24 August 2006

Pluto Demoted!

And just when I was getting used to the old proposed definition, it's been modified and voted on (237 for, 157 against, 30 abstain) to
[A planet is] a celestial body that is in orbit around the sun, has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a ... nearly round shape, and has cleared the neighborhood around its orbit.

So we now have 8 planets, MVEMJSUN, a class of "dwarf planets" (which I think are anything round but not unique in orbit), and "small solar system bodies" (anything else).

And to paraphrase my friend Foxtrot, despite what CNN says, this will not CAN not affect the New Horizons mission. It's already been launched.

ETA: Ugh. And despite what else CNN says, Ceres was never a planet. it was temporarily incorrectly called one when we didn't have an official definition. This (BBC) may be a better article.

ETAA: I'm liking this definition less and less. According to CNN, "Pluto is automatically disqualified because its oblong orbit overlaps with Neptune's." Well then, why isn't Neptune disqualified b/c it didn't clear out Pluto, et al.? It could be that Pluto's orbit's different enough that we can let it slide for Neptune's definition and then it's actually Charon and the Plutinos (ooh, a good band name!) that disqualif Pluto. But then what about Jupiter and its Trojan asteroids?

21 August 2006

Seven signs of bogus science

As usual pointed out to me by the inimitable resurrected Sclerotic Rings, it's a list of the seven signs of bogus science! They're not meant to be a fail-safe set of criteria on which to judge what's good science and what isn't, just a starting point.

20 August 2006

Planetary changes

People keep coming up with more interesting thought experiments to test the proposed definition of planet. This one, the changing orbit of the Moon. The Earth-Moon barycenter (center of mass) is currently within the Earth, however, the Moon is drifting away slowly, and in a few billion years, the Moon will be far enough that the barycenter will be outside the Earth's surface. Should that happen before the red giant Sun engulfs us, we'll have to have a Moon-Planet birthday party. Though, when the exact moment that happens is may depend upon things like if it's over Mt Everest or an ocean trench, and do we count the oceans and air and such as part of the Earth?

And what if there's a binary planet system w/ really eccentric orbits, or a mutliple planet system, then we might have the barycenter sometimes within a planet, and sometimes not, so the others would sometimes be moons and sometimes planets. Oy!

19 August 2006

Mass Limit for Fusion

Astronomers may have found the lower limit on mass for nuclear fusion, and thus the upper limit for brown dwarfs, BBC reports. Unfortunately, they present some new misconceptions in the process - brown dwarfs aren't "dead" stars, they're stars that were never born, or perhaps overweight gas giants. But they never did have hydrogen fusion in the core, so they never stopped.

What Richer, et al., actually did was turn the HST towards a globular cluster in our Milky Way and take a 5-day exposure. (In reality they took multiple shorter exposures that were combined into one long one - no one takes a single exposure that long in case something goes wrong and because the tracking isn't perfect even on the HST.) In the image, the faintest stars they could see corresponded to 8.3% of the Sun's mass. If fainter stars existed Hubble would've been able to pick them up, but the article isn't on astro-ph and Science magazine restricts (free) access to the abstract only. If anyone has a subscription and can find the mass-equivalent detection limit of Hubble in the full article, I'd love to know.

Light Pollution makes BBC News

Read the article. Then check out the International Dark Sky association webpage.


It's amusing what you find when you do a search on your username. A year later, I found Inner Girl's link to me. :-P Thanks!


Reminiscent of the Clickworkers project, Stardust@Home uses human eyes to find specks of dust and cometary debris embedded in a piece of aerogel brought back from the Stardust space mission. Funny thing is, years ago as an undergrad one of my classmates gave a talk on his summer research project at NASA working on developing the aerogel...

Thanks to ian-atkin.net for the link/reminder to put something about this up.

Below are the contents of two previous comments to this post; the original posts themselves were deleted (and further commenting prohibited) on request of the first author due to their name being included.

Anonymous said...

Hi, my name is ********.

sorry if I am wrong, but is this NASA that is wanting volunteers to search through the pictures? If they spent so much money on all the equipment, I think they would have planned for the laboratory work as well, unless they are using volunteers to discover the least important (unless unkwonwn) part of the aerogel.

Instead of using your time searching through pictures, look up some NASA UFO videos on youtube.com or video.google.com . Wouldn't it be better instead to ask NASA why they don't do live broadcasts anymore, and disclose all information they know of regarding the kind of objects or "UFOS" they almost certainly know about.
Either that or there so many people out there trying to mislead others for almost no apparent reason.
2:39 AM, August 20, 2006

zandperl said...


The reason they need volunteers has three parts to it: (1) it is a task that computers are not yet able to do, and (2) it will take so many man-hours that it would take years with their current staff, and (3) if UC Berkeley and NASA were to hire people to work on it, they'd go bankrupt before they found anything.

As for UFOs, I personally don't believe they exist, and I think that the people who do think they exist want to believe and so are deceiving themselves when they see something they think is evidence of a UFO.
11:14 AM, August 20, 2006


Ugh. The FDA has approved use of a bacteriocidal virus on processed meats. These bacteriophages kill listeria monocyogenes, which is responsible for up to 500 deaths in the US annually. The virus only attacks that type of bacteria, but it's still a scary method of control. I can just picture a combination of mutations, where the bacteria become resistant to the virus, and the virus also mutate to prey upon humans. I'm thinking organic meat's sounding better and better.

18 August 2006



As you've undoubtedly already read elsewhere by now, a subcommittee of the International Astronomical Union has proposed a definition for planet. I had it delivered to my flap-step while I was camping in Acadia National Park the past week.

The part of "IAU Resolution 5 for GA-XXVI" that describes the planet definition, states "A planet is a celestial body that (a) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (b) is in orbit around a star, and is neither a star nor a satellite of a planet."

The first condition sets a lower limit, it's meant to include objects. It could do with a more quantitative description, but perhaps the words are sufficient if I knew my gravitational fluid dynamics better. If it were all there were though, we would have to include the Moon, Io, Europa, Callisto, Ganymede, Titan, Mimas, Triton, Encealdus, and countless others I can't recall. So we introduce the second condition to limit it: must be orbiting a star. Embedded within that definition is the implication that if two (or more) bodies orbit each other, we must look at the barycenter (center of mass) of the pair - if it is within one body, that is the planet and the other is the moon. If, as in the case of Pluto and Charon, it is between the two bodies, then they are both planets.

There are of course criticisms or quirks of the definition, though I am admittedly beginning to warm to it. There is no third condition for when mulitiple objects are in similar orbits, and this allows mostly round asteroid Ceres to remain a planet. 2003 UB313 (provisionally dubbed "Xena," though it will be officially renamed something else by the IAU later) is bigger than Pluto, and therefore definitely massive enough to be round. Quaoar and Sedna are smaller than Pluto, so we're reserving judgement for now, but we're left with 12 planets in the Solar System if the definition passes. The "planemos" discovered a couple weeks ago would not be planets, as they are not orbiting a star.

There's also an additional clause for concern.

The IAU draft Resolution also defines a new category of planet for official use: "pluton". Plutons are distinguished from classical planets in that they reside in orbits around the Sun that take longer than 200 years to complete (i.e. they orbit beyond Neptune). Plutons typically have orbits that are highly tilted with respect to the classical planets (technically referred to as a large orbital inclination). Plutons also typically have orbits that are far from being perfectly circular (technically referred to as having a large orbital eccentricity). All of these distinguishing characteristics for plutons are scientifically interesting in that they suggest a different origin from the classical planets.

The description of plutons in terms of orbital characteristics rubs me the wrong way. However, I could easily see redefining it to fit the current model of terrestrial and jovian planets. The three sub-categories would then be:
  • Terrestrial / Rocky - Mercury, Venus, Earth, Ceres. These planets have densities of 3-5 g/cm^3 and are primarily composed of rocky material (carbon/silicon solids, and may contain liquid metal cores. Asteroids, the Moon, and Titan fit these characteristics though they are not planets.

  • Jovian / Gas giants - Jupiter, Saturn, Uranus, Neptune. These planets have densities typically less than 2 g/cm^3 and are primarily composed of atomic hydrogen gas, with trace amounts of other gaseous molecules such as methane. The inner layers transition into liquids due to the intense pressure. Gas giants are NOT undergoing nuclear fusion of either hydrogen or deuterium. Brown dwarfs do not fit into this category, however I believe all extrasolar planets discovered to date do.

  • Plutino / Icy - Pluto, Charon, 2003 UB313. Lastly these planets will have a density of roughly 1-3 g/cm^3, and their composition will be predominantly ice - water ice, carbon dioxide ice ("dry ice"), methane ice, and so on. They may have some rocky content or core, but not a significant portion of their composition. Quaoar and Sedna will count in this category if they turn out to be spherical. Europa, Ganymede, and Callisto would be counted if they weren't orbiting Jupiter.

ETA: The BBC says we should keep our eyes on three more asteroids, Vesta, Pallas and Hygiea, that are at the borderline of mass/roundness for whether they count as planets.

Anonymity Bubble

Something's come up that I fully expect will soon burst my bubble of anonymity - that is, the boundary that I've been trying to maintain between my professional and blog lives. I'm apprehensive that something unprofessional will leak to my job, for example I might've made a comment about students on here, which is against FERPA, and my employer wouldn't like that. I don't mind if I have posts about my religion (or lack thereof), or occasional mild curses, but anything worse than that trickling out gets me uncomfortable.

If any readers have free time and are bored, I'd appreciate if you poked thru my archives and left a comment on any post that seems it might be a bit too risque for me to want it connected to my real name. Thanks!

01 August 2006

March of the Prostitutes

I thought it was intriguing when I learned about all the gay, bi, and pedophile penguins out there, and depressing when I saw what horrible parents they were, but it's a straight up shocker to learn they're also whores!

The researchers kept their eyes open for more cases of penguin prostitution, and they observed a total of ten over three breeding seasons.

In each case, a female penguin left her mate and made her way to a single male at his nest. She stood nearby and gazed at him. When he gave her a sidelong glance and bowed his head, she followed suit. The hopeful male then stepped off his platform of stones, allowing her to waddle on. Leaving no uncertainty about what she was there for, she lay face down on the nest, and the male mounted and mated with her. Afterward, she got up, picked up a stone with her beak, and without further ado, went back to her own nest. In half of the cases, the female returned to the same single male for a second stone, although they did not mate again. In one instance, a female made off with a total of ten stones.

How to Clean your CPU

(Other than by using the dishwasher.)

A webcomics wife's blog that I read had a question about a noisy computer fan today, and since she's really nice, I wrote a description of how to open up your CPU and clean it out in case she didn't already know how. I thought I'd repost the comment here as a resource for anyone else. Others had previously commented on using a can of air to blow out any dust.

Ditto on the can of air. You'd be shocked how much gunk's in there. If you're doing it yourself and haven't before, opening up and shutting back up a computer's not much harder than filling your car's gas tank, probably on par with checking your tire pressure and oil level. It's perfectly safe so you 99.99% chance don't need to back anything up. If you've done this sorta thing before, or if you can figure it out on your own, ignore the rest of this comment. :)

Shut down the computer and unplug everything from the CPU (I usually start with the power cord, but I'm probably paranoid). Place it gently (don't drag or drop) on the floor in an area you don't mind getting dusty. If there's anything caked on the outside from animals or kids, now's a good time to get it - use alcohol based wipes. If you or any of the kids have asthma, consider wearing a dust mask before opening the CPU.

Inspect the back and sides of the case looking for a piece you can take off. There may be up to 4 screws holding on a side or top panel, they may need a screwdriver, wrench, or just your fingers; there may be some tabs you have to push while sliding a side of the case; you may have just one side come off, or it may be two sides and the top. Sorry I can't be more specific, they're all different. If you can't figure it out, take pictures from all sides (reassemble the computer) and post and we'll figure it out for you.

Once you're inside the guts of the computer, do NOT use water, and if you have to touch any of the circuit boards do so on the edges, gently. I take a can of air to the whole thing, getting out the big chunks first, then working methodically from the fans on down, getting every side of every item in there. Expect to use a half a can of air if you haven't been in there in a year. If there've been any other problems, you can also reseat and wires with plugs and cards that go into the motherboard. First time I did this I took a sharpie and put little notes to myself along the case when I figured out what certain parts of did, so when I had to change a hard drive later it was faster for me to find which thing it was.

Put CPU back together the same way you took it apart - things should only fit together one way, and don't force anything if you're uncertain. Plug things back in to the CPU - again, everything should fit in only one spot with the possible exceptions of phone modem wires (if it doesn't work one way, switch it), speaker wires (ditto), mouse/keyboard (look for colors or pictures), and USB wires (doesn't matter, your computer will figure it out). Again, I do power cord last b/c I'd rather safe than sorry.

Once you're done, turn it on and see what happens! Oh, and clean up the dust that's now everywhere. Good luck. :)

Science Quiz?

Someone explain to me what half of these questions have to do with science.