New Horizons

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New Horizons will launch in the next day or two..

Its the first probe to explore the exotic and far away place known as Pluto. Its a long way from Earth – 38 Astronomical Units (AU), give or take, depending on its orbit. To put it another way, one AUis 149 million kilometres, eight light minutes or the distance between the Earth and the Sun, depending on how you want to look at it. Now do the multiplication of 1 AU and you come to a total of 312 light minutes from the Sun, or 5.2 hours. To give you an idea of the scale, Mars is 1.4 AU and Jupter is 5.2 AU from the Sun respectively and it still takes space probes months and years to travel to them.

In short, space is Big. Really Big. In fact, its so Big that if you were ever walking down the path and ran into it, you would say to yourself, “Wow, that’s big!

Cheesy line, but I’ve wanted to say it for months and now is as good as time as any!

Why is Pluto so interesting?

First off, there’s debate still as to whether its a true planet. There are those in astronomical circles who mark Neptune as the last true planet and anything thereafter as part of the Kuiper Belt. The best way to describe the belt is as an outer asteroid belt, which in turn is surrounded by the even more distant shell of the Oort Cloud. Lets assume for now that Pluto is a Kuiper object. It isn’t even the largest one. Kuiper object 2003 UB313 currently holds that honour. Nor is it the furthest out. Sedna holds that paticular honour, detected at a massive 97 AU from the sun, with an estimated aphelion of 975 AU.

What we know about Pluto would fill the first page of the comparitive encyclopedias of information we have about Mars or Jupiter. We know Pluto is brown, that it has three moons – Charon, and the poetic S/2005 P 1 and S/2005 P 2 respectively. We know that it has a tenuous atmosphere that cools the planet, as opposed to insulating it.

Pluto’s atmosphere acts in this manner as while its end of the solar system is cold, its still mostly vacuum. There’s nothing to conduct heat or cold anywhere, so it mostly stays the same. When Pluto travels closer to the sun in its eccentric orbit, its surface ice melts and a thin atmosphere forms. This atmosphere acts as a conductor, drawing head away from the surface and radiating it into space, cooling the planet.

And other than the bare facts of its orbit, size, shape and reflectivity, that’s about all we know at this point in time.

So why do we go there? Because its there!

That’s enough Wikipedia links for me, for now. Still, I find it somewhat hypocritical when a person makes a big post on a subject without knowing the first thing about it themselves, so I spent a good three hours last night following all the links and learning all I could about space probes and orbits and moons, until I finally fell asleep. And then I had a weird dream.

I was on Pluto, as it was doing a gravity-assist flyby of Earth (don’t ask me how I knew this…) and I was standing on the leading face. I could see the Earth. The planet was outgassing, from its surface heating up, so it had a comet-like tail, but because of the atmosphere conducting heat away from the surface, the tail came and went, it was like a giant morse code, dot, dash, dot, dash. Weirdness all round.


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