5. Physics News from the Web
Items selected from the bulletins of the IOP and the American Institute of Physics
a) The sound of silence - Infrasound
b) Titan in pictures
c) Ships shed light on geomagnetic field
d) New look for "Newton's bucket"
a) The sound of silence
http://physicsweb.org/article/world/19/8/3 From listening in on volcanoes to detecting nuclear explosions, a global network of infrasound detectors is allowing researchers to tune in to our atmosphere, explain Michael Hedlin and Barbara Romanowicz.
b) Titan in pictures
http://physicsweb.org/article/news/10/5/5 Have you ever wondered what it must have looked like to be aboard the Huygens probe as it hurtled towards the surface of Titan -- Saturn's largest moon -- in January last year? All is now revealed with a highly realistic new movie of the dramatic descent, released by the European Space Agency (ESA), NASA and the University of Arizona. The movie shows the probe's plunge through Titan's thick orange-brown atmosphere before landing on a soft, sandy riverbed. The film was put together from data collected by the Descent Imager/Spectral Radiometer (DISR) instrument during the probe's descent, which lasted 147 minutes. There are links to numerous articles on Titan. The video files are large, 126 MB.
c) Ships shed light on geomagnetic field
http://physicsweb.org/article/news/10/5/7 Geophysicists in the UK have used a mathematical model based on old ships' logbooks to show that the observed decline in the strength of the Earth's magnetic field may only be a recent phenomenon -- and not a fixed trend as commonly thought. David Gubbins and colleagues at Leeds University say that our planet's magnetic field was stable until the mid-1800s and has been weakening steadily only since then. The decline is caused by magnetic flux reversals in the Southern Hemisphere and could point to a geomagnetic flip of the Earth's poles sometime this millennium.
d) New look for "Newton's bucket"
http://physicsweb.org/article/news/10/5/8 What happens when you rapidly rotate the bottom plate of an otherwise stationary cylinder filled with water? According to new work by physicists in Denmark, you produce rotating polygons with up to six corners on the water's surface. This new and spectacular type of "instability" could be used to study a wide variety of complex systems in physics, including rotating flows on Earth, hydraulic machinery in industry, vortices and tornadoes.