Now we’re beyond the planetary solar system and into something else entirely, what is known as trans-Neptunian space, that is anything that is further away than Neptune on average. The main thing of this part of the solar system is the Kuiper Belt, which is a bunch of junk created during the formation of the solar system that Neptune has apparently swept into a neat big doughnut. Some of the objects from the Kuiper Belt and beyond have crazy orbits so listing the miles things are after another thing is even stupider than it was for the planets.
843 million miles after Triton is:
Orcus can be called the anti-Pluto. This is because its orbit is like Pluto’s in a mirror and it also has a cosy moon like Pluto does. Orcus is icy and the ice is in crystals which are probably from past ice volcanoes. Currently it is hard to know very much about the objects in this part of the solar system because they are so far away and no vehicle has yet had a look at them up close (the hubble pictures of these things are just bunches of pixels) and so it is also hard to know whether these things are round enough to even be looking at at all. Orcus probably is though, it’s nice.
8 million miles after Orcus is:
The harbour at the edge of the world. The friendly face in the darkness. Everyone likes Pluto because they think it’s sitting out there all little and by itself but it actually has five moons and New Horizons will get there next year and start criticising it. Pluto dances with Charon like they are Rose and Jack on the Titanic, which makes them a binary system, their gravitational balance point falls in the space between the two. Its surface is super varied so should be good to look at properly. It is holding organic molecules and water, which is life stuff. Life stuff is found all over Kuiper Belt objects which is why some people think life stuff came to Earth on a meteor from here.
12 thousand miles after Pluto is:
This is Pluto’s little moon (or big moon if talking relative sizes) and phony Irish dancing partner. Nobody knows if it is its own thing that Pluto has latched onto or if it was smashed off of Pluto at some point, they are different colours which shows that they have different compositions. They could be seen as two individual little planets just having a nice time. It probably has ice volcanoes going off on it. Charon was discovered in the 70s by looking at cruddy pictures of Pluto that sometimes had extra blobs on the edge.
As we’ve now reached the outer limits of our classical solar system this would be a good time to try to get some perspective. These distances are unreasonable. I found two things that sort of help in getting your head around it. Here is a scale model of the solar system if every pixel were the size of the moon:
and here’s a spunky man on a bike:
607 million miles after Charon is:
Unlike Pluto, Makemake is definitely a lonely thing. It has no moons and no atmosphere and it does its own orbit, whereas the objects mentioned above have a resonance with Neptune and for every two orbits Neptune does they do three. They also cross paths with Neptune, coming closer to the sun that it does, though because they have resonance they do not crash into each other. Makemake has no interest in that sort of behaviour. It also has a very uppy downy orbit to reinforce the no interest that it has. Its surface is ices.
2 billion miles after Makemake is:
If there ever were things that didn’t care about anything it is this thing and the next thing. They still go around the sun though eventually. Eris takes 557 years to go around the sun but considering how far it is away from the sun (pointlessly far away) that actually seems pretty swift. It is the biggest known dwarf planet and it exists outside of the Kuiper Belt as part of a gang known as the scattered disc, which are things that have been hossed beyond the Kuiper Belt by the giant planets. These things go like boomerangs and comets are these things, going far far away and then coming back again.
That’s about it. One more round thing to go. It’ll take a while to get there, you probably have time to watch Titanic a couple of times if you want to…
43 billion miles after Eris is:
Sedna is currently 8 billion miles from Earth but its orbit is so crazy that 49 billion miles is the average. It takes 11 thousand years to go around the sun. The silly orbit was probably caused by something massive giving it a shove in the distant past. Something that either isn’t around anymore or hasn’t made an appearance yet. Its surface is red and sedate and ancient, the space it travels through is too cold and empty for any impacts or deposits to replace the coating. It is by a long way the most far away round thing but it is very unlikely to be the only round thing that far away, there will be tons more round things flying around beyond Neptune and there should be another 40 – 120 round things doing what Sedna is doing. They even found another one just now but it doesn’t have a proper name so I’m not painting it. I’m fed up with this.
So that’s the end of round things for me. But the solar system goes on for ages and ages after this. Voyager 1 has just toddled through the heliopause where the solar winds lose the energy to fight against the rest of space and in a little while it will spend 20 thousand years toddling through the ice-nugget Oort cloud which stretches half way to the rest of the stars.
If you’d like to buy one of my round things paintings you can do so here.