What I Learned Today

Today I attended a fascinating talk by Dr. Michelle Thaller about the Spitzer infra-red telescope and the search for exoplanets. I love hearing about the ongoing discoveries of planets orbiting around other stars. This is cutting-edge observational science! The first exoplanet was detected in 1995; before that, they were only hypothetical.

Spitzer is an IR telescope that orbits the Sun, lagging behind the Earth in its orbit. This lets it observe out away from the IR signal of the Earth and Moon. Dr. Thaller opened the talk with some fun (and fascinating even if you’ve seen an IR camera before!) demos showing how in IR, you can see through some things (black plastic bags) but not others (optically transparent glasses). She noted that the Earth’s atmosphere is opaque in IR, which helps explain both the greenhouse effect and why you need a space-based telescope to observe the universe in IR. More than that, since dust is opaque optically but often transparent in IR, Spitzer has given us our first views deep into the center of our own galaxy (dust blocked optical telescopes’ view into the Milky Way). We subsequently learned that we live in a barred spiral galaxy (previously thought to be just a spiral).

Spitzer doesn’t have the resolution to pick out individual planets orbiting other stars, but it can detect a swept-out gap in a stellar disk that can indicate where a planet has formed. That can guide more detailed investigations for exoplanets, such as astrometry and radial-velocity studies. You can browse a catalog of discovered exoplanets, sorted by their method of discovery or an even more attractive atlas of the planets and their stars. We’re currently up to 326 (from 1, only 13 years ago!). You can follow along with the latest planetary discoveries at PlanetQuest, and even download a desktop/Dashboard widget tracking the exoplanet tally.

The talk was exceedingly well timed. Just yesterday, it was announced that the first ever images of exoplanets had been recorded: Fomalhaut b by Hubble and three planets around HR 8799 by ground-based telescopes Keck and Gemini, using adaptive optics (see more pictures here). The full scientific papers are available here (AAAS subscription needed for full text PDF):

• Optical Images of an Exosolar Planet 25 Light-Years from Earth by Kalas et al.
• Direct Imaging of Multiple Planets Orbiting the Star HR 8799 by Marois et al.

Despite this pile of planetary discoveries, the hunt is still on for “Earth-like” planets: similar to our home world in terms of mass, size, temperature, and atmospheric composition. It’s bound to happen soon!

Today I took my first step towards actually learning to swim. I last had swimming lessons when I was 5 or 6, and it really didn’t take. We moved to the desert right before I turned 7, and since then my “swimming” experience has been limited to treading water, floating on my back, and splashing around. (I first saw the ocean when I was 15, and it terrified me.) I’ve been meaning to remedy this deficiency for a while. The YMCA’s Saturday lessons haven’t worked well with my travel schedule, so I finally called the local Swim America program, which offers lessons at the high school pool. Sadly, they only offer them in the summer, but, I was informed, there are college students who train every evening and are willing to take a break and teach private lessons. So I ended up with my very own instructor! He was absolutely fantastic. First, he didn’t laugh at me. We then covered a pile of new material (for me), and did it in progressive steps, which was very useful. I learned:

• Breast stroke kick: bring the knees in, kick outward, then sweep legs strongly closed
• Breast stroke arms: sweep out, pulling the head up to breathe, then close in to the chest and straight ahead
• Freestyle*: first swimming on one side, lower arm extended straight above the head and upper one flat down my side, breathing at will; then rolling to switch sides periodically; then just doing a simplified version of the arm stroke and not worrying about breathing (swimming on a single breath); then finally stroking and breathing every fourth stroke (only on the right)

To my surprise, I could do this freestyle thing! The times friends had shown me it before, it was a disaster of uncoordination — too many limbs, plus breathing, to get synchronized. I didn’t do it well tonight, but I did do it a little, and now I think I see how I can practice it on my own. The breast stroke was actually harder to get going with, but I think I see how to work on that one as well. I asked my teacher why the breast stroke used this kind of kick, instead of a simple up/down kick, was it more efficient this way? and that seemed to throw him for a minute. He said, “It’s the kick that goes with the arms for breast stroke.”

After the lesson, I also found some good online resources:

• Freestyle Tips
• Freestyle Instructable: I love the “talk to the fishes, listen to the fishes” bit. The Instructable also includes this interesting tip: “Your legs require 2x as much energy as your arms, but your arms can generate 2x as much propulsion. That’s why distance swimmers basically only kick enough to keep their feet floating.”
• Freestyle instructional videos
• Several sources suggest breathing every third stroke, so that you alternate sides and develop strength equally. I’ll try that next time.

After dance class Sunday, Jazzercise on Monday, dance practice on Tuesday, and now a swim lesson on Wednesday, I’m starting to feel like today’s over-scheduled children I keep reading about. Well, at least I don’t need anyone to drive me around. :)

*Freestyle: This term always cracks me up. I once asked a swimmer friend why the event was called “freestyle” if everyone does the same thing. He said that it originally was a “free” style event, in which you could do whatever you want — but everyone converged on the same stroke as being the best one. Apparently its real name is “front crawl”.

On Saturday, I attended a Proposition 8 evening protest in Los Angeles. Our protest was part of several across the state, coming to more than 20,000 people protesting the passage of this discriminatory amendment to the state Constitution. There were over 12,000 people in the Los Angeles protest alone.

I had never attended a political rally or protest before. It was a wonderful thing, to march along in this sea of people unwilling to permit the loss of the civil right to marry. The vast majority of them were peaceful, passionate, loving, and even positive: they emphasized the value of marriage and what participating in it means to them. Some of the signs were funny (such as the ones noting wryly that chickens command more public support than gays do–a reference to Proposition 2, which requires more humane treatment of chickens and pigs on farms and passed with 63% of the public vote. Some protesters wore beaks and tailfeathers and carried signs expressing a wish that they could be as lucky as the chickens.) and some were heartbreaking (“Married 6/7/08; Segregated 11/4/08” and “How do you ‘protect’ marriage by banning it?”). Some expressed the inevitable anger: “Keep your Jesus to yourself!” and “I didn’t vote against your marriage!”, or sarcasm: “Protect marriage — ban divorce!”.

The LDS church in particular drew a lot of negative attention due to its massive support for the proposition and encouraging its members to donate in support of it. Signs like “Tax the church!” and chants of “Keep your hate in Salt Lake!” were depressing, both for what they indicate about the church’s activities and for the sentiment they indicate in the protesters.

But overall, there were so many, many people involved, such a large and … oddly … almost happy crowd. Not happy with Prop 8, obviously, but happy to be out in public, sharing views and camaraderie (and drumming and dancing and cheering). I was proud to see them all, proud to march with them and join in the chanting:

What do we want?
EQUAL RIGHTS!
When do we want them?
NOW!

Because even if this proposition does not personally target me, damn it, I still believe in equal marriage rights for all.

Many of us have a mental image of Mercury that’s black-and-white, like 1950’s TV. We liken it to the Moon: a pale, devastated landscape pock-marked with staccato craters and blanketed with the finest grey dust imaginable. But this view, it turns out, is somewhat mistaken–probably influenced by the classic view at right, captured by Mariner 10 in 1975. Mariner 10 did take some color images as well, but they are lower resolution, and only about half of the planet was imaged in color, so they get less press.

Enter MESSENGER, the NASA mission that just executed its second close flyby of Mercury, on its way to a 2011 orbital insertion. With its more capable imaging system, MESSENGER has captured close approximations of “true color” for Mercury, although as always this isn’t as simple as snapping a photograph (CCDs just don’t respond to color the way the human eye does!).

Further, false color is often more scientifically useful than the our mineralogically impoverished RGB views. MESSENGER recently released a color movie that pans across the surface of the planet in fascinating detail. Color differences here yield clues to compositional differences. Note also that you can see a definite change in resolution; later in the movie, the crater edges are less crisp and somewhat fuzzy. I assume that this is because it was imaged during a flyby, not in regular orbit; the spacecraft was only 200 km from the surface at closest approach, but then would have been moving rapidly away. The movie has been adjusted to correct for the geometric distortion, but the reduced resolution remains. Check it out!

I recently came across Steve Yegge’s emacs tips. He’s a man after my own heart:

“Using the mouse is almost always the worst possible violation of economy of motion, because you have to pick your hand up and fumble around with it. The mouse is a clumsy instrument, and Emacs gurus consider it a cache miss when they have to resort to using it.”

Cache miss! I love it.

His article is long, detailed, opinionated, and a goldmine of useful emacs nuggets. It will only be interesting to you if you are at least an intermediate emacs user and, say, you agree with the philosophy noted above. Here I include some of my own tips and commentary on his post.

Steve suggests mapping the CapsLock key to be Control, which is sensible in an emacs world, since you use Control orders of magnitude more often than Caps Lock, and ergonomically CapsLock has the more desirable position. But I’ve always been reluctant to do this, because it’s non-standard, and once you’ve adapted to the unusual layout, you render yourself frustrated and mistake-ridden when using anyone else’s keyboard.

Navigation: I already use Ctrl-s (search forward) and Ctrl-r (search backward) liberally to move around in documents (I agree that this is very handy!) and I do use temp buffers for notes — or rather, only one temp buffer. I only use *scratch* for this, because I like being forcibly reminded that there is no auto-save going on and anything I put there won’t be saved unless I explicitly do so (otherwise my compulsively periodic saving goes on as a background processes, in addition to emacs’s autosave, and I generally assume that anything in an emacs buffer has a good dose of permanence). However, I’ve rarely used the regexp search commands, because it was so tedious to type Meta-x-isearch-forward-regexp. Happily, in this article I learned that there are bindings to be had: Ctrl-Alt-s and Ctrl-Alt-r, respectively. (Actually, on my Mac they are Ctrl-Apple-s and Ctrl-Apple-r.) I agree that this is a spectacularly awkward binding to type, but I don’t use it that often (yet) so I’m willing to try it out before remapping it.

The other super-useful navigation bindings that I regularly use (not mentioned in his article) are Ctrl-[ and Ctrl-] to jump to the top and bottom of the file, respectively.

Buffers and windows: I already use most of the buffer and window management commands he listed (splitting, swapping, closing, and listing buffers) but did learn a new one: Ctrl-x + to balance window sizes. Cool!

GUI stuff: I don’t use the menu bar in emacs (sometimes it’s there, sometimes not; I generally ignore it either way). I do, however, like having a scroll bar. I don’t use it much (again, I dislike using the mouse), but it gives a nice visual indication of where I am in a file and how big it is. Yes, the status bar will tell me that I’m 61% through the file, but the visual is much more intuitive, especially because it shows me how much of the file, proportionally, is currently shown in the buffer window. Steve backs off from his initial recommendation to get rid of the scroll bar with an interesting analog/digital argument.

Steve cites “region selection” as a case where the mouse is actually helpful in emacs. I’ll agree, in the case of rectangular region selection (I don’t even know how to do that with the keyboard, much less efficiently), but I do normal region selection all the time with the keyboard. I set the mark (Ctrl-space), move to the end, and then do whatever I needed to do with the region: copy (Meta-w) or cut (Ctrl-w), usually. He seems to view the “move to the end” as the slow bit, but with Ctrl-s (search forward), as noted above, generally this is speedy as well.

Help: I agree that Meta-x-describe-bindings can be a fascinating (and revealing) exploration of the current mode and the powers available to you. I’ve used this in bibtex mode to good effect.

Query-replace: This is one of my favorite bits of emacs power. I love that I can so easily specify text to find and replace, and do it interactively, skipping from instance to instance and individually saying yes or no, or opting to just say yes to all such occurrences (with a !).

Other tidbits I gleaned from this article are

• Meta-b to skip back a whole word. I can’t believe I never knew this one. I imagine then that Meta-f goes forward a whole word. Hey, it does! I also use Ctrl-t regularly to swap two characters (usually when I typed them in the wrong order), and sure enough… Meta-t swaps two words. Whee!
• M-x list-matching-lines: this one blew my mind. It takes in a regexp and shows you every line in the buffer that matches it (like grep -n -e on the command line, but hey, you’re still in emacs, and if you go to one of those entries and hit return, your cursor jumps to that position in the buffer).

Any additional tips are welcome!