From Dwarf Planets to Hobbit Galaxies

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dwarf galaxyI learned from an article in New Scientist by David Shiga that there have been recently found four more small satellite galaxies of our Milky Way galaxy.

The satellites are dwarf galaxies a few hundred to a few thousand light years across. The tiny galaxies are thought to be the building blocks of large galaxies, such as our own Milky Way – which is about 100,000 light years wide.

As you may know, we’ve known for some time that there have been such satellites (the number knwon has gone from 10 to 20 in the last two years, and some models expect as many as 50), but the small ones are very hard to detect. How do you distinguish them from other stars in the way? As part of the Sloan Digital Sky Survey (SDSS), the researchers have been looking for….

the particular types of stars expected to lie in dwarf galaxies, then detect the dwarfs as slight “overdensities” in these types of stars – patches of the sky where there are more of the stars than in surrounding areas.

The Cambridge team named them after the constellations in which they were found:

[…] Coma Berenices, Canes Venatici II, Hercules, and Leo IV, all of them lie between roughly 100,000 and 500,000 light years from Earth.

[…]The largest and smallest are Hercules and Coma Berenices, which are about 1000 and 200 light years across, respectively. Like most of the other dwarfs discovered by SDSS, the new finds are much smaller and fainter than the 10 dwarfs that were known previously, [Vasily] Belokurov [the team leader] says. “They should not really be called dwarfs – they are more like hobbits,” he told New Scientist.

Hobbits. Right. Does that make the Milky Way a Cave Troll? Or maybe a Numenorian? (Picture above is one of them. This one’s Farmer Maggot, I think. They’re not as Click to continue reading this post →

Mama Said There’d Be Days Like This

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Oh Boy. So it started this morning with me making some plans to do things on the bike, starting with a visit to the Hollywood Farmer’s market to get some supplies (especially some more superstring beans, which are delicious!) and meet a friend. Idea would be then to -after excellent tamales for lunch from my favourite stand, of course- visit a couple other places, such as a bike store in West Hollywood to get some equipment for my friend’s bike, and then maybe over to the Sunset Junction street fair (you might remember my blogging about it last year), to par-tay. Then I’d go home and work.

Bad thing number 1:

  • Halfway to the middle of Hollywood on the way to the market: Catastrophic puncture. Flat tyre. Guess what? Puncture repair kit I carry around with me all the time is of course in my other bag, not the one I use for market. Sigh. So after wheeling the bike all the way to the market (I could have folded it up and taken it onto a bus or train, but I was halfway there and already late and did not want to wait for either), fun, shopping, and tamales were had, which was good. Could not do the other bike things, so I then wheeled bike to the subway, folded it and took it on a train to my ‘hood, then wheeled it home at other end, which all took a while. Actually, wheeling with shopping in its bag is a great way to get the shopping home and see what’s going on in the ‘hood, which I like to do from time to time, so not so bad.

    As this is only the second problem I’ve had with this bike in almost 18 months of cycling it around the city, I decided (yeah, I know!) to take a commemorative picture of the sad scene:

    flat brompton tyre

But by then I’d lost a lot of time and I’m supposed to be working on writing a paper today. So I decided to pass on the Sunset junction activities (I can hear them from my place a bit, and I encouraged some of my students to go, so I can sort of live vicariously -even though I know they won’t go) and work on the paper. I want to give a draft to some of those students for them to get up to speed on the idea, and once the week starts, I don’t expect to get much time to work on this sort of thing before next weekend.

So okay, no par-tay-ing this afternoon. But first I’d better get bike back to functionality for work tomorrow.

Bad thing number 2:

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Blue Asymmetry

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blue flowers
I’ve temporarily forgotten the name of this beautiful flower. I’ll let you know when I recall it. [Update: Athena worked it out and reminded me….Scaveola, or fan flower] Its blue is more dramatic than the camera has captured. It nods somewhat more to purple than is suggested here. It grows reasonably fast and close to the ground, and is drought tolerant, so I used them as a quick ground cover to repopulate a part of the garden. They’ve done very well since I planted them in the Spring.

blue flower closeupOne thing I love about them is the asymmetry of each individual flower. Look closely (click on left image) and you’ll see that there are five petals on each, but the five are on only half the flower. Very asymmetric on that scale, but on a slightly larger scale, symmetry is restored by arranging a five of these “half-flowers” around a central leaf cluster to make a sort of larger, symmetric super-flower.

Very elegant.

-cvj

A Glimmer of Hope for Pluto?

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So despite the announcement yesterday, reliable sources tell me that some members of the astronomy community are hoping that there is still maybe a small window of opportunity for Pluto.

Some members of the community are preparing a petition which protests the IAU planet definition! They don’t agree with the decision, and point out that a rather small percentage of the astronomical community actually voted at the Prague IAU. They give the following additional reasons for their questioning of the decision:

They say that the community voted….

… for a definition of ‘planet’ that uses dynamics (location) rather than intrinsic properties to decide if an object is or is not a planet. This result is counter to other classification schemes in astronomy (e.g., stars, galaxies, nebulae, even asteroids) in which dynamical context does not play a controlling role. Furthermore, it produces results that are incongruous and cannot be extended within our own solar system or to extra-solar planetary systems without producing immediate results that are patently absurd: e.g., a Neptune-sized object discovered beyond 150 AU could not be a planet, the presence of an Earth orbiting its star between a Jupiter and a Saturn would mean the Earth could not be considered a planet since it could not clear its “neighborhood”. This definition also excludes Pluto from planethood in our solar system, something that is both scientifically questionable and publicly problematic. Both Pluto and a distant Neptune would be classified as a “dwarf planet”, which is not to be considered a subcategory of “planet”.

The petition is to be among the community only, so I will not give you details about how to sign it. Also, I don’t know if I have permission to reveal the names of the people who put forward the petition, so I will not do that, at least until I know more.

This is rather unexpected and quite interesting, I hope you agree.

-cvj

Spinach Blogging

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I learned a new term from a producer at a television studio the other day (in a context I do not know if I’m allowed to blog about yet): “Spinach TV”. I love it. This is a term expressing the idea of television programming that is supposed to be “good for you” since it is educational in some way. Some of us are doing this sort of thing in the blogging world, for better or worse. See my about page.

With that in mind, I’d like to offer some words about this week’s science coverage of the two big Astronomy/Astrophysics stories. I’ve heard the issue raised a number of times today (including by my colleague Sean over on CV) that it is somehow to be thought of as a bad thing that there’s more coverage in the press of the Pluto demotion than there is of the new results giving new direct evidence of Dark Matter. The former is supposed to be all about the politics of science while the latter is supposed to be covered more since it is a profound new result.

With all due respect to my friends and colleagues who have expressed that opinion, I would say that such a view is somewhat short-sighted and has more than a whiff of elitism about it. They’re just missing the big picture. I completely agree that the Dark Matter result is vastly more important new science than the simple fact of Pluto’s demotion, but from the perspective of science education, the value of the Pluto coverage is immensely important, and maybe at least as important as the Dark Matter coverage. I can think of several reasons, and here are some:

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Bleep Bleep Yet Again

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If, like I am, you’re tired of people getting ensnared by the nonsense in the “What the Bleep…” movie, and asking you to explain it….(I scared myself just now by looking at the technorati tags for and …yikes)… please please help out Jennifer Saylor, a blogger who is a freelance writer with a passion for science. She wrote a post about the movie recently, which you can read here. She let me (and my colleagues over on CV) know about it, and -more importantly- let us know that she’d like to do something more than just blog about it expressing her annoyance. Let me reproduce some of her email:

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So Do We Need a New Planetary Mnemonic?

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So you’ll recall that when we thought we had twelve planets we started trying to think of new mnemonics to help people remember the planets’ ordering.

For example, from Yvette:

My Very Educated Mother Can’t Justify Someone Using New Planetary Conventions… oh no, they haven’t named the last one yet!!!

Or from Amara’s friend Damien Broderick:

My very eccentric mother’s cook just served us nine pastry coated xylophones

(On the assumption that the last planet would be named Xena.)

Or from astromcnaught:

My View Embraces Moving Classifications, Just Stop Uncovering New Planets Called 2003 UB313

Or from Alan Hamilton (via Robert Greenham):

Most Victorian Euphoniums Make Cats Jump Suddenly Unless Neighbours Play Calming Xylophones.

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Eight Planets!

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Ok… Let’s try this again shall we?

It’s official! There are eight planets in our solar system. The vote has taken place. Last week’s proposals have been rejected. Pluto has been demoted, apparently.

They were voting on the following (I got this here):

1) A planet1 is a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (c) has cleared the neighbourhood around its orbit.

(2) A dwarf planet is a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape2, (c) has not cleared the neighbourhood around its orbit, and (d) is not a satellite.

(3) All other objects3 orbiting the Sun shall be referred to collectively as “Small Solar System Bodies”.

1The eight planets are: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.
2An IAU process will be established to assign borderline objects into either dwarf planet and other categories.
3These currently include most of the Solar System asteroids, most Trans-Neptunian Objects (TNOs), comets, and other small bodies.

That was resolution 5A, and then there is 5B:

Insert the word “classical” before the word “planet” in Resolution 5A, Section (1), and footnote 1. Thus reading:

(1) A classical planet1 is a celestial body . . .

And then the Pluto-specific resolutions (actually, 5B seems to lay the groundwork of the attempt to save Pluto):

RESOLUTION 6A
The IAU further resolves:

Pluto is a dwarf planet by the above definition and is recognized as the prototype of a new category of trans-Neptunian objects.

RESOLUTION 6B
The following sentence is added to Resolution 6A:

This category is to be called “plutonian objects.”

Anyway, from what I heard, looks like these attempts to keep it have been rejected – those last few resolutions were voted down – and Pluto has been given the chop.

More later…

[Update: BBC story on it here.]

-cvj

It’s Not Over ‘Til It’s Over

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The saga continues. Nobody yet knows how many planets we have. There has been fierce argument at the International Astronomical Union. As a result, the definitions of last week have been revised. “Pluton” has been discarded as a term (partly because of the clash with a geological term, a clash which was also swiftly noted by one of Asymptotia’s readers), and the vote is very soon.

IAU meeting photo

Pluto and all the loveable little bodies might now in trouble because a revision to the definition says that a planet must be the “dominant body” in its orbital zone, clearing out any little neighbours. New Scientist’s website reports that

Pluto does not qualify because its orbit crosses that of the vastly larger Neptune.

Quoting further:

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International Cooperation Can Work

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nasa ozone hole pictureApparently the hole in the ozone layer above Antartica is stabilizing. Some of you will remember the late 80s, when the hole was discussed a lot in the popular press. It was a huge problem. The hole we made meant that we were losing our protection from the sun’s ultraviolet rays. We identified that chloroflourocarbons -CFCs- which at the time were used everywhere (such as propellants in aerosol cans, refrigerator coolants) were the chief ozone-depleting substances that we produced.

What did we do? We sat down in Montreal and decided -as a global society- to change our behaviour. International agreements were arrived at to stop producing CFCs (and a range of other related molecules), to serve the greater good.

It seems to have worked. See the article I spotted on the BBC’s news site. Quoting:

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Why I’m Sometimes Sure We’re Doomed

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Some days I’m optimistic, and I think we’ll change our behaviour in time. We’ll be able to stop destroying our environment quite so recklessly. We’ll stop our dependence on oil and other fossil fuels. We’ll stop fighting ridiculous wars over such fuels…. etc.

Other days, stuff like this happens, and I think “We’re Doomed”.

The scene: Two Fridays ago at Aspen airport. I was there to pick up a rental car that I had ordered over the web. It was needed for a trip I will tell you about. Of course, I had booked for a compact car, and was hoping to get one.

So I filled in the paperwork as usual, checking the boxes, declining the insurance (since I have my own), etc. The usual drill. Then the agent gave me one other form to sign which was weird. It is an agreement to accept a financial penalty if I brought back the car within two hours of renting it. I asked about this and he mumbled something about breach of contract, etc, etc. After giving him a hard stare, I thought nothing more of it.

Transactions with paper done with, the agent smiled at me and handed me the keys. Now remembering what just took place (see end of previous paragraph), observe what he said:

“Well, we don’t have any cars left sir, so we’re giving you a free upgrade to a Chevy Humongous. It is an SUV”.

“But I don’t want an SUV, Chevy Humongous or otherwise”.

He looked at me like I’m nuts.

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MOND Laid to Rest?

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Well, the press conference I told you about has happened! This is so exciting! There’s new and very direct proof from observations of the Bullet Cluster with the Chandra X-ray Observatory that Dark Matter really exists.

Bullet Cluster Composite

So the need to make modifications to how gravity works on large scales in order to explain observations seems to be something we can put aside for now.

Your mission: Go to the press release website for more information, and lovely Click to continue reading this post →

More Scenes From the Storm in a Teacup, I

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Aaron Bergman has written an extensive review of Peter Woit’s attack-book on string theory. I’ll let you read the thoughtfully written 11-page pdf document linked there. I think that Aaron deserves some sort of medal or other award for making the effort. Peter responded here.

Note from the title that this post is part I of II. Part I was to be a quick rundown of my thoughts on the recent Science Friday program featuring a head-to-head between Brian Greene and Lee Smolin over string theory research. I never finished writing it. I’ll try again in a day or two, and make it part II of this.

You can pretty much tell from the title of this post what I’m going to say. This is all just mostly media-inflated nonsense, which will continue for some time. In case it is not obvious why, I’ll summarise my reasons for saying this (again) in that post.

Summer has ended for me. Tons of stuff to do during first day of semester tomorrow.

-cvj

(Spotted at Uncertain Principles.)

Uncertainty

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Below (nearer the end of this post) is the description of the “Uncertainty” event (Thursday 31st August, 7:00pm, USC’s Annenberg auditorium; much more here) part of USC’s Visions and Voices program I told you about in the previous post.

These are, as I said, events that build upon the Categorically Not! series held at Santa Monica arts studios on Sundays, and about which I have blogged extensively on Cosmic Variance (see some recent descriptions here and here). The old Categorically Not! series will not stop. The Santa Monica series will continue, but there will be some gaps to accommodate the USC events. We hope that the regular Santa Monica crowd will make the short trip across the city to USC on those nights. For more information on all Categorically Not! – type events, visit the Categorically Not! website.

We will start on the USC campus -in the Visions and Voices program- with Uncertainty, and we will do this theme twice this semester. We did this theme before, actually (we had K.C. Cole, Jonathan Kirsch, and Julia Sweeney) and it was very successful. We were planning to redo this first event with the same presenters, but at the time of planning, Julia (who did extracts from her monologue/show “Letting Go of God” (which you must see if it comes to a theatre anywhere near you)) was thinking of leaving LA for a bit -nooooo!- to go away for a year to New York to do her show there. So we modified things and added a different component – from actress Chloe Webb instead (which will no doubt also be thought-provoking, entertaining, and funny …see below). (I’ve since heard from Julia that her plans have changed and she’ll be staying in LA -hurrah!- and so I’m already thinking of some ways of collaborating with her on arts-meets-science related projects in the near future, which I’ll probably tell you about – as soon as there is something to tell.)

Why redo the theme? Why twice? What other themes will we do there? Have a read of the Science and Serendipity blurb at this link to get an idea of what we had in mind. An extract:

Science, Serendipity and the Search for Truth puts science on stage in an informal series of conversations and performances alongside music, theater, journalism, religion, film, dance and other disciplines to see what serendipitous connections might bubble up. The informality of the presentations and discussions will encourage intellectual risk-taking–both on the part of the presenters and the audience. People will feel free to “play” with ideas in any way they like–falling on their faces if need be, rather than bending over backwards to please some arbitrary convention. Nothing will be rigged, staged, hyped or in any way polished and sanitized or overly practiced. Because of this, we have reason to believe that real discoveries can be made.

“Uncertainty” is just an excellent theme for this, and we’ll use it this Fall semester. “Point of View” is also an excellent theme, and we’ll use that in the Spring Semester. We did that latter theme before too. We’ll get a chance to revisit both with performances and presentations similar to the ones done before, and then we and the participants will look at themes all over again with a fresh set of performances and presentations, having had time to discuss everything over the intervening weeks (maybe on this blog if you’re game?). It should be fun and instructive, I hope you agree.

Here is the blurb for the first Uncertainty event:
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