global mosaic of pluto in true color

When New Horizons Came To Pluto

Erin Guinan is studying a Masters Degree in Astronomy & Astrophysics and is on her way to becoming a star.

Sitting and looking to the stars as a youngster, I asked the same questions that the smartest scientists in the world are currently querying. These are questions that will change our understanding of the universe as a whole and life itself once we find the answers. The more you study something you are passionate about, the more questions you have. Human innovations in science and technology have allowed humans to push the boundary into the final frontier of space. Yes, we have only just placed our toes in the shores of the cosmic ocean, but there is something so amazing to hear about us as a species successfully landing rovers on other planets in the Solar System. Many rovers that have been fully functional for years, map out vast detail into the planets with probes being sent to map the distant regions of the Solar System in greater detail. Recent advancements have seen us landing a probe on a comet, as well as sending a probe into orbit to capture dwarf planet Ceres in greater detail. The best part though, is imagining the possibilities of the future space faring generation as technology advances.

On Tuesday July 14, 2015, the human species achieved something rather special when the New Horizons spacecraft flew by dwarf planet Pluto. This mission struck a special place in the hearts of many people all over the world. But why?

Looking at the facts, we will see that Pluto really isn’t much at all. Pluto is small. Pluto is even smaller than Earth’s moon. It has a tiny radius of 1,185 kilometres, and resides at a distance of 7.5 billion kilometres from the Sun. For a sense of scale, that is just 32.6 times further out from the Sun than Earth. From this vast distance, Pluto doesn’t receive much sunlight to warm its small surface, and as a result, the temperature is bitterly cold – with temperatures sitting somewhere around -233 degrees Celsius. Not ideal. Furthermore, Pluto takes 248 Earth years to complete one orbit around the Sun. So what is so special about such a small piece of frozen rock residing within the outer depths of the Solar System?

nh plutosurface

Perhaps it is because Pluto is unlike its companions in the outer Solar System. Up until 2006, all students were taught in schools that Pluto was a planet. There were two types of planets: the rocky terrestrial planets of the inner solar System, and the Jovian gas giant planets in the outer Solar System. And then there was Pluto. So small, so cold and so far away. But then astronomers began discovering more objects similar to Pluto, beyond its distant orbit in the region of the Kuiper Belt. It wasn’t so alone after all. In fact, since then, astronomers have also discovered five moons orbiting Pluto alone. Its demotion in 2006 struck a negative place in the hearts of many people from all walks of life over the world. People became attached to Pluto. After all, it was only tiny and all alone – or so everyone thought. A handful of astronomers sat down together and decided that there should be three factors to determine what makes up a planet.

It must maintain hydrostatic equilibrium – essentially be rounded in shape.

It must orbit the Sun.

A planet must be the dominant object within its orbit.
The downfall of Pluto came from this factor. Pluto, in fact, and its largest Moon Charon orbit each other around a common centre of gravity and therefore, Pluto is not the dominant factor in its orbit.

pluto in colour web

The recent mission to Pluto is the perfect example of just what we are capable as humans. The New Horizons spacecraft represents the fastest spacecraft ever launched, leaving Earth orbit at a velocity of 58,536 kilometres per hour. In perspective, New Horizons is 100 times faster than a commercial airplane, travelling at this speed out of the Solar System to a distance of 7.5 billion kilometres took nine years. And yet, just before 10pm Australian time on Tuesday July 14, the New Horizons spacecraft flew within 12,500 kilometres of Pluto at closest approach – which was spot on target. From this distance, light takes four hours to reach the Earth, and data will continue to be sent back to Earth over the course of the next sixteen months to provide us with an incredibly accurate representation of the dwarf plant, its geology and surface features visible. Some of the first in depth images show a visible love heart shape out of the surface geology. Surely this is a sign that after all this time, and after everything we have done to it, Pluto still loves us after all.

Photographer: New Horizons | NASA

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