Archive for September, 2006

Data Fit Model for B Ring

Monday, September 11th, 2006

A couple of weeks ago I posted this prediction based on our self-gravity wake model for Saturn’s B ring. Basically, depending on the angle that we look at Saturn’s rings, we see a different amount of starlight shining through. That amount depends on the size, shape, spacing, and orientation of clumps of particles in the rings that, in the case of the B ring, are about as wide as a football field, and perhaps much longer. Using our first set of measurements we calculated the size, shape, spacing, and orientation of the B ring clumps, and I used that to predict our next B ring measurement. Well, now we have that measurement, and I’m happy to report the agreement is pretty good. In the images below, the red diamonds are the predicted values and the blue curve is the measurement. The green curve is an earlier measurement that gives an indication of the range of values between different measurements. These results are preliminary, but the agreement here, like that for the A ring, shows that the self-gravity wake model is working well to explain our measurements of the rings. We still need to understand all the structure in the rings responsible for the bumps and wiggles in the blue and green curves. And future measurements will certainly allow us to improve this initial self-gravity wake model.

Comparison of model prediction and observation for inner B ring

Comparison of model prediction and observation for middle B ring

Comparison of model prediction and observation for outer B ring

Solar Energy Requirements of the U.S.

Sunday, September 10th, 2006

The Department of Energy estimates 4,038 billion kiloWatt-hours of electricity were expended in the United States in 2005. The flux of the Sun at the top of the Earth’s atmosphere is about 1 kiloWatt per square meter. From these two numbers it is easy to estimate how much area in solar panels would be needed to provide the current electrical needs of the entire country.

There are 8766 hours in an average year, so the average electricity consumption in 2005 was 460 million kiloWatts (4,038 kW-hours/8766 hours). For the United States we only have sunlight available for about half the time (12 hours out of 24), and it does not shine directly on the ground due to our moderate latitude. So let’s knock that kiloWatt per square meter of sunlight in half for the nighttime, and in half again for the oblique angle of the sunlight, and we get 250 Watts per square meter. With 10 per cent efficiency of solar panels we would get 25 Watts (0.025 kW) per square meter of photovoltaic cells. That means it would take 18 billion square meters (460 million kW/0.025 kW) of photovoltaic cells to supply all of the country’s current electrical usage. 18 billion square meters is a big number, but the United States is also big. If we put that in one large solar panel farm it would have to be 134 km by 134 km, or about 80 miles on a side. This is a remarkable number. It means that with current technology we could get all our electrical power needs with relatively small chunks of real estate.

Imitative Monkeys

Sunday, September 10th, 2006

Check out some of the cool blogs in my links. For example, the skepchick has this cool report on an interesting story about the imitative behavior of monkeys.

Iraq and al Qaeda: U.S. Linked Them

Saturday, September 9th, 2006

The Senate, and even Mr. Bush, have now clearly stated that there was no connection between Iraq and al Qaeda before September 11 and, in fact, before we invaded. Now al Qaeda has quite a presence in Iraq. Gee, who’d a thunk it.

Crank

Friday, September 8th, 2006

This dark comedy is as pumped full of adrenaline as its protagonist, Chev Chelios (Jason Statham), a hit man who spends the movie trying to fight off the effects of a slow-acting poison while he seeks vengeance on those who killed him. Why didn’t Verona just shoot Chev when he had the chance? Because Verona, like many people in the movie, is sadistic and wanted to rub Chev’s face in the fact that Verona had killed him. Unfortunately for Verona, the poison is temporarily offset by large amounts of adrenaline. So Chev embarks on a frenetic chase to get Verona, get some epinephrine (recommended by his shady doctor, played perfectly by Dwight Yoakam), and protect his girlfriend Eve (Amy Smart) from Verona’s inevitable attack.

The movie is presented in the way that Chev is experiencing his last hours of life: frenetic, confusing, sometimes blurred, and with images from his life popping up in odd places. The editing is fast and furious. Although not quite an hour and a half long, the frantic action-packed pace of the movie makes it exhausting. I liked it, but was glad it wasn’t longer. This is a dark comedy of sorts, although I suspect the laughter is born of nervous excitement and is a release of tension that the movie generates in abundance. In between severing one thug’s hand and a major gun fight with lots of blood and corpses, Chev races across Los Angeles in a hospital gown so souped-up on epinephrine that he couldn’t slow down if he wanted to. The violence is abundant and bloody, so this movie is not for everyone, but it is a beautifully executed wild ride.

SMART-1 Hits the Moon

Wednesday, September 6th, 2006

Cool pictures taken by SMART-1 from its last few orbits, along with before and after pictures of the impact site, can be found here at the Planetary Society blog.

The Illusionist

Wednesday, September 6th, 2006

I went to this movie with some trepidation because previews and reviews gave the impression that Edward Norton’s character, Eisenheim the Illusionist, possesses supernatural powers. I generally find movies (and TV shows) that promote the idea that people have psychic or other supernatural powers to be offensive and detrimental to our cultural literacy. However, leaving aside whether or not Eisenheim actually does have supernatural powers, I liked this movie and the character and was willing to go along with him being able to pull off real magic, basically because it was an interesting story and because it was not set in the present day. Set in turn-of-the-century (2oth, that is) Vienna, Eisenheim puts on a show that is far beyond cheap tricks and sleight of hand. When the Duchess Sophie von Teschen (Jessica Biel), fiancee of the smart but sinister Crown Prince Leopold (Rufus Sewell), is volunteered by said Prince to participate in Eisenheim’s act, he recognizes her as his teenage sweetheart from 15 years ago.

Leopold has his sights set on Sophie for his own political aspirations, and in any event Eisenheim is not of the aristocracy so their love story seems doomed. The meat of the movie is a battle of wits between Eisenheim and Leopold, with Police Inspector Uhl (Paul Giamatti) working for Leopold but primarily interested in the truth of the affairs between them. He’d also like to know how Eisenheim does his considerably cool tricks. As for whether they are tricks or magic, that is best left to the movie. There is plenty of romantic atmosphere, a fun detective story, and another winning performance by Norton.

The Crocodile Hunter

Wednesday, September 6th, 2006

The sudden and dramatic death of Australian zoologist and animal enthusiast Steve Irwin, affectionately known as the Crocodile Hunter, hit me surprisingly hard. His show on Animal Planet was both educational and entertaining, and his over-the-top boyish enthusiasm was contagious. While we frequently marveled at the apparently perilous situations he put himself in, I always felt that this was someone who was fully aware of the nature of the animals around and was not taking inordinate risks. His death is sad and depressing. The Crocodile Hunter was a larger-than-life personality who was also immensely likable. His frequent adventures with dangerous animals gave him an air of invincibility, and he appeared to be someone who just truly loved every aspect of life. His death in a relatively freak accident destroyed the real-life superhero illusion that he created on his show and drives home once again how fragile life is. His goofy charm always made me smile, and I will miss him.

Trust the Man

Monday, September 4th, 2006

This movie superficially has all the makings of an engaging, intelligent, romantic comedy, but it never gets much beyond a promising setup and a smattering of quirky scenes. Two troubled couples struggle with their partners and with their friendships with each other in Manhattan, while a parade of notable actors in eccentric secondary roles adds depth to the background. The cast is led by Maggie Gyllenhaal as Elaine, who is ready to start a family, and Billy Crudup as her boyfriend Toby, who spends his time making the sort of snide irrelevant commentary that you’re likely to find on this blog. Toby’s sister, Rebecca, is played by Julianne Moore whose marriage to Tom (David Duchovny) is going through mid-life doldrums.

While there are some amusing scenes, too much seems like a set-up instead of a natural flow of events. In one scene, a foreigner of unknown origin whom Elaine dates speaks with such a ridiculous accent and says such ridiculous things that the movie seems to have left the real world for a detour into farce. Toby has two bizarre, interrupted sessions with a therapist (played by Bob Balaban); a publisher played by Ellen Barkin makes a bizarre pass at Elaine; Tom and Rebecca have their own bizarre therapy session to start the movie. These scenes and others, apparently designed for comic effect, prevent the main foursome from being developed as real characters as much as they could have been if they weren’t regularly being interrupted by the absurd. The cast gives it their all, and the movie has its moments, but by trying to do too much it somehow manages not enough.

Crashing on the Moon

Saturday, September 2nd, 2006

The European Space Agency’s SMART-1 experimental spacecraft will have a planned (meaning expected) crash landing on the surface of the Moon sometime this weekend. A couple of years ago, of course, we had the planned (really meaning planned, as that was the whole point of the mission) impact of part of the Deep Impact spacecraft into the nucleus of a comet so that the resulting debris from the interior could be studied. While the SMART-1 impact is not part of a planned scientific experiment, it will provide another useful data point on the study of cratering in the solar system. Craters abound on planets, moons, asteroids, and comets. They provide a nice historical record of the abuse that those objects have suffered over the ages. By untangling the pattern of craters on the surface of an object such as the Moon, we can learn what the history of debris in the solar system has been. For example, the Moon’s craters appear to show that there was a great cataclysm of impacts some 700 billion years after the formation of the planets was mostly complete. While the SMART-1 impact won’t shed any light on the mystery of this so-called Late Heavy Bombardment, it will help us understand how big a crater is produced in a particular impact. Usually we have to use computer models to estimate the size and speed of an object that produced any particular crater. In this case, we will know the mass and speed of the impacting object at high precision, and future lunar orbiters, in particular the Lunar Reconaissance Orbiter scheduled for launch in 2008, will be able to see the crater that it produces.