By Yong Jian-Yi, a Master Science Educator at Science Centre Singapore who also hosts Live Planetarium Shows at the Omni-Theatre.
On the 14th July 2015, the Space probe New Horizons travelled to 12,500km away from Pluto. This marks humanity closest encounter with the once planet. The mission was initiated in 2007 and it took almost 9 years for New Horizons travelling at about 49,000km/hr to reach Pluto, but what is Pluto and what made us spend almost 700 million USD on this mission?
Pluto as a planet was discovered in 1930 by Astronomer Clyde Tombaugh; however gravitational perturbation caused by its orbit around the sun was observed and Pluto had been predicted to exist since 1904 by Astronomer Percival Lowell. He called it “planet X”. Originally conceived as the 9th planet within our solar system, its status became controversial in 1992 with the discovery of other planetoid which also orbits the sun in its general vicinity. Pluto was officially downgraded in 2005 to the status of a “Dwarf planet”. Several of the other planetoid followed suit and also became classified as dwarf planet. Besides Pluto, New Horizons also imaged several other astronomical objects. Significantly Asteroid 132524 APL, the eruptions of IO a volcanic Moon orbiting around Jupiter and also the many moons of Pluto. The discoveries that New Horizons made may cause us to revise how the Solar system is formed and keep many Scientist occupied for years to come.
Pluto appears to be largely an Ice planet, perhaps even more ice than rocks. Ice on Pluto serves the same function that rocks do on earth. Mountains, cliffs and even canyons, formed from ice. A thin layer of nitrogen gas makes up the Plutonian atmosphere. There are some observations that may indicate some form of gaseous exchange taking place between Pluto and its largest moon Charon, this can only possible because of the relative size of both Pluto and Charon which are not too dissimilar. In fact both orbit around a common point outside the body of Pluto. New Horizon has also confirmed that Pluto is the largest dwarf planet within the solar system, outsizing Eris, the past contender.
We can hardly talk about Pluto without bringing out its Moons. Pluto has 5 other moons that orbit the dwarf planet. Charon, Styx, Kerberos, Nix and Hydra, most of them are tiny in size except for Charon. There seems to be indication that Pluto was formed differently from Charon, and that Charon was “captured” by Pluto rather than both being formed from the same event. Pluto is also a comparatively “young planetoid”, as there doesn’t appear to be much cratering on its surface.
Although much still remains shrouded in mystery, the trip of New Horizons have ignited much curiosity and wonder among earthlings. How is it able to maintain an active geological activity? Whys doe it looks so reddish compared with Charon? We may not be able to answer them anytime soon, but may we always look to the sky, and wonder.