By Duncan Steel 04/09/2019 4


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The International Astronomical Union (IAU) — the global organisation of professional astronomers — is marking its centenary this year by inviting different nations to propose names for both a distant star, and a planet found to orbit it (a so-called exoplanet). Anyone can suggested a moniker, for the star, for the planet, or both. So: calling all New Zealanders to suggest names suitable for ‘our’ celestial pair!

Let me begin by saying that I will not be proposing names myself, as I’ve had the privilege already of labelling many minor planets (usually called asteroids, but the IAU prefers the ‘minor planet’ terminology). My sons (5263 Arrius and 6828 Elbsteel) are spoilt, as are my parents, siblings, and the little town where I was born, amongst others. It is not the done thing to suggest one of your minor planet discoveries be named for yourself, and so for my own asteroid (4713 Steel) I am indebted to Rob McNaught, who worked with me on the Anglo-Australian Near-Earth Asteroid Survey (AANEAS).

So, it’s time for others to have a turn; including you, dear reader, should you so choose.

Generally-speaking, the only objects for which individual astronomers and space scientists can suggest names are minor planet discoveries, and features on planetary surfaces (as we map them in ever-better detail). Comets automatically get the name of the discoverer(s); for asteroids/minor planets the person designated as the discoverer (a complicated matter) has the privilege of suggesting a name once the orbit is well-determined, subject to various rules on suitability. The acceptance of proposed names (or otherwise) is the job of the IAU’s Committee on Small Body Nomenclature, which for many years was chaired by Pam Kilmartin of Mt John Observatory near Lake Tekapo. If you want to learn more about how these and other celestial objects are named, see here.

The opportunity now is for New Zealanders to propose names for a star and an exoplanet (or exoworld) which have been selected by the IAU for our antipodal appreciation (with Australia getting its own twins to title). Here is the core NameExoWorlds webpage from which you can learn much more, the original press release being available here.

This move to enable the public to name exoplanets has created considerable media interest elsewhere, but not much as of yet in NZ (apart from this), so it is perhaps time to get a debate going… we’ve only got until the end of the month to decide on appropriate appellations. There’s already a Wikipedia page about this project. The Royal Astronomical Society of New Zealand has gazetted the opportunity to its members, which is great, but having wider public input would be wonderful. Let’s get it right.

Artist’s impression of an exoplanet seen from one of its moons. Graphic: IAU/L.Calçada

In NZ there are 38 members of the IAU (Australia has ten times more), representing the professional side of astronomical research and teaching. Obviously there is a far larger number of amateur astronomers, many of them doing important work for the science, a good fraction of them being members of thriving local astronomical societies, which is to be applauded. On top of that, astronomy and space represent topics that are of close interest to the broader public. I imagine that amongst all such people there must be some excellent ideas for names for this star and exoplanet, of which I will write more below.

Before getting to that, let me give some information about how this naming opportunity is being run in NZ; obviously you could have learned much from clicking the various links I offered above, but there are also various NZ-specific things to note.

New Zealand has an IAU National Outreach Coordinator, Dr Nicholas Rattenbury of the University of Auckland; he is an expert on the search for exoworlds (planets orbiting stars other than the Sun), and you can read more from him here.

Rattenbury and colleagues at the Auckland Space Institute have set up a wonderful website giving more information, and enabling anyone to enter a suggestion for the star and exoplanet names. There is also a splendid webpage linked there wherein most of your questions will likely be answered. The specific IAU naming rules for the NameExoWorlds project are available here.


At this stage many readers will be thinking that they have heard of people buying names for stars or other celestial objects, so what is new here? Whilst there are many companies around the globe offering smart certificates stating that a star has been named for you (all in return for a few dollars, euros, roubles or shekels, of course), in fact there is no real basis for such tags. That star you think you have bought may well ‘belong’ to a dozen other mugs.

This is what the International Astronomical Union states in this regard:

As an international scientific organisation, it dissociates itself entirely from the commercial practice of selling names of planets, stars or or even “real estate” on other planets or moons. These practices will not be recognised by the IAU and their alternative naming schemes cannot be adopted. 

Sorry! Further information can be found here, and here, and here, and here, among many other webpages. Alternatively, you might want to take a look at this piece and similar commentaries; for the record, I am one of the members of the IAU who disapproves of the 2006 re-classification of Pluto from ‘planet‘ to ‘dwarf planet‘.


The NameExoWorlds project, though, is the real deal. The IAU would like its member nations to put forward suitable names for allocated stars that have been found to have planets orbiting them, plus those planets themselves. A few years ago a similar competition was run, with interested parties invited to submit names. The results are shown in the graphic below.

The winning titles and brief descriptions of the chosen names from the IAU NameExoWorlds competition held in 2015. The names for 31 exoplanets and 14 host stars, voted for by the public, were accepted and have been officially sanctioned by the IAU. The winning names are to be used freely in parallel with the existing scientific nomenclature. Graphic: IAU.

Now let us turn to the specific star and exoplanet that NZ has been allocated. Summary information is given by the IAU here, with a link to this NASA exoplanets webpage. I am a bit bemused by the following, which I grabbed from the latter webpage:

Well, of course it’s visible from Earth, else we would not know it’s there! I think they meant it’s not visible to the naked eye. It is visible by eye using a relatively small telescope, and that was one of the reasons it was selected. It’s also deep in the southern sky, in the constellation Apus, so that (clouds allowing) it should be visible year-round from New Zealand; again, a reason for its allocation to NZ.

The above is an artist’s impression of this star (not an actual photograph!), but it’s fairly easy to imagine what this star looks like as it’s a G-type, the same as our own star, the Sun. That means it’s a yellow dwarf star.

Why HD? Well, that stands for Henry Draper. You might now jump to the conclusion that Draper, a 19th century medical doctor and amateur astronomer who had the good sense to marry a rich wife, enabling him to dedicate himself to scouring the skies, must be the person who first catalogued this star… but you would be wrong. It happens that many talented and dedicated women astronomers can be linked to how the labelling of HD 137388 came about.

Draper and his wife Mary Anna were pioneers of the use of photography in astronomy, work that came to an unfortunate end when he died of pleurisy at only 45 in 1882. Mary Anna then established the Henry Draper Medal, to be awarded by the US National Academy of Sciences for “investigations in astronomical physics”. Subsequently she donated their equipment plus a large sum of money to the Harvard College Observatory, that funding being used by the observatory director (Edward Charles Pickering) to hire numerous women to work as ‘Computers‘ there. Some of these women have names that are still well-remembered in astronomical circles; names such as Anna Winlock, Williamina Fleming, Annie Jump Cannon (see here also), Henrietta Swan Leavitt, Florence Cushman, and Antonia Maury.

Those women astronomers just listed, plus many others (apparently 80 in all, over the decades), worked on several research projects but in particular the classification of stars in accord with characteristics of their spectra recorded photographically – a topic that Henry and Mary Anna Draper had pioneered – resulting in the Henry Draper Catalogue of stellar spectroscopy. When that catalogue first appeared in 1918-24 it contained about 225,000 stars, since when around another 135,000 have been added.

And that’s how HD 137388 got its capital letters, and its number.


The exoplanet that is in orbit around that star currently has a designation (i.e. HD 137388 b) that follows rules set by the IAU: the addition of that lower-case letter b to its stellar master’s designation. The two single-spaces in the sequence “HD 137388 b” are also de rigueur.

What if a whole batch of exoplanets are discovered circuiting some star? The answer is that the alphabetical sequence continues: b, c, d, … As I write the Exoplanet Catalog(ue) maintained by NASA personnel contains about 4,000 exoplanets distributed across around 3,000 systems; that is, whilst most stars so far discovered to be accompanied by orbiting planets have only one such planet yet identified, there are several hundred that have two, three or more exoplanets found to be looping around the stars in question. Study of these has let to a whole new branch of astronomy being introduced: exoplanetology.

So, what is this HD 137388 b like? Apparently (see here) it is a gas giant planet (Jupiter, Saturn, Uranus and Neptune are gas giants in the solar system) with a mass estimated to be about one-fifth that of Jupiter, making it similar in size to Uranus or Neptune. It is far closer to its parent star than our gas giants, however, a bit nearer than Earth’s orbit around the Sun; and it also had an orbit than is far from being circular. Not the sort of location we might anticipate finding life-as-we-know-it… but who knows?

Getting back to the chase, HD 137388 b is the planet for which New Zealanders have been invited to propose a name, plus a suitable title for its parent star HD 137388. Those formal labels will remain in various astronomical catalogues, but an additional layer of naming – more user-friendly, if you like – will be adopted by the IAU. I mean, Henry Charles Albert David of the House of Windsor remains the formal name of the Duke of Sussex, whom we usually reference as Prince Harry, and his mother was never properly Princess Diana, despite it being the way in which people frequently mention her.

Let us leave this all aside. What might we call this star and its planet, in order to reflect New Zealand in some suitable way?


An obvious suggestion is Aotearoa and New Zealand. Ah, well there are already minor planets named both Aotearoa and New Zealand. The former was named by the previously-mentioned Alan Gilmore and Pam Kilmartin, their Wikipedia entries containing a list of their discoveries and the names they have so far suggested for them, including 3563 Canterbury. The latter (386622 New Zealand) was discovered in 2009 by Jennie McCormick at Farm Cove Observatory (it’s near Half Moon Bay, of course) in Auckland; nice one Jennie!

If you would like to see the full list of minor planet names, just click here. That list will give you some ideas of what names have been used for solar system objects, although it does not follow that names already given to such minor planets cannot also be used for celestial objects elsewhere. (There are, by the way, some doozies in that long list, and I plan to write a post one day about a few of them.) A note in passing: according to the formal IAU rules, the number (a sequence that begins with 1/one for 1 Ceres which was discovered on the first day of the nineteenth century, it happens) before the name should be contained in parentheses; thus (1566) Icarus, (1862) Apollo and so on. Seems a nuisance to me.

I started this post by saying that I would not be proposing names myself for the star and exoplanet allocated by the IAU to New Zealand. However, I might make a suggestion for readers to ponder. There is no minor planet (yet) named Matariki, but in any case why would we double-up on a te reo term that already has a celestial association? Alternatively, I think of my own current work, making use of satellites in Earth observation research, through which I have become aware of the terms āmiorangi and waka tawhio being used to describe artificial satellites. What, then, might you come up with in te reo to describe a distant star somewhat similar to our Sun, and also its accompanying planet? Have your say via the website linked here.


The author arrives at asteroid 1 Ceres. OK, it’s just a road sign (in Fife, Scotland), but I drove around for what seemed like hours until I found a sign just the right distance (one mile) away from that little town.

4 Responses to “An invitation to name a star and a planet”

    • Hi Jack: Thanks for the input, but it is not me to whom you need to suggest names. The webpage where you can enter your ideas for names is given as a link accessible by clicking on the very last word (“here”) in the main text above.

  • Star – ‘Hinepiata’ . This name is Maori for ‘Maiden of Light’.
    Planet – ‘Te-aka-puaho’ The farthest aand most strategic point of the sacred mountain of the Tuhoe people, Maungapohatu.
    Hinepiata is also the name given to our new born grand-daughter. We belong to the family of light and connect with the environment/universe just as other indigenous cultures do, a significant and traditional practice of our cultural heritage.