has one of the purest nitrogen atmospheres in the solar system.
5. Pluto's moon Charon is much more complex than we imagined
For years, scientists assumed Charon was a featureless ball of ice, but new images from the flyby proved their assumptions as incorrect. Charon is littered with troughs, cliffs, and deep canyons (one of which is astronomically deeper than the Grand Canyon). In addition, Charon's lack of craters might indicate it has geological activity like Pluto. Not only that, but Charon has a peculiar dark spot at its top, and two hypothesis exist trying to explain its existence. One suggests that it's simply the result of a massive impact in the past while the other demonstrates the spot could be a result of gases ejected from Pluto over time, eventually collecting on Charon. It is unknown which one is correct, if either at all, though.
Despite these five facts, it will still take New Horizons sixteen months to beam back all the data it's collected during its flyby, meaning there's still much, much more to learn about the dwarf planet. I, for one, am extremely excited to learn all there is to learn about Pluto.
And that wraps up my article. Big thanks to Eddy for helping me a bit with this article. I hope it was an engaging and interesting read for all of you. I'm curious to see your opinions on the Pluto flyby and perhaps your predications about data that will be revealed in the future. We'll see you in the next issue of The Purist!