Monday Science Links

This week's sciency goodness:

• Michael at Paleoblog posts on the asteroid that killed the dinosaurs: Responding to challenges to the hypothesis that an asteroid impact caused a mass extinction on Earth 65 million years, a panel of 41 scientists re-analyzed data and provided new evidence, concluding that an impact in Mexico was indeed the cause of the mass extinction. Thirty years ago, Luis Alvarez, Jan Smit and their coworkers suggested a large meteorite slammed into Earth 65 million years ago and caused one of the most severe mass extinctions in Earth's history, ending the age of the dinosaurs. In 1991, a more than 200-kilometer-wide impact crater was discovered in Yucatan, Mexico, that coincided with the extinctions. Since then, the impact hypothesis has gained overwhelming acceptance within the scientific community.
  


• At Skulls in the Stars, a post on an optical illusion: One of the wonderful things about having a career in science is that a deeper understanding of the science leads to a greater appreciation of its beauty. In physics, this usually requires a nontrivial amount of mathematics, but there are some phenomena that are self-evidently beautiful; unfortunately, many of these are also not very well known! In working on my textbook on optics, I delved rather deeply into one of these phenomena, known as the optical Talbot effect. First observed in 1836 by Henry Fox Talbot, the effect went unnoticed for nearly fifty years before being rediscovered by the great Lord Rayleigh in 1881. The true subtlety of the phenomenon was still not understood, however, for another hundred years!
  


• Jessica at Magma Cum Laude posts on her recent fieldwork (with photos!): I suppose I've left you all hanging long enough, so now it's time to show off the first batch of photos from Guatemala. The trip started out in Guatemala City, where we loaded up our rental car and drove to Quetzaltenango (known as Xela or Xelaju to most people). From Xela we drove to a finca, or farm/plantation, and then spent three hours hiking through jungle, over landslide scars and down rocky riverbeds. It was a tough, messy hike, although we were lucky enough to have porters go first and cut a path through the brush with machetes. (This did have its drawbacks, though, since the average Guatemalan is shorter than me, and we had some pretty tall people in the group. There was a lot of stooping and some crawling, which isn't all that fun when the foliage is covered in volcanic ash.)
  


• Erik at Eruptions posts on a possible Icelandic eruption: We talked a few weeks ago of signs that there were increasing signs that an eruption could occur on Iceland - increased seismicity on the Reykjanes Ridge suggested that magma might be on the move. Now, we have two pieces of evidence that we might see activity at Eyjafjallajökull, on the southern side of the island nation.
  


• Ed at Not Exactly Rocket Science posts on dinosaur-eating snakes: Snakes have been around for nearly 100 million years and scientists have found many fossils of extinct species. But this astonishing specimen is different. This serpent is Sanajeh indicus. It is sitting in a dinosaur nest and its coils surround three eggs and the body of a hatchling. There are many reasons to think that this prehistoric tableau represented a predator caught in the act of hunting, rather than a mash-up of unconnected players thrown together by chance. The snake is perfectly posed, with its head resting atop a coil and its body encircling a crushed egg. All the pieces are very well preserved and very little of the snake, the dinosaur or the crushed egg have been deformed. All of this suggests that the animals were caught unawares and quickly buried in sediment.
  

Enjoy!