Friday, September 01, 2006

Pluto is not a planet, so deal with it!


Pluto's demotion from planet to minor planet is not a big deal, but a lot of people are making fools of themselves over it. Earth to Yuggoth: Get OVER it!

The small blurry pictures at the top left of this image are Hubble images of pluto. The larger smoother nicer looking images are a model fit to the data.


Its been clear for a long time that Pluto was not like the other planets, and including it was pushing the definition into dangerously ambiguous waters. The was a lot of discussion and finally a vote at the Prague general assembly of the IAU (the only organization allowed to officially name astronomical bodies, by the way) and that is that. So what is all this fuss?



Let start with the supposed hijacking of the vote.

He [Owen Gingerich] added: "There were 2,700 astronomers in Prague during that 10-day period. But only 10% of them voted this afternoon. Those who disagreed and were determined to block the other resolution showed up in larger numbers than those who felt 'oh well, this is just one of those things the IAU is working on'."

...

Professor Gingerich, who had to return home to the US and therefore could not vote himself, said he would like to see electronic ballots introduced in future.

Alan Stern agreed: "I was not allowed to vote because I was not in a room in Prague on Thursday 24th. Of 10,000 astronomers, 4% were in that room - you can't even claim consensus.

So the vote is somehow not valid because Stern and Gingerich all the others didn't bother turning up to vote, a vote they knew when and where was going to occur. Oh puuuullleeease.



If couldn't attend then that is tough. Valid reasons for complaining about a vote result are fraud, or disenfranchisement, but lets face it: any astronomer who wanted to go could have gone.



Secondly there is this (fine bit of journalism: a classic "some say") from the BBC article linked to above.


A fierce backlash has begun against the decision by astronomers to strip Pluto of its status as a planet.

Where is this backlash - most of it that I've seen is purely media-driven self-referential 24-hour cable news talking head nonsense. The "I was taught its a planet in school, so how dare you change it" mentality.



Yeah, so the leader of the New Horizons mission to Pluto is pissed [disclaimer: the Applied Physics Lab is somehow vaguely connected with JHU where I am currently employed]. That's hardly surprising (and it doesn't mean Pluto isn't interesting, or that his mission will suddenly disappear on route), but that is one person. Personally all the professional astronomers I spoken to about seem pleased Pluto has been demoted. That's 3-1. By MSM rules there should be an article "Astronomers overwhelming mandate Pluto's destruction" or something ;).



Anyway, in more petty silliness 300 or so astronomers have signed a petition saying they won't use the new IAU definition. If you cared that much then why did n't you bother going to the damn IAU and voting on a definition you liked then, instead of creating a bunch of bad publicity for astronomy?



The newly-adopted definition of planet has it own weaknesses. But so will any definition, because there really isn't a physical cut-off that can be made with non-fusion-burning astronomical objects planets, asteroids, comets. What should not be ignored in all this unnecessary fuss is that the new definition is BETTER than the old one. And that is the way science works, by incremental improvements. Don't expect a PERFECT solution.




And as for naming the icy minor planets "Plutons" - well, it was a nice try, I like the idea of having a new name (I would have preferred Yuggoths). This was one of the suggestions. A bit of background from the Nature web site we have this article (this is from before the IAU-vote).


On 16 August the International Astronomical Union (IAU) floated a proposal for a definition of the word 'planet', in part to end the confusion about whether Pluto is a planet or not. But their solution, which assigns Pluto and its neighbor's to a subset of planets called 'Plutons', is so far just creating more confusion and angst.



Scientists have pointed out that the word 'pluton' is already taken by geology, making at least one geologist hopping mad. Furthermore, astronomers have argued that the definition just doesn't fit with their intuitive sense of what a planet is — leading, already, to a second proposed definition. The confusion will probably continue until this Thursday, at least, when IAU members will put the proposals to a vote.


IANAG (I am not a geologist) but I knew pluton was a rather widely-used geological term. Apparently some exalted ones did not:



Owen Gingerich, an astronomer at Harvard University in Cambridge, Massachusetts, and chair of the IAU committee that created the definition, says that they were aware of its usage amongst geologists, but unaware of its importance to the field. "Since the term is not in the MS Word or the WordPerfect spell checkers, we thought it was not that common," Gingerich wrote in an e-mail to news@nature.com. The geologic definition of the word does appear in common dictionaries, including the Oxford English.
I hate to point out to Prof Gingerich that almost all astronomical terms are not to be found in dictionaries, even good ones like the OED, let alone bad ones like MS word's atrocious spellchecker. This is not a good excuse for messing up with pluton.



You can always tell when an astronomer has ceased doing astrophysics research and has become more of an administrator or retiree, and that is when they start using Microsoft products like Word all the time instead of LaTeX running on a *nix system. I am not being snide, Gingerich is an senior astronomer emeritus, and his primary current interests are the history of astronomy (for which he is well known), see his bio here. Computer whizz he may not be, but someone please show him wikipedia!

Friday cat blogging



Macio in a playful mood.

Thursday, August 31, 2006

Oh the huge manatee!



I know - this is not astronomy but I find it interesting and suddenly there is a lot of manatee-related news, so its going in.



Long story short - manatees, short-sighted but maybe surprisingly smart, though why a smart creature would go swimming in the Hudson or to Rhode Island I don't know.




Apologies to Skatje (PZ's daughter) for stealing bandwidth via the huge manatee pic I naughtily cross-linked to.

Wednesday, August 30, 2006

Picture of the week: NGC 4945



Well, I'm back after a long hiatus due to writing up my XMM-Newton observation of the (supposed) Seyfert 2 galaxy NGC 6810. Various interesting things have happened in the mean time that I mean to post about, both scientific and political, but that will have to wait. In the mean time here is a pretty picture of the very odd galaxy NGC 4945.



As you can see NGC 4945 is a roughly-edge-on spiral galaxy at about 3.7 Mpc distance (~12 million light years), the star-forming spirals arms showing up in blue in this V(isual), B(lue) and U(ultraviolet)-band composite image. Its also rather dusty, with dark or red spots where dust obscuration and reddening is high. I made this image from the Optical Monitor
data from the public XMM-Newton observation.



NGC 4945 is a weird galaxy for a number of reasons. Its one of the 4 brightest extra-galactic infra-red sources in the sky (excluding objects within our Local Group), has a prominent nuclear outflow (e.g. see here, its only ~500 pc [~1500 ly] long), and hosts a very heavily obscured nuclear AGN (i.e. a super-massive black hole weighing somewhere between 1 million and 100 million times the mass of the Sun) that can only be seen at hard X-ray energies (its the brightest source at 100 keV in the sky, if I remember right. At other wavelengths all that dust absorbs the AGN light before it can escape the galaxy). Optically it looks like a starburst, but its hard to work out what fraction of the total emission from the galaxy is starburst-related and what is AGN-related.



All those stars in the image are foreground (i.e. in our Galaxy), and the large number of them tells you (well, tells a professional or amatuer Astronomer anyway) this object is at low galactic latitude (i.e. we're looking through a lot of the Milky Way's disk). This is a pain, as absorption within our Galaxy removes a lot of the soft X-ray emission that could be used to tell us whether NGC 4945
has a galactic-scale wind typical of other starbursts.



All in all, an enigmatic object.