Tag Archives: IAU

Wasp Planets… as Pokemon: A Chrome App

Scanning the list of new planets WASP has found (a large proportion of which are unpublished), it occurred to me that we are getting very close to 150 planets! It also occurred to me while making the Underground Map of Wasp planets (see next post), that our planet names are really boring.

An exoplanet Transit

So, to both fix the naming problem and celebrate the number of WASP planets, I have decided to turn all Wasp planets into the 150 original Pokemon! Working on Wasp-12 b? Nope – You’re working on Butterfree. Wasp-6? Charizard. Wasp-64? Machoke. Wasp-135 b? Jolteon. IAU eat you heart out…

And while I know this will be a difficult thing to achieve politically, we can at least achieve it indirectly, thanks to the magic of Chrome Apps! Unfortunately I don’t have time to make a completely self-contained app for this, but here’s 4 quick steps to follow to add a bit of early-naughties humour to exoplanet science:

  1. Open Chrome and go here to download ‘WordReplacer’
  2. Find Chrome’s ‘Settings’ menu, then the ‘Extensions’ tab, then find ‘Word Replacer’ and click on options.
  3. Open up this pastebin in another tab, and copy the text (it’s easiest from the “Raw paste data” box at the bottom). [BONUS: Kepler names replaced by 1920s baby names with this pastebin]
  4. Back on Word Replacer, click ‘Import’ and paste the text in. Finally, click Save Settings and you’re good to go!

Then you get to enjoy lists such as this; or papers such as this: PokemonPlanets PokemonPlanets2       . . . . EDIT: Bonus update. Now replace all Kepler planet names with the top 2000 baby names… from the 1920s! Say hello to planets Gertrude (Kepler-127), Salvatore (312) and Ruth (Kepler-11). Use this pastebin in place of the WASP-only one above to get both!

Rogue Planet or Failed Star?

It sounds like an interstellar sob story: a lonely planet expelled from it’s Solar System at a young age and forced to wander the galaxy alone. But what makes us so sure such objects are even planets, and does their discovery change how we view the universe?


More than 2 years ago, the PanSTARRS telescope on Hawaii captured a dim red blob on its sensitive cameras. However, the importance of this dot was overlooked and the image was added to a 4000TB database of images, where the evidence of this discovery sat in wait. More than 18 months later it was rediscovered by Michael Liu and colleagues at the University of Hawaii who decided to take a closer look.

They found the point of light, now named PSO J318.5-22, to be an extremely red object only 80 light years away and floating freely through space. By studying the colours of the object they were able to determine a surface temperature of only 1160K and a mass only 6.5 times more than Jupiter . To begin nuclear fusion in the centre of a star, it needs to be larger than 13 Jupiter masses, making this object far too cold and small to be a normal star.

It is not the first ‘Rogue planet’ to have been discovered, with a further 4 objects found by similar sky surveys. These all have sizes in the region between large Gas Giant Planets (5Mjup) and small Dwarf stars (15Mjup). In all cases, including with PSO J318.5-22, these size estimates are extremely unreliable with a margin for error of up to 5Mjup either way.


Logic might suggest that, if a ball of gas is too small to be a star, it must be a planet. However the boundary between the smallest stars and the largest planets is a very blurred one. The astronomers involved were careful not to call their discovery a planet, instead giving it the label of “late-L dwarf”, similar to a Brown Dwarf (right). That being said, similar sized objects such as the gas giants around HR8799 have made it into the nearly 1000-strong catalogue of exoplanets. So what makes this a special case?

One reason is the loneliness of PSO J318.5-22. In 2006 the International Astronomical Union met for a now-infamous meeting to demote Pluto to the diminutive status of dwarf planet. This decision also came with a new set of definitions for what it takes for an object to be considered a planet. Not surprisingly, clause number one was: it must orbit a star.

While the recent discovery falls down on this particular point, many commentators have pointed out that PSO J318.5-22 may well have been formed around a star before being expelled. This is not as far-fetched as it might sound; many models of planet-star interactions in complicated two-star systems have shown that planets could be tossed around like billiard balls.


However, there is another option: PSO J318.5-22 could have formed in a collapsing cloud of gas and dust just like every other star in the universe. Such a scenario would completely exclude it from the definition of planet, making it more ‘Failed Star’ than ‘super-Jupiter’. Without further investigations it is impossible to know the answer.

In many ways the question of formation is unimportant: without a star to orbit, these are not planets. It may be a case of  soul-searching but, while the slow cooling of PSO J318.5-22 from warm proto-star to a lifeless ball of gas might interest a handful of stellar physicists, it is conventional planets like our own that can really challenge the understanding of our place in the universe.

Read the paper here on ArXiv