Nasa’s New Horizon’s mission to Pluto on July 14th has captured our hearts and minds like no previous space mission.

Perhaps because of the emotion widely expressed when Pluto was demoted from the status of planet to that of dwarf-planet in 2006, and surely also because of the extraordinary effort needed to send a space probe on a nine year, 5 billion kilometre journey to such far regions of our Solar System.

The heart-shaped feature spotted on Pluto from New Horizon’s latest image only yesterday also helps – with cartoon editions already online and going viral – including one depicting Pluto the Dog.

With the New Horizons space probe having just “phoned home” shortly after 1am Irish time today to confirm it had survived its closest approach, it is now set on transmitting back the vast number of images captured yesterday – so much data that it will take more than a year to complete. This is the last major moment of discovery of one of the traditionally regarded planets in our Solar System, so it’s a moment to savour.

The number nine seems to currently resonate with Pluto. When discovered it was the ninth planet of the Solar System. We are in the ninth decade since it’s discovery and the New Horizons mission took just over nine years to reach the Pluto. So what better time to look at the nine most intriguing aspect to Pluto and the enigmatic New Horizons mission?

1. A fitting tribute

Pluto was discovered by American astronomer Clyde Tombaugh (1906 – 1997) in February 1930, when he spotted Pluto on photographic plates moving among the stars in the Sky. It is surely a fitting tribute that attached to the New Horizon’s space probe is a container with a small quantity of the ashes of Clyde Tombaugh, and an inscription that reads:

“Interned herein are remains of American Clyde W Tombaugh, discoverer of Pluto and the Solar System’s ‘third zone’ Adelle and Muron’s boy, Patricia’s husband, Annette and Alden’s father, astronomer, teacher, punster, and friend: Clyde W. Tombaugh (1906-1997).”

2. Baby, it's cold outside but...

Pluto is not like any world we have seen before. Even though its surface is at an incredibly cold -229 C, it is more active than any of the other icy worlds in the outer Solar System. It has an atmosphere, weather, and even seasons, and we might even see shifting dunes with sand made of grains of pure solid nitrogen!

3. Not demoted – reclassified!

While Pluto’s demotion from its status of Planet to that of Dwarf-Planet sparked wide and emotive reactions, it is actually better to regard it as a reclassification than a demotion. In recent times we have discovered a region beyond the planet Neptune called The Kuiper Belt containing more than one trillion small icy worlds and 100,000 dwarf-planets with diameters in excess of 100km, of which Pluto is the primary example.

So, Pluto’s reclassification is to a brand new kind of object – dwarf planet – a reclassification which is critical to our understanding of how our Solar System, and indeed Earth itself, formed.

4. Fifth rock from the sun?

One intriguing aspect of dwarf-planets is that they did not originate where we see them now. About half of them – including Pluto – were created far closer to the Sun, about where Jupiter is now, and have been shepherded to the outer region of the Solar System throughout the ages by Jupiter, Saturn, Uranus and Neptune.

5. A double act

Pluto is actually part of a double system. Pluto’s diameter is about 2,400km, while Charon - the largest of its five moons – has a diameter of 1200km. Both orbit a central point every 6.4 Earth days; and just like our Moon only shows one face to Earth though tidal-locking, both Pluto and Charon are similarly locked together so that each has a day lasting 6.4 Earth days, with each only ever showing the same face to the other!

6. The fastest mission in history

Pluto is so far from Earth that to get the New Horizons probe there in under 10 years, it had to be the fasted launch in history – 60,000 kilometres per hour (kph). At the speed, New Horizons could travel from LA to New York in just over 4 minutes. Even still, that wasn’t enough to get it there on time, and so in 2007 Hew Horizons was sent to the planet Jupiter for what is called a gravity-assist, boosting its speed by a further 9000 kph, without which it would only arrive at Pluto in September 2016.

7. Breaking new ground for space exploration

Such is the time delay in communicating with New Horizons at Pluto – nine hours round-trip time for radio communications – that the entire close approach had to be completely automated, with no human interaction. This was rehearsed multiple times on route, and was 100% successful – leading to a new level of automated space missions than will allow us to go even further into the Kuiper Belt.

8. New Horizons phones home

Perhaps the most extraordinary aspect to this mission is that, at precisely four hours and 25 minutes before New Horizons reached its closest point to Pluto yesterday, NASA sent a radio beam from Earth that reached Pluto at precisely the same time as New Horizons, bounced off Pluto’s surface and was picked up by New Horizon’s radio receiver. New Horizon’s used that radio beam echo to measure details about Pluto’s surface and atmosphere.

9. Even more on the horizon

The New Horizons mission is aptly named. For the entire history of space exploration, reaching Pluto has been the ultimate goal of Planetary Exploration. That has now been achieved and future missions will go even further. Indeed, New Horizons itself is set to visit one, and perhaps two small Kuiper Belt worlds in 2018 and 2019. And indeed just around the corner in 2018 is NASA’s new Space Launch System - so powerful that it will be able to tale a probe similar to New Horizons to Pluto in just three years.

Having now explored Pluto, we can say that the first Reconnaissance of the Solar System is now complete. We have visited all of the planets (and most important dwarf planet!) at least once. Such an achievement sets our perspective of our place in the Universe a little more broadly, and set a new benchmark – new horizons - of exploration for the next generation of intrepid space explorers.

As Stephen Hawking stated in his congratulations to the New Horizon’s team yesterday “ We explore because we are Human”, and that is set to continue in the most exciting of ways, thanks to New Horizons and the future missions it will inspire.

Kevin Nolan is Outreach Coordinator to Ireland for The Planetary Society. He blogs at Planetarie or you can follow him on Twitter @kevinolan