From Titan's Doom Mons to Mercury's Pourquoi-Pas: how did the landscape of space get its names?

A detail from Ordnance Survey's new map of Mars. Image: OS.

The Ordnance Survey recently made a very nice map of Mars’ Arabia Terra region. This map shows an alien crater-pocketed landscape, peppered with mysterious names like “Aram Chaos”, “Meridiani Planum” and “Marth”.

When the OS makes a map of Britain, it is making a map of a place with history – reflected in place names that come from the many different languages that people have spoken here. But where are the names on the Mars map coming from?

The romance of naming

Space used to be like the Wild West, with different names used by different people. So, in 1911, the International Astronomical Union started to become the official clearing house for space names.

It legitimised features from previous maps (like Schiaparelli’s map of Mars) and made rules for how new names would be picked. It now publishes its database online, and I used this and various NASA maps of other planets to build We Name The Stars – a way of exploring these rules and places.

The IAU conventions seem to understand that there is something magical and important about naming things. We don’t end up with Crater 62 on asteroid BXM-2: each kind of feature (mountains, ridges, craters, lakes) on each different world has a different naming convention, so that similar places are thematically linked. Often revolving around a particular ancient myth, this lends a sense of grandness and history to what is otherwise just some slightly different coloured pixels.

A screenshot from the "We Name the Stars" page on Mars. Click to expand.

Not all names are mythical. Craters on Mercury are named after historically significant artists, while escarpments are named after ships of discovery. This is how you end up with a slope on Mercury named “Pourquoi-Pas”.

Craters on the asteroid Eros are named after “mythological and legendary names of an erotic nature” (which gives us Casanova and Abelard), while Saturn’s moon Titan has places named after mountains in Middle Earth. The largest mountain on Titan is called Doom Mons.

Places We’ll Never Go

Part of the appeal of the OS map is that it reinforces the idea of Mars as a place. It’s a technical challenge, but ultimately we understand how we’d get there, walk around, and get back.

Similarly you can vaguely imagine the 22nd century equivalent of the Arctic Explorer taking the journey my virtual rover is making across the Moon, visiting every crater. But there are plenty of other places to which we’ve given names that will probably never be walked on by people.

Take Mercury – it’s right next to the sun and spins very slowly. Every place on the planet spends every other month staring into the furnace. In several of his books Kim Stanley Robinson solves this problem with Terminator – a city that travels on rails around the planet. The sun heats the rails, which expand and push the city onward – permanently keeping it just beyond dawn.

But this is a fragile solution. Valleys on Mercury are named after ancient abandoned cities – a poor omen for the success of future settlement. Maybe maps of Mercury are for visitors, driving slowly to stay ahead of the sun.


A screenshot from the "We Name the Stars" page on the Moon. Click to expand.

Venus we can’t even visit. In the day the surface can get hot enough to melt lead, and the atmospheric pressure is the equivalent of being a kilometre under the ocean on Earth. On the other hand, it turns out that, if you build floating cities 50km up, the pressure and temperature are pretty much the same as on Earth. To our cloud-dwelling descendants it’ll probably seem odd that we put so many of our goddesses on features as unimportant to them as the floor of the ocean is to us.

There is something strange and wonderful about a system that produces such evocative names for places that in all likelihood no one will ever visit. These names don’t have to be pretty or coherent – but the effort is made anyway.

The European Sky

The IAU was founded at a time when “international cooperation” mostly meant “European cooperation”. The conventions emerging on using old myths and Latinised names were good, because that seemed like common ground.  Astronomers looked into space and then looked back on their shared classical heritage, pillaging the myths of the Romans and Greeks for important sounding but politically neutral names.

Except, of course, it’s not really neutral because not everyone comes from that heritage. Some 60 per cent of feature names are European in origin, and so European myth and history punches a little above its weight in the space naming race.

As the composition of the IAU has changed over time, this shift has been reflected in patterns for future names. Many conventions are now ecumenical: Io is littered with thunder and sun gods from different cultures, and Ceres has features named after the “agricultural festivals of the world”. Rhea uses names from “people and places from creation myths (with Asian emphasis)”; names on Triton are explicitly “aquatic names, excluding Roman and Greek”.

Fragile Monuments

But these are all faraway places, what about European domination of the places we’re actually likely to go – like the Moon and Mars? If the future of space turns out to be non-western, this issue ends up solving itself.

After the Chinese Yutu rover landed on the moon, the landing site was named Guang Han Gong (Moon Palace) and three local craters were given names from Chinese astrology by the IAU. When the asteroid 1998 SF 36 was selected as the target for the Japanese Hayabusa spacecraft, it was designated Itokawa after a Japanese rocket scientist. Where robotic feet go, naming rights follow.

On the Moon there are areas where naming is reserved to honour dead astronauts and cosmonauts, with the ominous note that “this convention may be extended if other space-faring countries suffer fatalities in spaceflight”. And why not? There’s plenty of Moon left, thousands of craters have been identified that have yet to receive an official name.

And even if a feature has a name with a history, will people honour it? Will a Martian Chinese colony in the Rutherford Crater still call it Rutherford? Will Indian settlers in Inuvik keep the name of a small town in Canada – or rename it something closer to home?

There’s a long history of name changes in space. British astronomers carried on with George’s Star (chosen by the discoverer of the planet to honour George III) for many years after everyone else switched to “Uranus”. The Galilean moons were once the ‘Medician stars’ – after the family whose patronage Galileo sought. When Cassini discovered the moons of Saturn he called them ‘the stars of Louis’ after King Louis XIV, hoping to create “a Monument much more lasting than those of Brass and Marble”. That we don’t use any of these names reflects the fragility of monuments that only exist on paper.

European myths may end up the Lingua Franca of empty places – only kept for areas to which no one has any interest in going. If in the future there are settlers in Arabia Terra, that OS map might be an interesting historical artefact for them – a perfectly correct map with all the wrong names. 

You can learn more about space names over at We Name The Stars


Cycling on London’s Euston Road is still a terrifying experience

Cyclists on the Euston Road. Image: Jonn Elledge.

The New Road, which skirted the northern boundaries of London’s built up area, first opened in the 1750s. Originally, it was intended to link up outlying villages and provide a route to drive sheep and cows to the meat market at Smithfield without having to pass through the congested city centre. 

As with bypasses and ring roads the world over, however, it increasingly became congested in its own right. Today, you won’t often find livestock on the route, which is now Marylebone, Euston and City roads. But you will find up to six lanes of often stationary buses, cabs, and private vehicles. In a city whose centre is largely free of multi-lane highways, London’s northern ring road has long been the sort of abomination that you avoid at all costs.

But now, somewhat surprisingly, the road is seeing yet another new use. Earlier this week, the first phase of a temporary cycle lane opened on the Euston Road, the middle section of the route which runs for roughly a mile. As London rethinks roads throughout the city, this addition to the cycling map falls solidly into the category of streets that didn't seem like candidates for cycling before the pandemic.

It is, to be clear, temporary. That’s true of many of the Covid-led interventions that Transport for London is currently making, though those in the know will often quietly admit to hoping they end up being permanent. In this case, however, the agency genuinely seems to mean it: TfL emphasized in its press release that the road space is already being allocated for construction starting late next year and that "TfL will work with local boroughs to develop alternate routes along side streets" when the cycle lane is removed.

At lunchtime on Friday, I decided to try the lane for myself to understand what an unlikely, temporary cycle lane can accomplish. In this case it's clear that the presence of a lane only accomplishes so much. A few key things will still leave riders wanting:

It’s one way only. To be specific, eastbound. I found this out the hard way, after attempting to cycle the Euston Road westbound, under the naive impression that there was now a lane for me in which to do this. Neither I nor the traffic I unexpectedly found myself sharing space with enjoyed the experience. To be fair, London’s cycling commissioner Will Norman had shared this information on Twitter, but cyclists might find themselves inadvertently mixing with multiple lanes of much, much bigger vehicles.

It radically changes in width. At times the westbound route, which is separated from the motor traffic by upright posts, is perhaps a metre and a half wide. At others, such as immediately outside Euston station, it’s shared with buses and is suddenly four or five times that. This is slightly vexing.

It’s extremely short. The publicity for the new lane said it would connect up with other cycle routes on Hampstead Road and Judd Street (where Cycleway 6, the main north-south crosstown route, meets Euston Road). That’s a distance of roughly 925m. It actually runs from Gower Street to Ossulton Street, a distance of barely 670m. Not only does the reduced length mean it doesn’t quite connect to the rest of the network, it also means that the segregated space suddenly stops:

The junction between Euston Road and Ousslston Street, where the segregated lane suddenly, unexpectedly stops. Image: Jonn Elledge.


It’s for these reasons, perhaps, that the new lane is not yet seeing many users. Each time I cycled the length of it I saw only a handful of other cyclists (although that did include a man cycling with a child on a seat behind him – not something one would have expected on the Euston Road of the past).

Though I hesitate to mention this because it feeds into the car lobby’s agenda, it was also striking that the westbound traffic – the side of the road which had lost a lane to bikes – was significantly more congested than the eastbound. If the lane is extended, it could, counterintuitively, help, by removing the unexpected pinch points at which three lanes of cars suddenly have to squeeze into two.

There’s a distinctly unfinished air to the project – though, to be fair, it’s early days. The eastbound lane needs to be created from scratch; the westbound extended. At that point, it would hopefully be something TfL would be keen enough to talk about that cyclists start using it in greater numbers – and drivers get the message they should avoid the Euston Road.

The obvious explanation for why TfL is going to all this trouble is that TfL is in charge of the Euston Road, and so can do what it likes there. Building cycle lanes on side nearby roads means working with the boroughs, and that’s inevitably more difficult and time consuming.

But if the long-term plan is to push cyclists via side roads anyway, it’s questionable whether all this disruption is worth it. A segregated cycle lane that stops without warning and leaves you fighting for space with three lanes of buses, lorries, and cabs is a cycle lane that’s of no use at all.

Jonn Elledge was founding editor of CityMetric. He is on Twitter as @jonnelledge and on Facebook as JonnElledgeWrites.