Monday Science Links

This week's science:

• Mark Liberman at Language Log takes on the claim that Obama uses "I" too much by (gasp!) actually counting: The trouble with this idea, as often with the insights of the punditocracy, is that there's no evidence that it's true. Worse, evidence is easily available to disconfirm it. In yesterday's post ("Fact-checking George F. Will"), I counted, and discovered that in that "speech delivered last week" — the one about the auto bailout — President Obama used forms of the first-person pronoun at a rate of 1.7% (i.e. 42 instances in 2423 words). Compared to Obama's press conference of 2/9/2009 — before the 2/24/2009 date that Prof. Fish identifies as the pronominal turning-point — this is a lower rate, not a higher one: the 2/29/2009 press conference exhibited a rate of 2.6% (205 of 7,775).
  
• A nice piece in Scientific American online on the evolution (and taming) of the domestic cat: Scholars long believed that the ancient Egyptians were the first to keep cats as pets, starting around 3,600 years ago. But genetic and archaeological discoveries made over the past five years have revised this scenario—and have generated fresh insights into both the ancestry of the house cat and how its relationship with humans evolved.


• Stefan at Backreaction tells us that Betelgeuse is shrinking: This is news I can't let go uncommented, after all my recent posts about interferometry: In a recent Astrophysical Journal Letter, a team of astronomers lead by Charles H. Townes, Nobel laureate for his contribution to the development of the laser, report "A Systematic Change with Time in the Size of Betelgeuse". Betelgeuse, or α Orionis, is the bright red star in the shoulder of the constellation Orion. In 1921, Albert Michelson and Francis Pease succeeded in measuring its diameter as about 50 milliarcseconds (mas), using an interferometer mounted onto the main telescope of Mount Wilson observatory. This was the first time the diameter of a star could be measured. 50 milliarcseconds is a tiny angle, corresponding roughly to the apparent size of an object 100 metres big on the Moon. But given the distance to Betelgeuse, this means the star, when put in the place of the Sun, would fill the solar system up to the orbit of Jupiter.


• Erik at Eruptions looks at the possibility that Mt St Helens is becoming a supervolcano:There has been a lot of chatter in my inbox and on the comments here at Eruptions about the study/press release from Graham Hill's research group talking about the potential for a supervolcano forming at Mt. Saint Helens. This study (presented at the AGU Spring Meeting) was based on a magnetotelluric study of the area around (and below) Saint Helens. For those of you unfamiliar with magnetotellurics, it uses instruments that measure the magnetism and electrical conductivity of the earth to infer the composition of the crust. This is possible because different materials in different physical states have different magnetic properties and/or electrical conductivity. So, this study took magnetic field readings near the modern Saint Helens and interpreted it to try to determine the composition and state of the crust below the volcano. The authors of the paper write that the patterns of electrical conductivity under Saint Helens suggest a large volume of melt underneath the volcano, thus it has the potential to form a supervolcano. And that is where things might have gotten a little carried away.


• Phil at Bad Astronomy looks at Daphnis and what it does to Saturn's rings: The first thing you should know is that Saturn’s rings are incredibly flat. If you scaled them down to the size of a piece of paper, they’d actually be far thinner than a single sheet of that paper. In fact, even though they’re about 200,000 kilometers across, they are only at most a few dozen meters thick! But not everywhere. Daphnis is a teeny tiny moon, just 8 km (5 miles) across. It orbits Saturn inside the broad A ring, and it’s carved a gap in the rings called the Keeler Gap. The gap is about 45 km (25 miles) across. As it happens, Daphnis has an orbit that is not perfectly circular, so sometimes it’s in the middle of the gap, and sometimes near the inner edge. Not only that, but the orbit of the little moon is tipped a bit, so sometimes it’s a bit above the ring plane, sometimes a bit below. When it’s near the inner edge and also above the ring plane, it pulls the nearby ring particles up out of the ring plane with it. When it’s below the plane it pulls the particles down. When the elliptical motion of the moon is combined with the tilt, the gravitational interaction on the ring particles produces vertical ripples in the ring. These ripples have been predicted in the past, but now Cassini has clearly imaged them for the first time.

Enjoy!