Caoimhín's Content

In today’s piece we will be continuing our tour of distant objects by taking a look for Haumea, the most likely dwarf planet after Pluto and Eris. Pluto and Eris of course have their own articles and videos on this site already. Ceres is another dwarf planet, and being in the asteroid belt makes it the closest one to us, but Ceres will get its own video at a future date, potentially when we’re looking at asteroids more generally.

Taking a look at the sky here very quickly, we do still have Venus visible just above the sunset, while Saturn is almost in the middle of the sky by the time it’s dark. The Square of Pegasus is getting nice and high in the sky as well, it is still sharing space with the summer triangle early in the evening. By the time it’s actually dark, as early as 6:30, we can see that the summer triangle is definitely more towards the West and the Square of Pegasus is a lot closer to due South.

Getting back on track, we are going to be looking for Haumea which is invisible to the naked eye. It doesn’t matter if we go out to the countryside even without light pollution Haumea is an incredibly distant object only visible through larger telescopes. I don’t know exactly where it is , so I can’t guarantee that it will be above the horizon during the day for Ireland, or indeed anywhere on Earth. Stellarium is thankfully there to help, indicating that Haumea is over in the West, just above the Sun as it sets. This puts in an almost circumpolar position, so it will rise above the horizon again in the morning just before the sunrise, at about 5:30 in the morning. Haumea is just under Arcturus at the moment, which that means that Haumea won’t be too hard to find. We’ve got the Plough nice and high above the East just before the sunrise as well, we can follow the arc of the handle of the Plough to Arcturus and just underneath it there will be Haumea.

Haumea, like how-may-a or /haʊˈmeɪ.ə/ is how I am pronouncing Haumea in English, huh-oo-meh-yuh or /hə.uˈmɛ.jə/ may be closer to the original Hawaiian because it is a Hawaiian name. As we move further out we’re looking at things that we’ve discovered more recently. Even though the tradition of naming planets after Greek and Roman mythology was the tradition all through the 1700’s and 1800’s, from the classical times right through to the modern day, as we started to discover more and more and as astronomy became more international, objects started to get names in other languages. This is something I’ve mentioned before and it will be a prominent theme in some upcoming videos as well.

Haumea is one of the candidate dwarf planets, listed in Stellarium as a dwarf planet. As a trans-Neptunian object of course its year is incredibly long, almost 300 Earth years, but I don’t see a day length in Stellarium. However, I do know that Haumea spins very quickly, enough to effect its shape. There are 2 moons, around Haumea, Hi’iaka and Namaka and these are also Hawaiian names, I will continue using an apostrophe to represent the Hawaiian ‘okina. Moons like these are very useful when it comes to figuring out more about distant objects in space. Stellarium lists a diameter of 6000 kilometers which is certainly incorrect, Haumea’s longest axis is only about 2000 kilometers, which is still pretty big, definitely similar to the size of some of the other dwarf planets. As I’ve mentioned before, size isn’t really what matters, what matters, well as well as size, is hydrostatic equilibrium. Dwarf planets need to be solid balls of rock, objects that have fully coalesced, not just loose groups of material kind of floating around together, which some of these distant objects seem to be. We’ve never visited Haumea, but because of the moons that are orbiting it, we’ve got a fairly good idea of its density and its mass, and density and mass are some of the more important things when it comes to determining if something is a dwarf planet or not.

Speaking of Pluto and Eris, let’s just take another quick look, just to see the size of them. Pluto’s diameter is just under 2400 kilometers, and it has a day period there of hundreds of hours, which indicates that Pluto is rotating pretty slowly. If we look at Eris we should get another similar value for its diameter, just over 2300 kilometers with no day length listed. It also has a very, very long year. We know that Haumea is rotating quite quickly partly because of its slightly strange shape, which it seems to have acquired thanks to the speed of its rotation. Earth is a slightly oblate spheroid thanks to our spin, but Haumea seems to be a Jacobi ellipsoid, almost twice as long on one axis than on the other two. this makes Haumea almost bullet-shaped. With a diameter of a couple of thousand kilometers across, this would bring it to be the right size to be a dwarf planet. However, if it is a loose collection of rock the right size to be a dwarf planet, then it’s still not a dwarf planet because it’s a loose collection of rock. These things need to be solidified together, a hydrostatic equilibrium needs to be reached so there needs to be enough pressure on stuff on the inside to kind of smoosh it all together.

There is some controversy around the discovery of Haumea. As well as being an object that may be a dwarf planet and all the controversy about dwarf planets, Haumea was or seems to have been discovered by one group of researchers and then also discovered by another group of researchers. The second group of researchers, or so it seems, announced it first, even though, apparently, the first group of researchers discovered it first. As such, Haumea, this Hawaiian name, is the name that has currently been accepted and that was proposed by the Americans astronomy team. This team were working as part of Caltech, out of Palomar Observatory in the USA. They found Haumea apparently around 2004 but they didn’t announce it. There was a Spanish team of astronomers, working out of Sierra Nevada observatory in Spain, who also discovered Haumea. They announced it first and apparently the Spanish team was working with images they had taken first, images taken in 2003 with the discovery announced in 2005. Even though the American group had apparently discovered it in 2004, they hadn’t announced it. People don’t always rush to announce these things, if you make a mistake it can be quite embarrassing, so double-checking your results and making sure that you’ve discovered what you think you have is very important in astronomy.

In Stellarium no discoverer is listed and as far as I can tell there’s no discoverer officially listed by the International Astronomical Union either, so they’re not saying who discovered it officially. However, the name Haumea was proposed by the American group, the Spanish group had proposed Ataecina, the name of an Iberian Goddess rather than a Hawaiian Goddess. Still getting named after a goddess so that’s something at least. The name of the Iberian goddess comes from some extinct language, an extinct indigenous Iberian language or an extinct Celtic language from Iberia. Ataecina seems to have been worshipped by Celt-Iberians and native Iberians and Lusitanians, and so the name may come from Celtic, another Indo-European language, or a completely separate language possibly related to Basque. It is believed that she was a goddess of the underworld, a chthonic deity, just like Pluto. As a non-plutino, this name wasn’t considered appropriate for that reason as well. Either way, even though the official discover of this is considered controversial the name that’s been given is the name from the American group, so it seems like they have been accepted as the discover regardless of any controversy. However, the Spanish team who also found Haumea, whether they found it afterward, before, or even if they found it afterward from pictures taken before and were just the first people to say it, they also found it. I don’t know the truth behind the controversy or all of the details, but I will mention both groups that were involved in the discovery because there was controversy about it. I may not know the truth but I will at least acknowledge the fact that there was some controversy involved,

That is Haumea, we will continue looking at these distant objects but as we move forward we’re going to be looking at objects where their status as dwarf planet is less certain. Other than Ceres of course, the status of Ceres as a dwarf planet is pretty well accepted, but for a lot of the other objects their status as a dwarf planet is less clear. There are a lot of objects that are considered candidate dwarf planets even though they’re not actually considered full dwarf planets yet, we just don’t know enough about them to say for sure.

Briefly coming back to things we can see while here we are here nice and early in the morning. I say nice and early in the morning, but 7:15 is almost late in the morning. Certainly in the countryside both Mars and Jupiter are very clearly visible. Jupiter will definitely be behind tall trees by the time the Sun rises, but it may not be completely under the horizon so if you do have a clear view, even at 8 o’clock you may still be able to see Jupiter. Mars is definitely still there if you’re in the countryside, far clear of either horizon at sunrise. No Mercury yet, we will be waiting until December before Mercury comes back in the morning. If you’re close to the equator, if you’re in the right location you may still be able to see Mercury in the evening at the moment, though not for long. Mercury will be disappearing, getting too close the Sun in the evening sky very soon.

I hope you enjoyed this quick piece talking about Haumea, a little bit about the controversy behind its name and a little bit more on dwarf planets and how some objects can be kind of on the edge of the definition. If you did enjoy this article then please do you like it. You can also support my content by subscribing to this website and my YouTube channel. Hopefully, I’ll see you back here next time.