Pluto has always been considered the last outpost of the Solar System and now we've finally sent some amazing, nuclear powered technology there to check it out.
Since its discovery, Pluto has always been considered the ninth planet from the Sun. However, after the recent discovery of a another object called Eris which is much, much further away than even Pluto is, the designation of 'dwarf planet' came into being which included both Pluto and Eris, along with other bodies such as Ceres, Haumea and Makemake.
"Officially we now have only eight major planets in the Solar System!"
There is a lot of argument about the size of Eris compared to Pluto so the debate continues, although some of these questions will get answered on 14th July 2015 when the NASA's New Horizons spacecraft makes its closest approach of this mysterious little rock.
New Horizons was launched on 19th January, 2006 from Cape Canaveral. After a swift encounter with an asteroid, the spacecraft flew onto Jupiter getting a massive gravitational assist from the huge gas giant, flinging it into the outer Solar System at 58,536 Kilometres per hour.
Once past Jupiter, New Horizons was put into hibernation mode for the rest of it's 7.5 Billion kilometre journey, finally being woken in December, 2014 for course corrections and to check out it's systems ready for the encounter this coming Tuesday.
Pluto has a really interesting system of moons!"
We've known about its moon Charon for a while now. Both Pluto and Charon are tidally locked together and many scientists consider the system to be a twin dwarf planet because of this.
Charon was only discovered in 1987 (on my birthday! I was 11 at the time), Nix and Hydra were found in 2005, Kerberos in 2011 and Styx in 2012. The Hubble Space telescope made a major contribution to these discoveries.
Some of the moons in the Pluto system seem to have chaotic orbits and it must have been challenging for the team behind New Horizons to plot the right course through the system to maximise their visibility and reduce danger to the probe.
Some theorists say that these minor moons are captured asteroids and other think they were formed in a big strike on an early Pluto, similar to how our own Moon was formed.
Whatever they are, we're getting closer and closer and at the time of writing, New Horizons is on target and preparing for it's rendezvous in Tuesday. I've included a short video below about the mission and there's a long one linked to at the bottom of this blog post.
Facts & Figures about Pluto:
It has mountains of ice as high as the Rockies
It has a diameter of 2,370km (+- 20km)
It has 5 moons: Charon, Hydra, Nix, Kerberos and Styx
It takes 246.04 Earth years to complete a full orbit
it has a surface temperature of -229°C
What a fascinating little world Pluto is!
As New Horizons is so far away now, all of the observations are pre-programmed. We can't slow it down enough to put it in orbit, so it will go whizzing by at a fair old rate of knots. In fact, New Horizons is the fastest man made object ever built and will eventually overtake Voyager when it passes through the Kuiper Belt, the Oort Cloud and finally off into interstellar space.
So what will the spacecraft tell us? Quite a lot actually, as it has many different types of instrument on board all waiting to do science then report back. But it will take time to get all that information back to us. 18 months in fact! That's because of the distance of the spacecraft to us and because of that we only get a data reception rate of around 1Kb per second via NASA's Deep Space Network.
In today's fibre enabled world that seems incredibly slow and we'd almost expect to hear a modem chirping away as we connect to it to send and receive data, but the science will be well worth the wait.